Because Shinichi was able to prevent Migi from traveling further up into his brain, both beings retain their separate intellect and personality. As the duo encounters other Parasites, they capitalize on their strange situation and gradually form a strong bond, working together to survive. This gives them an edge in battling other Parasites who frequently attack the pair upon realization that Shinichi's human brain is still intact. Shinichi feels compelled to fight other Parasites, who devour other members of the species they infect as food, while enlisting Migi's help.