Odo
Odo was a Changeling who served as chief of security aboard the space station Terok Nor, later known as Deep Space 9. He was the only known Changeling to reject the Founders’ beliefs and instead gained an appreciation for humanoid species. Despite being affiliated with several groups in that capacity, the Bajoran Militia, Cardassian Union, , and Dominion, he gained a widespread and respected reputation from all these groups for being a fair enforcer of the rule of law. (, , , )

Origins 
Odo was one of the "Hundred Changelings", a group of one hundred newly-formed Changelings that the Founders sent out into the galaxy, "centuries ago", to gather information and explore, and was not expected to return until the late 27th century. ()

In the 24th century, Odo was found adrift in his natural gelatinous state in the Denorios belt in the Bajoran system and was brought to the Bajoran Institute of Science where he would be studied by Doctor Mora Pol for seven years. Not initially recognizing Odo as a sentient being, Mora subjected him to a long series of experiments, in which Odo endured time in a vacuum chamber and a protein decompiler, as well as extensive electric shocks. Odo eventually rebelled against Mora's unintentional mistreatment by forming into a tentacle and hitting him, () before later forcing Mora to recognize him as sentient by copying a beaker on a laboratory table. ()

Odo's name stemmed from the Cardassian word for "nothing", Odo'ital, which was the loose translation of the "unknown sample" label in Bajoran on his laboratory flask. After he was discovered to be sentient, the scientists began jokingly referring to him as "Odo Ital", in a similar manner to a Bajoran name, which eventually got shorted into simply "Odo". () He himself used only the single name "Odo". () Early in his life, when he heard others address him as "Odo", he heard it as "nothing". He felt that the name was appropriate, since he had no friends, no past, and no form; once he had gained the respect and affection of Kira and the others on the station, he ceased hearing "Odo" as "nothing" and simply considered it his name. ()

Later in life, Odo recalled that when he was first discovered, "I didn't know what I was. I had no memory of where I was from. I didn't even know I had the ability to mimic other forms." ()

Mora continued to study and teach Odo during the Occupation of Bajor, assisted by Dr. Weld Ram. When Odo assumed humanoid form, he copied Dr. Mora's hairstyle. During the Occupation, Odo performed a Cardassian neck trick that greatly amused the Cardassian officers. When Odo left Dr. Mora's institute, he did not leave on good terms; he resented some of the methods Mora had used on him and blamed him for not realizing that he was sentient. ()

Odo later recalled, in 2370, that when he was younger, "people were always asking me to change shape for them. They'd pretend to be my friends, but all they wanted was to see me become a chair or an animal. None of them ever really cared about me." ()

Cardassian occupation 

At some point during the Occupation, Odo arrived on Terok Nor. He was seen as an impartial outside observer and often settled disputes between the Bajoran workers on the station. In 2365, due to his reputed neutral position, Odo was recruited by Gul Dukat to investigate the murder of a Bajoran collaborator. Among his chief suspects was Kira Nerys, who Odo found out to be a Bajoran resistance fighter. He lied about this to Dukat and did not reveal her identity but, in 2370, discovered that Kira was indeed the murderer. In their initial encounter, Kira sardonically called Odo "Constable", a term she later adopted as a term of affection, and which eventually fell into common use as an unofficial title for him. ()

Odo continued working for the Cardassians, eventually becoming chief of security.

In 2366, Odo investigated an assassination attempt (a bombing) on Dukat. Three Bajoran workers were initially linked to the attack, and Odo – too concerned with maintaining order and the rule of law – hurriedly convicted them and allowed them to be executed. If he had performed any kind of investigation instead of relying on circumstantial evidence, he would have seen that the three men were clearly innocent. However, he didn't know the difference between "order" and "justice" at that time.

A bombing identical to the one that nearly killed Dukat occurred three days later, and Odo realized the men had been innocent and that his lax investigative procedures had caused a serious miscarriage of justice. This incident prompted him to be much more insistent on actual justice, though not necessarily the actual letter of the law. Odo's guilt was revealed when, after traveling through a plasma storm, his mind formed a link with the other passengers – Captain Benjamin Sisko, Elim Garak, and Lieutenant Commander Jadzia Dax – and caused them to relive what had happened seven years prior, the three men taking on the roles of the convicted men while Dax represented an unidentified Bajoran woman in an hallucination of the past. ()

Later in 2366, Odo was designated an officer of the Cardassian court in order to testify in criminal cases. ()

It was quite clear that his Cardassian employers still viewed him with suspicion; an automated counter-insurgency program designed to activate in the event of a slave revolt on the station was programmed to raise a force field around Odo's office on the assumption that he would shift sides to aid the insurgents. ()

As an investigator in a totalitarian regime, Odo was occasionally required to operate outside official channels, and he maintained a clandestine network of debts and allegiances to high-ranking members of the Cardassian government, which he could call on when needed. In the course of his career, he developed an extensive knowledge of espionage and assassination techniques, such as poison, explosives, and scrambling signals. ()

Deep Space 9

Chief of security 

Odo retained his post as chief of security even after the Cardassian forces withdrew from the space station in 2369, when the station fell under Federation administration and was renamed Deep Space 9. Odo never held any rank but was informally referred to by the title constable, which was first used by Kira upon their first meeting in 2365. () He sometimes gave orders to officers who had a formal rank but were part of his staff, indicating that his role as chief of the security staff took priority over the rank structure in certain instances. ()

At first, Odo and Starfleet Commander Benjamin Sisko, the station's then-new commanding officer did not see eye-to-eye on how station security should be handled, but they eventually became close associates. () Sisko stood by him when he was accused of killing a Bajoran he had arrested years earlier. When the Bajorans on the station became unruly and wanted to harm Odo, Sisko protected him. The situation was resolved when it was discovered that the Bajoran, Ibudan, had faked his own death in order to take revenge on Odo. ()

Having been found in the Denorios belt, the discovery of the Bajoran wormhole provided Odo with further opportunity to investigate his origins. He was tricked by Croden into believing he had discovered Odo's people. The story had been fabricated by Croden to manipulate Odo into helping Croden rescue Croden's daughter. Croden apologized to Odo for the deception and wished him luck in finding his people. ()

Odo resolved a conflict between Kira, who threatened mutiny, and Sisko, who wanted to arrest her for treason. Both were being mentally affected by Saltah'na energy spheres that contained a log of a similar battle in an ancient culture, causing the crew to do the same thing. Fortunately, Odo's non-organic nature rendered him immune to the effects of the spheres, and with the aid of Doctor Bashir, he was able to remove the spheres' influence and eject them out of a cargo bay door. ()

As the outcome of an investigation regarding a Cardassian claiming to be war criminal Gul Darhe'el, Odo managed to prove that the man was actually Aamin Marritza, a file clerk for Darhe'el who wanted the Cardassian people to realize their crimes. ()

In 2370, an extremist group of Bajorans known as the Circle, led by Minister Jaro Essa and supported by Vedek Winn Adami, demanded that all non-Bajorans leave DS9 and Bajor. Civil war threatened the planet, but Quark informed Odo that the Circle was being helped and financed by Cardassia in order to drive out the Federation, leaving the planet ripe for reconquest. Weapons had been smuggled to the Circle through Kressari traders, which Odo revealed by using his shapeshifting abilities to "borrow" a passenger manifest with a Gul's thumbscan on it. ()

When Odo was affected by a gas in the Gamma Quadrant that turned him into a destructive creature, Dr. Mora, the scientist who had discovered him, helped cure him. ()

Together with Lieutenant Jadzia Dax, Odo, while in the Gamma Quadrant, discovered a planet where people were disappearing. The people were actually holograms created by Rurigan, the sole survivor of a planet destroyed by the Jem'Hadar. Odo and Dax fixed the holographic projector and restored the people. In the process, Odo formed an attachment to a girl called Taya, even shifting into a spinning top for her amusement before he and Dax departed. ()

Odo helped represent Miles O'Brien in a Cardassian court on false charges of aiding the Maquis. Odo's knowledge of Cardassian law annoyed the court, and his delaying tactics provided time for Sisko to prove the evidence false and gain O'Brien's release. ()

During a mission to locate the Founders of the Dominion in the Gamma Quadrant, Odo found himself drawn to  in the Omarion Nebula. There, he discovered that the Founders were in fact Changelings like himself. After initially becoming annoyed with shifting into every plant and rock he could see, with the aid of the Female Changeling, he changed into a bird and took flight, finding that he enjoyed exploring his shape-shifting abilities. He soon discovered the Founders' distrust of "solids", though, and rejected them in favor of his friends, with the Female Changeling acknowledging his request for the time even if she warned him that he wouldn't be as fortunate in future interaction. ()

Later that year, Odo had another encounter with the Founders while he was on an away mission with Kira. They landed on a planet to answer a distress call that seemed to come from a Maquis raider in the area. While on the planet, Kira was captured, and the Female Changeling assumed the appearance of Kira. The Changeling pretended that she was trapped inside a growing crystal that was suffocating her. After Odo admitted having romantic feelings for Kira, he was able to see through the ruse when she claimed to feel the same way; he was sure that Kira didn't love him but knew she wouldn't lie to him about something so important. It gave the Changeling an understanding of Odo's feelings for Kira, although Odo still refused to admit how he felt to the real Kira, simply claiming to have seen through the deception due to a 'slip of the tongue' that the real Kira would never have said. ()

In 2371, a newly-"born" Jem'Hadar was found among the wreckage of a salvaged ship Quark had purchased. The baby matured into an adolescent within days, and as a Changeling (and therefore a Founder in the boy's eyes), Odo inherited the responsibility of looking after him. The Jem'Hadar was willing to do literally anything Odo asked of him. Odo tried to break the boy of this habit and encouraged him to think for himself and resist his inborn tendency toward violence. Ultimately, the boy decided that he belonged with the other Jem'Hadar and that anyone who was not Jem'Hadar was his enemy, arguing that if Odo actually accepted his right to self-determination, he would respect his wishes. Odo, wanting to protect the crew, escorted the boy to Dominion space. ()

It was also during this time that Odo had requested his own personal quarters, and was decorating them with furnishings appropriate for himself, allowing him to experiment with his abilities in private. ()

Also in 2371, Odo was forced to admit to Elim Garak that, despite his disgust at the Founders' behavior, he still wanted to return home. He accompanied Garak in an attempt to contact Enabran Tain. Odo became a prisoner of Tain, who was plotting, along with the Romulans, the extermination of the Founders. The plot failed, and Odo was aided in his escape by a Founder who was posing as a Romulan on Tain's ship, although he still rejected the offer to return home. This resulted in the Battle of the Omarion Nebula, in which both the Romulan Tal Shiar and Cardassian Obsidian Order were decimated. ()

Odo also served as host for Curzon Dax during Jadzia Dax's Trill zhian'tara, during which Odo shifted into a form resembling Curzon. Initially, the two wanted to stay together, but Curzon was eventually convinced to return to the  symbiont. This gave Jadzia a greater understanding of the joy Odo found in his shape-shifting abilities, and Odo learned how much fun solids had staying up all night drinking and playing tongo. ()

In late 2371, Odo was forced to kill  posing as Ambassador Krajensky, who had tried to provoke a war between the Federation and the Tzenkethi. By killing the impostor, Odo became the first Changeling ever to harm another. ()

Odo – along with Rom, Quark, and Nog, – time traveled to Earth of 1947. None of the Ferengi were aware of Odo's presence until he revealed himself as having shapeshifted into the guise of a German Shepherd dog, Odo having sneaked onto a shuttle the Ferengi had traveled there in, Quark's Treasure, in order to catch Quark in flagrante delicto, smuggling. This became known in Human history as the Roswell Incident. Along with the three Ferengi, Odo eventually managed to escape back to the 24th century and Deep Space 9. ()

In 2372, Odo accompanied Sisko, who now held the rank of captain, on a trip to Earth to advise Starfleet Command on the Changeling threat. Odo was able to demonstrate to the organization how easy it would be to infiltrate Starfleet, and subsequently helped free Sisko from a prison after Admiral Leyton, a former mentor to Sisko, was revealed to be staging a military coup. () While visiting Earth on this occasion, Odo was secretly infected with a morphogenic virus by rogue organization Section 31, in the belief that he would eventually link with others of his kind, transferring the disease and ultimately eliminating his entire species. ()

Odo protected Shakaar Edon, the head of the Bajoran government, while Shakaar visited the station, even though Odo was jealous of him because Shakaar was in a relationship with Kira. ()

When Worf's brother, Kurn, arrived on the station after being dishonored by the Klingon High Council due to Worf siding with the Federation in a Klingon attempt to conquer Cardassia, Odo gave Kurn a job of security officer, although this ended when Kurn made near-constant attempts to commit suicide. ()

Odo also went on a joint mission with the Jem'Hadar to stop a group of renegade Jem'Hadar from capturing an Iconian gateway. ()

Later that year, Odo became desperately ill, not as a result of the virus, but because he had been poisoned by his own people in order to force him to return to them for treatment. Once there, he was judged by the Great Link and forced into his humanoid form permanently, unable to change shape, as punishment for harming another Changeling. While Odo was locked into a humanoid form, it hinted that he was essentially still a Changeling because, as Dr. Bashir later pointed out, Odo's brain still contained morphogenic components. The other shapeshifters may have just used their greater collective ability while linked with Odo to force him to alter his form into that of a humanoid, guiding the specific elements of his transformation such as Human physical makeup based on their expert knowledge of Humans. While part of the Link, Odo unwittingly infected his entire race with Section 31's bioweapon. Also, owing to information Odo had gleaned in the Link, he was convinced that Chancellor Gowron, the leader of the Klingon Empire, was actually a Founder. ()

Life as a solid 

Permanently locked into his solid state, Odo became extremely depressed. He found some comfort in the new sensations of eating and drinking, but this gave him little solace. Odo's frustration was exacerbated when Captain Sisko decided to bring him on an undercover mission to expose Gowron as being a Changeling infiltrator. If Odo had still been a Changeling, he could have simply changed into Gowron's pet targ. Instead, he, Sisko, O'Brien, and Worf disguised themselves as recipients for the Order of the Bat'leth and attempted to use polaron radiation to expose Gowron as a Changeling.

Odo, using the alias "Kodrak", proved to be a less than intimidating Klingon, but the mission went as planned until someone recognized their true faces. The Starfleet officers were exposed and nearly executed, but General Martok helped them escape to complete their mission in the name of the Empire. Although Worf almost killed Gowron in honorable combat, Odo had deduced, by this time, that "Martok" was the true Changeling and Odo's information about the infiltrator had been deliberately falsified by the Founders to provoke further unrest between the Federation and the Klingons, weakening them and paving the way for a Dominion invasion of the Alpha Quadrant. The mission was ultimately a success and the Martok Changeling, having been identified by Odo, was killed by a barrage of disruptor fire. Before undoing Odo's Klingon alterations, Bashir mentioned that he could surgically alter Odo's face to realistically resemble any humanoid; Odo declined the offer as he preferred his face the way it was. ()

It was during Odo's time as a solid that the , through the treachery of an undercover Klingon named Arne Darvin, was sent back in time to the year 2268. The ship found itself near space station K-7 at a crucial moment when Darvin had been exposed as a spy and subsequently disowned by his people. Odo helped search for an explosive tribble to prevent Darvin from killing James T. Kirk, and even acquired one as a pet. He found Worf's recounting of the Klingons' "war" against the tribbles rather amusing, finding it hard to believe that a cute ball of fur was a "mortal enemy" of the Klingon Empire. ()

Apparently, the Founders' attempt to force Odo to remain a solid took some time, as a plasma storm later reacted with leftover morphogenic enzymes and therefore caused his mind to telepathically reach out to link with other Changelings. At the time, he was returning from a conference with Sisko, Garak, and Dax, when the four of them were suddenly trapped in a dream-like but utterly realistic recreation of the Cardassian Occupation based on Odo's memories. The people in the dream believed them to be a group of Bajoran terrorists who had been executed during the Occupation, but instead of Odo, his predecessor Thrax was in charge. Odo did not realize (or did not want to admit to himself) that Thrax's actions in the dream were in fact a recreation of his own, and their personae there were a group of innocent Bajorans who had been executed because Odo had sided with order rather than his sense of right and wrong. The experience, a product of Odo's guilt, persuaded him to admit the truth to himself and others. ()

In 2373, Quark found an infant Changeling among some salvage he had purchased and sold the infant to Odo. He, in collaboration with Dr. Mora, made attempts to teach the infant, which was very ill, to change form, just as Mora had done with Odo himself. Though their attempts did result in making the infant form a face to look at Odo (along with various other shapes, assuming them seemingly at a much faster rate than Odo had when in Mora's care), its morphogenic matrix began to destabilize. As it died in Odo's hands, it linked with Odo and restored his morphogenic matrix, allowing him to change form once again. This was done as a means of thanking its mentor for all that he had tried to do. As Dr. Mora departed the station, he encouraged Odo to think of his restored abilities as a gift the Changeling had wanted him to have, and Odo, in return, told Mora that he now had a better understanding of what Mora had done for him years ago. ()

The Dominion War 
After the Dominion captured Deep Space 9, Odo was one of a few crewmembers who remained on the station, retaining his old role as chief of security, only with Dukat in charge. Odo joined the Ruling Council at the invitation of Weyoun. After the Female Changeling arrived on the station, his loyalties were questioned. The Female Changeling realized that the reason Odo remained with the solids was his love for Kira. She linked with Odo, hoping to manipulate him. While Kira led a resistance cell, Odo did nothing to help. Rom was arrested, but Odo again did nothing, stating that he was at peace after his linking. His inaction directly led to thousands of deaths as Starfleet was forced to accelerate their plans to retake DS9, going without an entire fleet to meet an enemy who outnumbered them two to one. Kira was later put into the brig and when the Female Changeling explained her plans for the solids, including the execution of Kira, Odo's eyes were opened. During a subsequent battle to retake Deep Space 9, he helped Kira and Rom escape from custody. Odo and his security forces attacked the station's guards, allowing Kira and Rom to disable the station's weapons system, helping the Defiant to retake the station. ()

In 2375, Odo tried to help Weyoun 6 defect to the Federation, as Weyoun 6 believed that the Dominion War was a mistake, but his programming meant that he still saw the Founders as gods; contacting Odo was as close to a compromise as he could come. Due to an attack perpetrated by Weyoun 7 and four Jem'Hadar ships, the attempt failed and ended with Weyoun 6's death; he triggered a termination implant in his brain that killed him in a matter of minutes. At this time, Weyoun also revealed that the Founders were all dying of a strange disease, and Odo was the only one who seemed unaffected by the disease. ()

Some time after this, it was revealed that Odo was the original source of the morphogenic virus that was killing the Founders, having been infected by Section 31 during his brief visit to Earth, () in an attempt by Section 31 to end the threat of the Founders by committing genocide. Odo was beginning to die of the disease himself, but after tricking Section 31 agent Luther Sloan into coming to DS9, Bashir was able to discover a cure for the virus, although it necessitated him and O'Brien each using a neural interface to enter Sloan's dying mind when the agent tried to kill himself rather than reveal the cure. ()

Odo was instrumental in ending the war with the Dominion. He and Colonel Kira joined a Cardassian resistance group led by Damar. As such, Odo provided valuable help in Damar's fight against the Dominion. When the Female Changeling refused to order Jem'Hadar and Breen forces to stand down, Odo linked with her, curing her of the virus and convincing her that she was wrong about solids and to stand trial after ending the war. In exchange, Odo agreed to return to the Great Link permanently to help build a new Dominion, and to cure his people. This meant the end of his relationship with Kira, though he was accompanied on his return to the Great Link by Kira. As he merged into the Link, he changed into a tuxedo, which Kira liked him in. ()

Beliefs 
Odo had a deep sense of justice, which he valued above all other things. As he told Sisko at one point, "Laws change depending on who's making them, but justice is justice." () Because of this, Odo enjoyed "thumbing his nose" at authority and going by his rules rather than those of Starfleet. () He once speculated that his belief in justice was an innate part of his racial makeup, and thus a link to his lost people. () When his people revealed themselves to be the Founders of the Dominion, they claimed that what they desired was order, not justice. () A desire for order was present in Odo's personality also, however, and it was expressed in his sometimes-authoritarian methods, which were justified because, in his view, they made things safer. As part of his jobs, he would, for example, spy on people's private communications and he wanted to introduce a general curfew to the station, be allowed to search more arriving passengers, and wanted dozens of extra security staff. His views on order sometimes made him blind to the plight of those who might be oppressed. In his view, the space station was safer under Cardassian control because of the powers given to security staff - an opinion his friend Kira Nerys corrected by pointing out it was not safe for Bajorans at that time. Odo admired the efficiency of the ruthless Cardassian intelligence agency the Obsidian Order. ()

Odo's service during the Occupation changed his attitudes about justice significantly. When he began working for Gul Dukat, he believed he was on neither the Bajoran nor Cardassian side, an impartial investigator whose only goal was to find the truth. Experience during the Occupation and being forced to choose sides when the truth would not lead to justice caused him to realize that contrary to a Human axiom, justice is not blind. During this time, he also began to distinguish justice from order, recognizing that he preferred the former after he allowed three Bajorans to be unjustly executed. When DS9 was under Federation command, Odo released Cardassian political prisoners from his jail whom the Bajorans wanted handing over to the Cardassians in exchange for the release of Bajoran prisoners. He did so because he thought it unjust that that they should be handed over. ()

As late as 2369, Odo had never "coupled", claiming he chose not to do so. He saw too many compromises involved in humanoid relationships and failed to understand the humanoid obsession with coupling. () Odo also believed in punctuality. His daily patrols of the Promenade were so routine that shopkeepers could set their watch to him. ()

Shapeshifting nature and ability 
Odo did not have the benefit of connection with the Great Link while he matured, and as a result, he was relatively unskilled in the use of his shapeshifting abilities when compared to most other Changelings. Unlike Odo, other Changelings, such as the Female Changeling, showed little difficulty in mimicking the faces of Kira Nerys and others. ()

Nonetheless, Odo was able to improve his abilities with time and practice. By shapeshifting into an object, not only was he able to create a visual representation of the object; he was able to duplicate the object to such degree that if he was scanned with a tricorder while he was in the shape of a bird, the tricorder would detect a bird. ()

Odo did not have a sense of smell, or a sense of taste either, which is part of the reason he disliked eating; he noted once that he had actually attempted to eat shortly after he first mastered the ability to assume a humanoid form but commented that the lack of a digestive system had made the whole process very messy, without elaborating further. () When the situation was appropriate, Odo was able to use his shapeshifting ability to create a visage of a table setting with a meal which he could "consume," and in doing so be a part of the dining experience. ()

Odo did not wear real clothes, instead creating his uniform from his body. Despite his difficulties imitating certain humanoid features, he was skilled enough as a shapeshifter to imitate some technological devices well enough for them to be functional, including his combadge on his uniform. But on at least one occasion Odo elected to wear a "real" combadge. ()

Odo could not hold a form permanently, and had to regenerate on a regular basis, generally every sixteen hours. During this time, he returned to his natural state for a period of several hours. Nevertheless, in 2369, while trapped in a turbolift for several hours, Odo showed signs of distress when approaching the fifteenth hour mark since the time of his last regeneration; physical changes in his appearance were already beginning to show. () Several years later, while bunk mates with Quark during a mission on the Defiant, Odo appeared fine physically, even if highly agitated, when – interrupting multiple attempts Quark made to engage in conversation – Odo explained he had been holding his shape for a full sixteen hours. () In one case, Garak tortured Odo by preventing him from regenerating, using an Obsidian Order device that prevented Changelings from changing form. The inability to regenerate appeared to cause Odo great distress and pain, as well as causing his physical appearance to begin to fall apart. () Other Changelings did not seem to have this difficulty; when suffering from the Morphogenic virus, the Female Changeling remarked she had not been able to change form for weeks.  ()

Personal interests 
Odo employed a number of tactics in his attempts to integrate with solids; for instance, he would often sit for quiet drinks with friends, and would create the illusion of drinking by forming part of his body into a cup of coffee and then drinking himself. ()

Thanks to the instruction of his people, Odo began to take a great interest in his abilities as a shapeshifter, and to explore the various forms and sensations he could experience while in his liquid state. He outfitted his personal quarters to this end. ()

When he was used as a host for the memories of Curzon Dax during Jadzia Dax's zhian'tara, Odo, after Curzon left his body, admitted to Dax that he had found Curzon's memories of various Humanoid activities such as eating, drinking, and playing tongo quite enjoyable, to the extent that he was amazed that Curzon had ever been able to get any work done. () Even prior to this, he noted that he was intrigued by the preparation efforts solids put into food, participating in Sisko's efforts to prepare a meal for the senior staff (). During his time as a solid, Odo learned to appreciate the simpler things in life. When Captain Sisko found Odo in Quark's, Sisko was surprised to find the constable was not on duty for once; he was instead studying a glass of sparkling wine. Odo observed how soothing the sound of the bubbles was. Although he had found ingestion a disgusting process at first, Odo told Sisko he had come to enjoy it. ()

Other aspects of monoform life proved less than comforting to Odo. In one embarrassing folly, he instinctively attempted to turn into a Vorian pterodactyl while chasing a criminal on the Promenade, but instead fell and injured himself. Additionally, he suffered from poor posture because he carried himself too rigidly for a normal humanoid. ()

Odo also had a penchant for the Earth sport of kayaking. He and O'Brien occasionally used a kayaking holoprogram, which O'Brien brought with him from the . Odo found the experience "quite enjoyable," although he refrained from singing sea shanties while they paddled. ()

Odo found humanoid death rituals fascinating, particularly the Ferengi tradition of vacuum desiccation. When Quark was selling discs of recently deceased Ferengi entrepreneur Plegg, Odo sarcastically informed Quark of his interest in the subject and offered to buy a disc, much to Quark's surprise. It turned out that Plegg was very much alive, and that Quark had been cheated. Plegg found this very amusing, although Quark and Odo did not. ()

During a baseball game between the Niners and the Logicians, Odo served as umpire, a position he found fascinating. He took his duties as umpire very seriously, to the point that he threw Sisko out of the game for breaking a rule, specifically, touching the umpire. Later, Odo also ejected Vulcan captain  from the game, for the very same reason. ()

Personal relationships

Family

The Link 
Although Odo was ostensibly an "orphan" from his beginnings of life in the Alpha Quadrant, Dr. Mora liked to think of himself as Odo's father and referred to himself as such on several occasions. Odo resented this presumption and preferred to forget his time in Mora's laboratory, mainly due to the various shock treatments he had been subjected to before it was realized that he was a sentient being. () When Mora helped Odo care for an infant changeling, the two of them bonded better, Odo realizing what Mora went through while "raising" him and understanding how hard it must have been for Mora when he left. ()

In a manner of speaking, all Changelings, and particularly the Great Link, were his family. He felt an irreconcilable estrangement from the Link when he discovered their hatred of the solids and that they were the leaders of the ruthless Dominion. ()

When arguing with a few Klingons, Drex asked in Klingonese if his mother let him talk to men. Elim Garak responded that he wasn't sure if Odo even had a mother. ()

Friendships

Quark 

From the time Quark opened his bar on DS9, he and Odo were constant antagonists. Regardless, they maintained a mutual respect for one another, and Quark once observed that as Odo's worst enemy, he was the closest thing the shapeshifter had to a friend. () Odo always kept a vigilant eye on Quark's illicit activities, but in many cases, he was able to use Quark's underground contacts to infiltrate criminal organizations to which he would not otherwise have access. ()

The two often had idle conversations at Quark's Bar while Odo was on duty and Quark was working. They maintained their rivalry yet were fond of each other's company and their regular exchange of insults. For example, Odo simply "hrmphed" when Quark, in his momentary capacity as Grand Nagus of the Ferengi Alliance, told him to kiss the Nagal staff, yet he was confounded by a sudden burst of cooperation in 2370, which was actually Quark's interpretation of the 76th Rule of Acquisition: "Every once in a while, declare peace. It confuses the hell out of your enemies". () During a temporary crisis in which a group of non-corporeal beings caused people's wishes to come true, Odo amusingly wished Quark into a holding cell without thinking about it. ()

More than anyone else, Quark knew about Odo's secret feelings for Kira and confronted him about them several times. It was Quark who told Odo that Odo was in love with Kira, breaking through the defenses Odo had carefully erected to keep his personal life private. Odo did not want Quark's sympathy, but when Kira officially began dating First Minister Shakaar, it was Quark who came to his quarters to check on him. There, he set Odo straight, although with the usual facade; Quark ran a regular betting pool on how long it would take Odo to catch a perpetrator, and he claimed his profits would suffer if Odo did not rectify things and get back to work.

By choice, Odo's quarters were directly above Quark's, and at times he took perverse (albeit secret) pleasure in annoying the Ferengi by practicing his shapeshifting skills during the night. Whether it was a Takaran wildebeest or a Rafalian mouse, Odo was able to annoy Quark whenever he felt like it. Once he set aside his feelings for Kira and got on with his life, Odo conveniently had his floor reinforced. As this would also soundproof the floor, Quark saw that his advice had helped and thanked Odo. ()

In a mental recreation of Terok Nor during the Occupation, Odo (seen as a Bajoran) had to do subsidiary work at Quark's Bar which he felt quite humiliating. He asked Captain Sisko "How much damage would it do to the timeline if Quark were to suffer a mysterious... accident?" ()

Quark and Odo managed to get along briefly while trapped on an inhospitable planet and under dire circumstances; they resumed their old rivalry as soon as they returned to DS9. ()

When Laas visited the station and was detained for "the fog episode" on the Promenade, Quark later came to Odo to explain to him "You're smart enough to know that people don't want to be reminded that you're different", in a seemingly friendly way. ()

When Odo left DS9, he attempted to do so without anyone noticing, but Quark caught up with him in the airlock. Odo claimed to have nothing to say to the Ferengi, but while he did not say so, it was clear Odo would miss his long-time adversary. When Kira tried to apologize for Odo's coldness, Quark said "That man loves me – you can see it written on his back". He later admitted to Kira before entering the Great Link that he would miss everyone aboard DS9, even Quark. ()

Worf 

Worf and Odo both enjoyed their privacy, and they shared a dislike of unexpected visitors. Although the two of them did not become close friends (as was the case with most of Odo's friendships), Worf and Odo respected and understood each other, as in many ways they had similar personalities.

The two of them clashed while Worf was attempting to acclimate himself to life aboard DS9. Worf observed that Quark was conducting smuggling activities and informed Odo about it only to find that Odo already knew of the transactions. Unknown to Worf, Odo was conducting an undercover operation and planned to use Quark's clandestine connections to infiltrate a large smuggling ring. When Worf placed Quark and Quark's contact under arrest, he discovered that the container in which the payment for the illicit goods were located was actually Odo in disguise. ()

Worf and Odo occasionally argued over the laxness of security on DS9. On one occasion, when Worf apprehended a Dopterian who had stolen items from Worf's quarters, he asked Odo why he "allowed" such security breaches to occur. Odo responded by citing a number of security breaches aboard the  before Worf told him to stop. () 

Once the two learned each other's ways, they found they could relate to one another far more than they realized. Odo offered Worf advice on how to keep people from simply "dropping by" his quarters. ()

Miles O'Brien 
Miles O'Brien and Odo had a good working relationship. Odo volunteered to represent O'Brien when he was tried in a Cardassian court, successfully proving O'Brien's innocence despite the Cardassian legal structure regarding the trial as a mere formality for a pre-determined sentence. This trial gave Odo the opportunity to get to know O'Brien better and develop an admiration for his strong sense of duty when he proclaimed that he had always tried to be somebody his children could be proud of. A couple of years later, he allowed the O'Briens to return the temporally-displaced Molly O'Brien to Golana, even though they broke her out of a holding cell. He joked that he was actually disappointed as he expected O'Brien to succeed in breaking someone out of the station without being discovered. ()

At one point, Garak made mention that O'Brien shared "Human crime novels" with Odo; he stated that they may have been influencing Odo's thinking. ()

O'Brien and Odo went kayaking in a holosuite several times; an activity Odo found "quite enjoyable". () Odo (or the impostor Changeling trying to pass as him) tried to use knowledge of details from their most recent trip to prove he was the real Odo. ()

Garak 

Garak and Odo were forced to work together during the events leading up to the joint Tal Shiar-Obsidian Order strike on the . What began as a decidedly unwilling partnership, evolved into a mutual respect as Garak began to understand that, unlike his other erstwhile sparring partner Doctor Julian Bashir, Odo truly understood who Garak was. Strangely, Garak's attempt to torture Odo while trapped on the Tal Shiar ship created a mutual understanding and a peculiar bond between them. Garak recognized that he no longer had the will to torture those he was close to, and Odo empathized with Garak's willingness to do anything to return to his own people. They later had many quiet "drinks" together. () 

Garak once attempted to set Odo up with a date with Chalan Aroya but was ultimately unsuccessful. ()

Benjamin Sisko 

Although Odo noted that he didn't think he would like Benjamin Sisko when he first met him, the two formed a keen respect for each other over the years. When Sisko was promoted to captain, Odo noted that, while he didn't personally see the relevance of such titles, he could think of nobody who deserved this ritual more than Sisko. Sisko reciprocated this admiration more than once. When Odo's life was at stake following his capture by the Obsidian Order and later his illness, Sisko took the Defiant into Dominion territory to save Odo, despite the risks of conflict with the Dominion. Odo also accompanied Sisko back to Earth when they received news that the Changelings had reached Earth. He helped him develop means of detecting Changelings on the planet. On another occasion he helped Sisko, who was falsely accused of being a Changeling by Admiral Leyton, escape. ()

Laas 

While on a routine mission in the Alpha Quadrant, Odo and Chief O'Brien happened upon another Changeling named Laas. Odo was fascinated, as Laas too was one of the hundred infant Changelings the Founders had sent out to learn about other civilizations. The two of them bonded quickly, and Odo was able to tell that Laas' intentions were good despite the chief's concerns.

Laas did not integrate well when they returned to the station. He openly stated his dislike of "solids," much to Odo's chagrin. Laas believed Odo had been brainwashed into acting and thinking like a solid, making excessive and disruptive use of his own shapeshifting abilities to prove his point. Ultimately, Laas left in search of other Changelings in order to form a second Great Link. ()

Romance

Kira Nerys 

Over the years, Odo began to fall in love with Kira Nerys. He kept this a secret from her, and stood by as she entered into and ended other romantic relationships, including the death of Vedek Bareil Antos. After Bareil's death, Kira took up a relationship with Shakaar, the head of the Bajoran government. Although she eventually learned his true feelings after an encounter with an alternate future version of him, Kira and Odo were left reluctant to pursue a relationship at the time, due in no small part to the future Odo having erased over eight thousand people from existence simply to prevent Kira's death in his original timeline and give his younger self another chance with her. Eventually, with the help of Vic Fontaine, he finally revealed his feelings for her in 2374, Kira reciprocating his feelings. Despite this, Odo left Deep Space 9 at the end of the Dominion War to heal the Great Link of a virus that was killing the Changelings and showing them positive aspects of the solids. ()

Lwaxana Troi 

Ambassador Lwaxana Troi was infatuated with Odo from the moment she saw him. As she put it, "I've never been with a Changeling before!" Odo found Lwaxana's advances annoying and even complained to Commander Sisko that Ambassador Troi wouldn't leave him alone. An accident trapped the two of them in a turbolift together shortly before Odo was set to revert to his gelatinous state. Over the course of several hours, the two of them began to understand each other better.

They were stuck in the turbolift so long that Odo could barely hold his shape and was literally "melting." Lwaxana offered to carry Odo in her dress, but he was embarrassed and worried, as no one had ever seen him in his liquid form. He was worried that if someone saw him like that, they would be repulsed because he was so different from them. To make him feel understood, Lwaxana removed her wig and admitted that no one had ever seen her in her natural state either. Odo felt more at ease after this revelation and allowed Lwaxana to carry him. Their interaction had a profound effect on Odo, giving him more confidence in who he was. ()

During Ambassador Troi's next visit to DS9, her persistent feelings for Odo combined with a case of zanthi fever caused people in close proximity to her to desire others: Jake Sisko and Doctor Bashir both became infatuated with Kira, for example, Jadzia Dax with Sisko, and Vedek Bareil with Dax. ()

Lwaxana's final visit with Odo was when she fled her Tavnian husband, Jeyal, who was intent on taking her unborn child when it was born. In Tavnian culture, boys and girls were raised under strict gender separation, something Lwaxana's husband had initially promised would not be the case for their child (he later declared his intention to take her male child as soon as it was born, disregarding his previous assurances to her). Lwaxana had married Jeyal in response to being rejected by Odo and having her heart broken. She had come to Odo for protection from her husband and Odo came up with the plan to marry Lwaxana in Tavnian tradition in order to end the biological father's legal claim to their offspring under Tavnian law (which specified the mother's husband as the legal guardian for male children). This required a public profession of his love for her, which needed to be believable. While Odo wasn't romantically attracted to Lwaxana, his profession of love for her was genuine, revealing the depth of appreciation he had for her and their friendship. Reflecting on their relationship since their time stuck in the turbolift a few years before, he said, "Before I met her ... I was ashamed of what I was, afraid that if people saw how truly different I was they would recoil from me. Lwaxana saw how different I was and she didn't recoil. She wanted to see more. For the first time in my life, someone wanted me as I was. And that changed me forever. The day I met her, is the day I stopped being alone. And I want her to be part of my life from this day on." The plan was successful and Lwaxana was free from Jeyal. Odo wanted her to stay on DS9 following their marriage, but Lwaxana knew Odo's love for her wasn't romantic and she would come to resent him for not reciprocating her love. Their friendship was too precious, she said, to allow that to happen. ()

Arissa 

An Idanian woman named Arissa once fell for Odo while he was protecting her from the group who were trying to kill her, the two even spending the night together (a first for Odo, outside of a single pseudo-sexual encounter during his brief time on the Founder homeworld). Later, he found out that she was an agent sent into deep cover to infiltrate the Orion Syndicate. She was married and, due to her mind having been altered to escape telepathic examination, she did not know this while she was undercover. As she departed to return to her former life, she assured Odo that she had genuinely loved him in their time together and in a way still did. ()

Female Changeling 
When Odo first visited the home of his people the Changeling representing them took the form of a female humanoid. The two linked together in a way that might be considered sexual. () Later, during the Dominion's occupation of Deep Space 9, Odo became involved with the Female Changeling. Initially, his only intent was to learn more about his own people and perhaps influence her towards a peaceful resolution of the current conflict. However, she was able to manipulate him and his desire for control over his own emotions regarding Kira. Eventually she was able to almost completely turn Odo away from his former friends and allies, but the revelation that she intended "to break" the Alpha Quadrant peoples of their desire for freedom shocked him into reconsidering his new "perspective". He effectively ended their personal relationship by siding once again with the Federation against the Dominion. () Later, at the end of the war, he was able to save her life from the morphogenic virus and convince her to give the stand-down order to the remaining Dominion forces by promising to return to the Great Link with the cure. ()

Chronology 
Unknown: Found adrift and in his gelatinous state in the Denorios belt, Odo is brought to the Bajoran Institute of Science to be studied by Doctor Mora Pol

2363: Guls Dukat and Hadar attend a reception at the Bajoran Center for Science to view Odo and his abilities. The Changeling performs the Cardassian neck trick, to wide acclaim

2365: Becomes an investigator on the Cardassian space station Terok Nor

2366: Is designated an officer of the Cardassian court, in order to testify in criminal cases

2369: Becomes chief of security when Terok Nor is transferred to Federation control as Deep Space 9. He learns he originated in the Gamma Quadrant

2371: Discovers the Great Link, and later becomes the first Changeling to kill another

2372: The Great Link sit in judgment of him, and render him "solid"

2373: The dying act of an infant Changeling is to make him a Changeling once more

2375: Leaves DS9 to rejoin his people in the Great Link

Alternate realities and timelines 

In an alternate timeline in which Harry Kim was never assigned to the , Odo arrested Tom Paris in 2371, after Paris attacked Quark in Quark's bar. Odo's actions during this incident resulted in Paris still sitting in a holding cell on DS9 when Voyager was thrown into the Delta Quadrant. Odo was later mentioned by Paris, in conversation with Kim, at which point Paris described him as "a very unpleasant shapeshifter." ()

In an alternate timeline in which the Defiant was sent back in time to the 22nd century, Odo was the only member of the crew (besides Dax) who lived to see the Defiant arriving in the 24th century. In two hundred years, he had grown more proficient in shapeshifting and was able to assume a more humanoid face. Odo, during the Defiants visit in the 24th century, admitted his romantic feelings to Kira, and subsequently linked with his younger self. He sabotaged the Defiant and caused it to avoid crashing on Gaia, wishing to give his younger self and Kira a second chance at love. By doing so, the inhabitants of Gaia ceased to exist. ()

Holograms 

Odo was holographically duplicated at least twice.

Luther Sloan recreated the entire station, and staff, of Deep Space 9 in 2374 as part of his investigation into Julian Bashir, including Odo. ()

The 's computer chose a holographic Odo as as a member of Dal's command crew during his attempts at taking the . ()

Memorable quotes 
"You can tell a man's intentions by the way he walks."
 - Odo ()

"Hmgh..."
 - One of Odo's catchphrases

"They were an ecological menace, a plague to be wiped out."
"Wiped out? What are you saying?"
"Hundreds of warriors were sent to track them down throughout the galaxy. An armada obliterated the tribble homeworld. By the end of the 23rd century, they had been eradicated."
"Oh, another glorious chapter in Klingon history. Tell me, do they still sing songs of the Great Tribble Hunt?"
 - Worf and Odo, on tribbles ()

"Come on, Quark, move it along. You should be in the emergency shelter by now."
"I'm not going to any emergency shelter. This is my bar, and I'm going to defend it."
"Really? And how do you plan to do that?"
"With this."
"You're going to hit them with a box?"
"No. This is my disruptor pistol. The one I used to carry in the old days, when I was serving on that Ferengi freighter."
"I thought you were the ship's cook."
"That's right. And every member of that crew thought he was a food critic. If the Klingons try to get through these doors, I'll be ready for them."
(reads note in the empty box) "Dear Quark, I used parts from your disruptor to fix the replicators. Will return them soon. Rom."
"I will kill him!"
"With what?"
 - Odo and Quark ()

"You are a thief!"
 - Odo, to Quark ()

"All right, let's try again. Close your eyes, take a deep breath... clear your mind of anything in it... if there's anything there..."
 - Odo, trying to spark Rom's memory ()

"QQUUAARRKK!!!!"
 - Odo ()

"Someone's extracted all the latinum! There's nothing here but worthless gold!"
"And it's all yours."
 - Quark and Odo ()

"It's just Quark's luck that you would be assigned quarters right above his."
"Luck had nothing to do with it."
 - Kira and Odo ()

"But don't worry – I plan to investigate the Klingons, the Bajorans, Quark, the visiting Terrelians..."
"You think Quark had something to do with this?"
"I always investigate Quark."
 - Odo and Sisko ()

"I have a friend at Starfleet Intelligence. And she has a friend who has a cousin who's married to the assistant of one of the members of the Federation Medical Council."
"Really?"
"And according to my friend, her friend heard something from his cousin that his wife heard from this council member that I thought you might find interesting."
"Which is?"
"Doctor Wade is not going to win the Carrington."
 - Odo and Bashir ()

Appendices

Background information 
Odo was played by Rene Auberjonois throughout the entire run of . Odo has also been played by Salome Jens (when he took the form of the Female Changeling in  to infiltrate a Jem'Hadar ship), several unnamed animals (including rats, birds, and a German Shepherd), and various inanimate objects.

As Michael Piller explains, "we needed a character who represented the traditions of Spock and Data, the outsider who looks in at humanity." (New Frontiers: The Story of Deep Space Nine, DS9 Season 2 DVD, Special Features) He described Odo as "the curmudgeon of all curmudgeons. So instead of Data who worships humanity and wants to be that, and Spock who would deny it, Odo has been forced to pass as a humanoid all of his life, to look like us and act like us because it's a lot more socially acceptable and he resents it. So he has now found a way to use it as a defense mechanism and keep a distance from it and find ways to be critical of the human condition." (Trek: Deep Space Nine: The Unauthorized Story, p. 10)

[[File:Odo concept art.jpg|thumb|Concept art for "a much more muscular, intimidating lawman" version of Odo" (Star Trek: The Magazine, Issue 5, p. 22)]]
The original 1992 Writers' Bible for Star Trek: Deep Space Nine gave this biography for Odo:
Odo, an alien male, middle-aged curmudgeon, and a shape-shifter. In his natural state he is a gelatinous liquid. He was Bajoran law enforcement officer on the space station under the Cardassians. Starfleet decides to have him continue in that role, since he's extremely savvy about the Promenade and all who frequent it. His back story is: 50 years ago, with no memory of his past, he was found alone in a mysterious space craft that appeared in the Denarias asteroid belt. He was found by the Bajoran and lived amongst them. At first he was sort of an Elephant Man, a source of curiosity and humor as he turned himself into a chair or pencil. Finally he realized he would have to take the form of a humanoid to assimilate and function in their environment. He does it, but resents it. As a result, Odo performs a uniquely important role in the ensemble: he is a character who explores and comments on Human values. Because he is forced to pass as one of us, his point of view usually comes with a cynical and critical edge. But he can't quite get it right, this humanoid shape, though he continues to try. So he looks a little unfinished in a way. He's been working on it a long time. Someone might ask him: Why dont you take the form of a younger man. His answer: I would if I could. He has the adopted child syndrome, searching for his own personal identity. Although he doesn't know anything about his species, he is certain that justice is an integral part of their being, because the necessity for it runs through every fiber of his body – a racial memory. Thats why he became a law man. He has a couple of Bajoran deputies; he doesnt allow weapons on the Promenade, and once every day he must return to his gelatinous form.

According to Rene Auberjonois, "Constable Odo was envisioned originally as a kind of young John Wayne sheriff-in-town." Similarly, Ira Steven Behr stated, "I was told six months before the series began that Odo was going to be a  type, and when we started creating the first couple of episodes, we sent writers off to write Clint Eastwood. And then I was told Rene Auberjonois. And I said, 'Clint Eastwood, Rene Auberjonois? Clint Eastwood, Rene Auberjonois? Does not compute.' And then I saw what he brought to the role, and I had to call up a whole bunch of writers and say 'Guys, I apologize, but this is better than we even imagined." (Crew Dossier: Odo, DS9 Season 3 DVD special features)

Although Rene Auberjonois himself was initially unsure as to whether or not he could play the role, his daughter had no such doubts: "When the script was first sent to me and I read the description of the character, my daughter said to me, 'Oh dad, yeah, this is yours, you're gonna get this.' My kids were completely confident that this part was for me, which, considering the nature of the character, I don't know if I should take that as a compliment or not." (Hidden File 04, DS9 Season 1 DVD special features)

Auberjonois was not allowed to eat or chew gum while filming, for fear it would ruin the make-up, although Salome Jens managed to get away with chewing gum on the set. Subsequently, Auberjonois said that "now I chew gum as a tribute to Odo." 

The name "Odo" is shared with a central character in 's 1974 novel . The character, ironically and in contrast to the Odo of Deep Space Nine, is an anarchist. Michael Piller originally called the character "Otto", but Rick Berman changed it to "Odo". (New Frontiers: The Story of Deep Space Nine, DS9 Season 2 DVD special features)

Odo's relationship with Quark is a clear homage to the classic 1942  film , with Odo in ' role of Captain Louis Renault and Quark as 's Rick Blaine, although the garrulous Renault and taciturn Blaine are somewhat the opposite in personality to their counterparts. At one point Quark notes, "Everybody comes to Quark's," a nod to the title of the play on which Casablanca is based (Everybody Comes to Rick's by  and ), while, in , he asks, "Do you think this is the beginning of a beautiful friendship?" a twist on the film's closing line.

Several scripts refer to Odo's superior strength, such as ,  and his lack of a sense of smell. ()

Mary Chieffo once remarked, "Of course, I have a soft spot for Odo." 

 See also 
 Odo 1, a combat training holoprogram
 Odo's bucket
 Odo One, a program used to drive away the Saltah'na energy spheres

 Apocrypha 
In the Star Trek: Deep Space Nine - Millennium series of novels, it was revealed that Odo rarely shifted into smaller forms such as insects due to a psychological block from his original "training" under Doctor Mora; Mora once speculated that Odo's excess mass during small transformations was transferred to a pocket dimension, and Odo initially worried that something might happen to his mass if he maintained a small shape for long. The same novel series also speculates that the Founders placed a mental block on Odo's abilities to make it difficult for him to alter his face, thus explaining why he can never get faces quite right, even after linking with other Changelings on several occasions.

In the DS9 Relaunch novels, Odo sent a Jem'Hadar ambassador to the Alpha Quadrant to foster understanding in the Dominion of other cultures. He soon returned to DS9 and reunited with Kira.

Odo later learned that the Hundred were initially sent out to find the Progenitor – the first Changeling and the key to solving their declining population, as Changelings could not reproduce (Odo and the other Hundred were not "infants", but merely Changelings that had never been part of the Great Link) – but the discovery of the Progenitor's death caused the Changelings to disperse across the quadrant. As of 2382, Odo had only rediscovered approximately thirty Changelings, including himself and Laas, to form a new Link.

According to the Star Trek: Terok Nor novel Night of the Wolves, Odo was found in a spherical module in the Denorios Belt by the Cardassian vessel Kevalu, which was under the command of Dalin Malyn Ocett, in 2345.

In the Star Trek: Typhon Pact novel Raise the Dawn, Odo returned to the Alpha Quadrant to help Sisko investigate reports that the Typhon Pact, an alliance of the Federation's enemies, have stolen Jem'Hadar technology to perfect their own quantum slipstream drive, only to be trapped in the Alpha Quadrant when the wormhole was seemingly destroyed thanks to Kira's attempt to stop a Typhon Pact ship from using it again. Sisko offered Odo a place on his new ship, the USS Robinson, but the novel ends with Odo deciding to remain on Bajor for a time to think about what he will do next.

In Star Trek Online, Odo makes a sudden appearance at the very end of the mission "Scylla and Charybdis" when Dominion ships race in to aid the Alpha Quadrant Alliance in protecting Bajor and the heavily damaged Deep Space 9 from a fleet of Hur'q ships, only cryptically telling the player character "We have to talk." Odo plays a major role in the "Victory is Life" expansion, voiced again by René Auberjonois. In the introductory missions for new Jem'Hadar characters, set immediately before "Scylla and Charybdis", Odo instructs his Vorta advisors Weyoun and Loriss to lead his Vanguard Fleet through the wormhole to Bajor. He calls a conference on DS9 and informs the delegates that the Dominion fleet, save for his Vanguard, has all been destroyed by the Hur'q, and calls for the Alpha Quadrant powers to join him in combating the threat. In the course of events in the Gamma Quadrant, Odo admits that he has secretly used transponders to purposely lure the Hur'q to various worlds, including Bajor, to convince the other powers to fight them alongside the Dominion, and reveals that he has been kept in the dark by the Female Changeling and the rest of the Great Link in regards to their threat. In the mission "Home", Odo personally leads the defense of the  of Empersa, and later brings the Dominion officially into the Alliance.

The alternate reality version of Odo appears in the Star Trek: Ongoing story arc The Q Gambit where he is a member of the Free Federation Resistance after being found by Resistance scientists in 2348. Odo helps Sisko, , , and  escape from Terok Nor by posing as a Jem'Hadar and are then beamed aboard the USS Defiant'' where they head for Earth, which had been taken over by the Klingon Empire and renamed "Tera'." When Kurn escorts the group to meet with Chancellor Worf, Odo tells Sisko that something felt amiss to him, and he was right when Worf is suddenly killed by his guards and Kurn, but it is revealed that they're actually Changelings who proclaim Earth is now under Dominion control. One of the Changelings then points his disruptor at Odo saying he would have the honor of dying first for betraying his people, to which Odo said he would commit the betrayal a thousand times over as they have twisted their once peaceful civilization into a mockery of all that is honorable. They are saved when a shuttlecraft piloted by Miles O'Brien arrives and causes the ceiling to crumble killing the Changelings. Odo then explains that he arranged for the shuttle to come pick them up but couldn't risk telling Sisko in case their enemies found out. When they meet up with Jake Sisko and Jadzia Dax on the Resistance outpost planet Paradise, Sisko becomes host to a Prophet and Odo explains to Uhura who the Prophets are.

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