Subject 13, a male Rakata, was born in the era of the Infinite Empire. He was designated with this name because twelve prior attempts had failed, making him the thirteenth subject and deemed a success. This Rakata possessed a notable strength in the Force, resulting in his confinement within a Mind Prison. This prison was located on the prison planet of Belsavis, where he remained captive for countless centuries. His very being was so potent that it permeated the Mind Prison, even preventing him from ending his own life and guaranteeing his continued imprisonment.
During the Cold War era, the Galactic Republic prison known as the Tomb was under siege by the revived Sith Empire. It was during this conflict that Sith Lord Mohgren discovered Subject 13. He then tasked Imperial forces with searching the uncharted areas for the Rakatan Mind Prison. The goal was to liberate Subject 13 and subsequently manipulate him into serving the Empire's purposes. An Imperial operative entered the Mind Prison, where Subject 13 attempted to transfer his consciousness into their body, seeking freedom from his confinement. The Imperial was subdued and weakened, but immediately afterwards, Suvaar, Mohgren's apprentice, entered the Mind Prison. Following his master's instructions, Suvaar willingly surrendered his body to Subject 13, allowing him to return to the physical realm.