Ruon Tarka
Doctor Ruon Tarka was a Risian Federation scientist who lived during the late 32nd century.

History 
Tarka showed signs of a genius-level intellect at an early age. He felt he was never understood growing up on Risa, believing he was "surrounded by idiots". In his first scientific experiment at the age of five, he atomized a live caracal to prove a theory. ()

Emerald Chain 
Tarka was enslaved by the Emerald Chain and implanted with a control device on the back of his neck. He had been employed by Osyraa to seek out an alternative to dilithium in the wake of the Burn, and spent four or five years in solitary confinement working on the problem.

Eventually, he was paired with another scientist, Oros, who became a close friend by the end of the first year. Inspired by Oros' "relentless optimism", Tarka began looking into alternate universes, and together they found one where there was no war, no Burn, no Emerald Chain to enslave them, a place Oros called "Kayalise", from the legends of his people. After nearly two years, they constructed an interdimensional transporter, but the power supply was too low, and their initial escape was unsuccessful. Tarka ended up having to leave Oros behind when he escaped the Chain. They both made a promise to one another to meet in Kayalise. He kept the scar left behind after his control device was removed, as a reminder of his grief and of the promise he had made. ()

Working with the Federation 
In 3180, Fleet Admiral Charles Vance saw Tarka giving a lecture on speculative propulsion and power technologies. Judging him to be one of the most brilliant minds he had ever encountered, Vance brought Tarka into his confidence, giving him free rein and virtually no oversight. ()

By 3190, Tarka was considered an expert at the leading edge of both Federation and non-Federation technology, and headed a number of scientific endeavors for the Federation. One project of particular interest to the Federation was the next generation of the displacement-activated spore hub drive, based on Commander Paul Stamets' work aboard the . Tarka worked with ex-Emerald Chain scientist Aurellio, who acted as a middleman between him and Stamets, as Tarka always claimed to be "too busy" to speak to Stamets directly.

Following the discovery of the Dark Matter Anomaly, an artifically created phenomenon of immense power, Fleet Admiral Charles Vance requested Tarka's services as an advisor to Starfleet to counteract the threat. Tarka boarded the Discovery to work in concert with Stamets. Based on previously gathered data, Tarka theorized that the DMA had been tunneled through spacetime by its unknown creators, and proposed creating a scale model of the device believed to be controlling the anomaly and generate a miniature DMA inside Discovery. Though both he and Stamets were convinced the model would provide the answers they sought, Captain Saru aborted the experiment before the containment field around it failed and threatened the ship. Nevertheless, based on the model data, Tarka postulated that the energy source for the DMA was equivalent to that of a hypergiant star. ()

Going rogue 
During a summit meeting with the various members of the United Federation of Planets and their allies, Tarka interrupted the meeting, talking down various members in their failures in either damaging or studying the anomaly before revealing he had a plan to deal with it: with the aid of Discovery, they could drop a special weapon inside a safe spot within the DMA and detonate it, dissipating it. Realizing that it would use an isolytic burst to do so, Captain Michael Burnham quickly tried to shoot the idea down, noting it could damage subspace and prevent warp travel. However, Tarka had a surprising ally in the form of Cleveland Booker, Burnham's boyfriend and the last known surviving Kwejian, who Tarka knew was capable of navigating with a spore drive; Booker, vengeful at the loss of his homeworld, believed Tarka's plan was the only one that made sense. After the summit voted instead to pursue peaceful first contact with the unknown species behind the DMA, Tarka stole the prototype for the next-generation spore drive and installed it on Booker's ship, and Booker used it to jump away from Discovery. ()

Tarka and Booker were both placed on the Federation's watch list for theft of classified Federation technology and conspiracy to undermine an official act of the Federation. Tarka had initially planned on obtaining the isolynium required to construct an isolytic weapon through Federation channels, but with the summit voting against him, he now had to rely on Booker's courier expertise. Despite a run-in with Burnham at Haz Mazaro's Karma Barge on Porathia, they were able to obtain the isolynium, allowing Tarka to build the weapon. ()

After completing the weapon, Tarka became increasingly impatient with Booker's focus on Burnham and the Discovery crew, warning that Booker would have to choose between his feelings for them or stopping the DMA. His impatience turned into outright hostility when they were confronted by Discovery while preparing to deploy the weapon, firing a full spread of quantum torpedoes at Discovery to try and stop them. Booker was ultimately persuaded by Burnham to stand down, but Tarka went ahead anyway, beaming the isolytic weapon directly into the DMA controller, with a null-space bubble to protect the controller's power source. While it seemed to succeed in destroying the DMA, Tarka was stunned to realize that the power source was not present, leading him to realize the DMA was being powered from the other side of the wormhole by Species 10-C, outside the galaxy. Worse, his effort to destroy the DMA proved temporary, as a new DMA appeared in its place not long afterward. ()

Tarka remained obsessed with his goal, and traveled back to the Emerald Chain camp that he had escaped from a decade before to find a stash of programmable antimatter that would allow Booker's ship to travel through the galactic barrier to locate the DMA power source. With it, they were able to reach the barrier and follow Discovery through. ()

In orbit over the Species 10-C homeworld, Tarka suggested a plan in which he would install a patch in Discoverys engineering section that would allow them to escape detection by Zora, the sentience that resided in the ship's computer systems; this would allow Booker's ship to attach to Discovery as it entered the hyperfield that contained the 10-C and the DMA power source. He was caught by Commander Jett Reno, one of Discoverys engineers, and was forced to take her hostage when he returned to Booker's ship. ()

Reno challenged Booker to ask Tarka about the calculations, as she had seen that his effort to remove the DMA power source from its silicon-ellanium casement would destroy the hyperfield, taking the 10-C, Discovery, and Booker's ship with it, and the backlash with the DMA active would devastate Earth and Ni'Var. Tarka admitted the possibility, but did not wish to add to Booker's hardships; nonetheless, he remained focused on his goal. When Booker moved to stop him, Tarka showed that he had taken complete control of the ship's systems. ()

With Booker's ship under his control, Tarka proceeded towards the power source and began to extract it from the casement with a gravimetric beam. Booker, using one of his cat Grudge's collars to disrupt holo-projectors, escaped from the forcefield Tarka had put him and Reno in and knocked out the scientist, but was unable to restore systems in time. When he returned to consciousness, Tarka tearfully admitted that Oros would have stopped him from doing what he was, just as Booker had been trying to do. He had locked the computer with a fractal encryption code, and there was not enough time to crack it. General Ndoye, who revealed the truth to Burnham aboard Discovery, piloted a shuttle into Booker's ship, disabling the gravimetric beam and sending it careening towards the edge of the hyperfield. Tarka diverted enough power to beam Booker to safety, telling him that his life awaited him in this universe, while Tarka's awaited him in Kayalise. Tarka was attempting to use his interdimensional transporter to transport to his new home when Booker's ship was destroyed on impact with the hyperfield, leaving the scientist's fate uncertain. ()

Appendices

Appearances

Background information 
Ruon Tarka was played by Shawn Doyle.
Risians
Scientists