SARA_ROSE, you said, that a serial killer couldn't be likeable, so i'll give you an example of how i would get affection or at least compassion for a serial killer.
if my child was attacked and killed ( i won't go into detail but you get what i mean ). i decide that every peopdophile should die, so i go out and become a vigilante, killing a multiple number of these types. To the police i would be a serial killer, to others i would be a hero, or at least they could understand my reasons. I believe psycotic behaviour can be aroused in any of us, it just takes a number of extreme circumstances to occur in our lives.
that's why i made the point about "what is right or wrong", as i see these are the areas that could be manipulated.