I try to make all the characters in my writing into real people, you know, the way you do. Because no one is interested in reading about propped up bits of painted cardboard.
But when you (and by “you” I mean “I”) start delving into the heads of violent antagonists in an attempt at fleshing them out, when you start understanding who they are and why they are the way they are, you start maybe sympathising, just a bit, with their worldview. At least when you’re looking at their world through their eyes.
And you start, maybe, liking them. Just a little. Or more than just a little.
Which can be damned disconcerting, considering the nasty things they do.