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Lisa Mannix was a marine in the Sons of Korhal, later defecting with Jim Raynor. Calm and efficient, she never seemed to get riled up. Off duty, she was calm, easygoing and almost playful. On duty however, she was "all business".
Originally a member of the Sons of Korhal, Lisa Mannix abandoned the group after the Fall of Tarsonis, unable to stomach what the SOK had done to the planet. As such, she followed Jim Raynor, joining his group Raynor's Raiders.
Roughly two months later, the Raiders arrived at Char and sent down a ground force to locate captured terrans. Sergeant Mannix (one of several sergeants) acted as the ground force's second-in-command, organizing it into small units. Descending into a series of tunnels, Mannix fought the zerg as she and the rest of the force progressed through them. In one firefight, she was forced to shoot fellow soldier Private Lance Messner as he was being literally ripped apart by zerglings. She also supported Raynor by dazing opposing zerg with thrown grenades.