Harris had distinguished himself with training, in part from Alfred Bester, in basic psionics, op research, deep scan 2, interrogation, block dev 2, and field tech. He was also trained in attack probes, with a knack for disrupting other telepaths – a mindshifter.
In 2262, Harris had an accident during an off-hours training with his roommate. His roommate accidentally saw Harris' other personality, which caused Harris to freak out. As opposed to Harris' measured P10 ability, the other identity, referred to as "the dark man," was a P12. Soon after that incident, "the dark man" killed Harris' roommate and traveled to Babylon 5, driven to escape. There, he gained money by killing a gambler and taking his skills from his mind, hustling other gamblers. One gambler confronted him, and he killed that man, too, causing several aneurysms in his brain. He entered into an arrangement with another human named Bryce to earn more money but they were both intercepted by B5 security, as well as Bester himself. He refused to return to the Psi Corps, but collapsed into a confused state and was arrested.