Its pretty simple honestly, My Mother adopted a little girl, in one of those, give them something to take care of and it'll teach them compassion, type things, I didn't really understand it then.
Anyway, I took care of her, not out of care, but because the one who gave me life told my to, obligation, until one day she was attacked by someone....
That's when it happened... The panic, the anger, and the rush of adrenaline. I killed that man, and because of how young I was, and how little I understood about emotion, I decided that the good feeling I felt afterwards must have come from killing....
Of course, now I'm not an idiot, I know the feeling was actually relief that someone I cared about was safe, but by the time I realized that the damage was already done, my mind associated killing with some sick form of happiness...