As a male Human and a member of the Mantellian Separatist faction, Jex participated in the Separatist War. This conflict pitted the Galactic Republic, supporters of the Ord Mantell Central Authority, against the Separatists. Jex was stationed at the Separatist Base located at Mannett Point. During a mission, a sergeant of Havoc Squad infiltrated this base. The sergeant encountered Jex and his injured Separatist comrades, but the sergeant allowed them to leave with the understanding that they would cease fighting.
Jex's initial appearance was within the narrative of Star Wars: The Old Republic for the Republic Trooper storyline. His voice was provided by Erik McDowell.