After turning Scott into a werewolf, in that first primal rage he experienced from the transformation, Silvia sicked him on Liz as her first prey. Once gaining some consciousness he was filled with remorse, meanwhile Silvia was filled with blood and flesh. Horrified by his actions he stowed away in a dark corner only to have the room dimly lit from an otherworldly glow, Liz's soul had manifested into a ghost, as a ghost she can phase through walls and shapeshift. Liz's mission is simple, guide Scott so he doesn't slaughter innocent lives and annoy the shit out of Silvia.