I've always found it weird that in movies and even in cartoons, many people are presented with this bumbling, inept portrayal of evil, of people who wish to harm others, but somehow just don't quite cut it, while the "good" characters and heroes are always smarter than the bad guys, but never really that smart, even if they are supposed to be geniuses.
It's a function of stereotyping and shorthand. Either you have a tale "against evil" or you have a tale of "finding evil." Rarely is there time for both. if the former, the antagonist must be demonstrated early and often. If the latter, the "what is evil" question is the structure of the film. Consider THE USUAL SUSPECTS.
The other thing is "evil" isn't exactly universal. In most stories, "evil" is "evil to YOU." Very few people aren't heroes in their own minds; that includes Pol Pot, Hitler, Genghis Khan, you name it. In order to understand the true power of righteousness one need only study the evolution of religion.
I don't know that I've ever encountered a truly evil person in my life, though I have run into people doing really, really ugly things, generally triggered by some kind of emotional event, but from what I've read about serial killers, they generally seem to be very charismatic and very intelligent people who are quite capable in a number of ways.
I have encountered true, unadulterated evil exactly once, and I count among my high school acquaintances two murderers. By the time I knew how evil the guy was, he was out the door… and all I can point to as way as an indicator is a vaguely uncalibrated sense of right and wrong.
I know that sociopaths are often characterized as incapable of feeling emotion and yet, charisma functions largely on empathy.
We were sitting down to dinner with two friends. She went to school with my wife; he fell in love with her in the Navy. She had a drink or two and started bitching about psychiatry and how they knew nothing; after all, two different shrinks had accused her of "sociopathic tendencies" so what did they know and in our heads
and it all made sense.
It's not that she didn't feel emotion. It's not that she didn't have empathy. It's just that it didn't affect her. Her emotions were primarily about her and her empathy was in terms of her. Stephen King described a sociopath in It in a very memorable way; there's a kid that just doesn't believe anyone else in the world is real.
She was a lot like that. It's not that we were all there for her entertainment, it's that we just didn't count.