Nyris Ko, a Cathar of the female gender, existed in the era of the war against Zakuul. After the Eternal Empire's Empress, Vaylin, met her demise and the Eternal Alliance was established in 3630 BBY, she, along with her relative Icarr Ko, became part of Doctor Alirra Semhess's renegade Republic scientists. This group was secretly working on a project aboard the X7-Cratus space station. Theron Shan, leading Eternal Alliance operatives, uncovered Semhess's clandestine operation, which prompted the deployment of a strike force to X7-Cratus. Their mission was to prevent RS-33 adrenal from posing a galaxy-wide danger. Alliance forces clashed with and overcame Marlon Fenn, but this encounter led to damage in the station's containment infrastructure, causing RAK-5 serum to escape into the air. Icarr and Nyris Ko confronted the intruders while in an infected condition, and after transforming into rakghouls during the battle, Alliance personnel eliminated both of them.