[@ZayZe] that! Or maybe a friend of his from way back when. One who was with him during a bad time in his life?

Idk just an idea. I was thinking about still having her kill her sister which would make her more inclined to want to flip her switch so she doesn't have to feel that pain anymore. 

Lucio's been alive for a while, he's gotta have some enemies, old lovers, and friends. Maybe he went through a ripper phase or something? XD Idk like you said just all ideas you can dismiss or take/expand off of!