AKA My Pal the Serial Killer
Advice in writer blogs goes in cycles. Lately, I've read several posts about villains and antagonists. They come with the usual admonition: don't stereotype your villain; humanize him/her. After all, even Hitler loved his dog.
More succinctly: The Joker need not apply; Jack Torrance, come on down.
It's good advice. Notice whenever someone commits an atrocity, the neighbors say how ordinary the perpetrator was. They would NEVER have guessed. Not in a million years.
I am one of those neighbors. I dated the brother of a serial killer, last estimated body count at 60. If someone had asked me, I'd have said he was a nice, polite young man. Good looking. Smart. Thoughtful, even.
He attended the college where I worked as an administrator and stopped by my office occasionally to chat. Nothing earthshaking. Nothing sinister.
How's it going?
Read any good books?
Heard from your brother lately?
He sometimes brought me a donut and a cup of coffee. Thoughtful, right? I thought so.
When someone told me what had become of him and gave me the book about him, I learned his first attempt at poisoning was when he worked as a med tech. He brought in donuts for his co-workers, and he laced the donuts with arsenic.
Do I think he tried to poison me? No, I never had any symptoms of poisoning. He might have been testing how readily someone accepts food from a mere acquaintance. Because that's all we ever were. Acquaintances. A movie might have made our interactions into high drama/tension, but IRL they weren't. It's only in retrospect that I shiver and my skin crawls, because a very ordinary act took on a level of horror that I never imagined. It's a very human horror that has nothing to do with supernatural powers, drooling, or cackling. If I need a villain for my mystery series, I know where to find him.