Ancient Greek playwrights had a simple way to get themselves out of any corner they’d written themselves into: some god, even more bored than usual with immortality, would kill a few minutes by intervening in the mortal drama below. (I have an impression of the gods acting like twelve-year-old buys with a magnifying glass, watching an anthill, wondering what catastrophe they can think up next.) God in the machine (Deus en machina) is largely discredited today as a fictional device.
Humans haven’t changed all that much since sapiens became our last name. We’re taller, better groomed, and less prone to be killed and eaten by the same creature we hoped to kill and eat ourselves. Aside from that, most changes to human life have been technological, not evolutionary. Fire, the wheel, sliced bread. Stuff like that. Modern writers still need a way to get out of self-inflicted traps. I’m too middlebrow to say how literary writers do it (assuming they have any story in their book at all), but I know what’s popular with mystery writers:
Not sure now to explain the villain’s motivations? Make him a serial killer. Serial killers are by definition broken, so you don’t really have to explain them. Maybe they were abused as children. Maybe not. Maybe they’re just fucked up. Doesn’t matter. No one really understands what makes a serial killer; they have some things in common, but nothing definitive. True, there’s the triad of things shrinks look for after the fact: bed wetting, setting fires, and animal abuse, but even all three of those don’t always mean someone will become a serial killer.
I recently read an acclaimed book that, while I didn’t care much for it, had many admirable aspects. The author wrapped me up in an improbable situation until I really wanted to see how he resolved it. Then he dumped it all on a serial killer who preyed on women and then committed suicide, which allowed to evade writing about what came after the heroes figured out who it was, which can be as involved as the actual detection. It was a huge letdown, and I think it colored my acceptance—or lack thereof—of the rest of the book..
Serial killers are a cheat. They typically prey on women (they’re nuts, not stupid; a man might kick their ass), which is another trick to add suspense, as danger to women is tried and true way to add some cheap thrills to a suspense story.
There have probably been more fictional serial killers created in the last thirty years than have existed in all of human history, if we distinguish serial killers from people who just happen to kill a lot. What is the fascination? Why are writers—and, apparently, readers—drawn to them? They’re the most formulaic element in the formula for a “breakout” novel: they raise the stakes. Place the hero, or someone close to the hero, in ever mounting jeopardy. How many more trees have to die before people get tired of being jerked around like this?