Pvt. Katie's real name is actually Katie W. Lynn. She was 19 years old at the begining of the outbreak. She was in the marines for 7 months, before she took a bullet in the leg, causing her to be discharged. She later joined the C.A.P. for Northern Washington, but soon after moved to Boise, and joined up there.
Katie almost immedietly drove back to Washington, where she hung out with the C.A.P. there for a while, getting back into her old life. She never went back to her apartment in Boise, but wants to go back there badly, because she left everything there except her trusty Desert Eagle, Bertha, and a few boxes of ammo.