Folklore and Kitty
At some point, most speculative fiction writers come to the realization that nothing they can dredge from their imaginations will ever be as strange as what reality can produce. That's why, when you're trying to come up with some wild and bizarre idea, reality can be your best friend. A Filipina friend of mine passes along stories that her mother tells about manananggal, vampires who leave their legs behind to fly through the air and suck out fetuses through the navels of pregnant women. Children in the Philippines are told that if they come across legs lacking a body, they should sprinkle salt on them because that will prevent the body from returning, and destroy the vampire.
As soon as I figure out how to work it in, you can bet that's going in a story. The trouble is, no one will ever buy it. It's too weird.
On to skinwalkers. Hollywood has taken to using this as a shorthand term for "Native American werewolf." (When they don't use the term in a whacked out literal sense. I'm looking at you, Dresden Files.) This isn't technically correct, and only tangentially descriptive. The real, living folkloric source for the term skinwalker is so much more interesting. I made it my mission to not take the shortcut but to use the term the way it was meant to be used (in Kitty Takes a Holiday). First, because the shorthand pisses me off. (Why does a Native American werewolf need a special term other than werewolf?) And second because I think it makes a much more interesting, creepy story. As I said, I can't make up anything stranger than what's already out there.
The "real" skinwalker is a kind of witch, a magic user specific to Navajo culture. Very evil. These are not good people, because of what they do to get their power. Namely, they must sacrifice a family member. This is usually accomplished using a ground-up powder made from corpses that works like a poison. Once they have the power, skinwalkers can transform into any creature they wish by donning that creature's skin. This is serious death magic, and those with the slightest suspicion of being involved with it are shunned. There is still word of communities where a person could be forgiven for murder, if the murder victim is believed to be a skinwalker.
The interesting thing is trying to find anything about this firsthand. No one from this culture wants to talk about skinwalkers, because demonstrating the least bit of knowledge can bring suspicion onto you, which in turn can bring discrimination and violence. So the real interesting question becomes, what kind of person would risk it? What kind of person would want that power so much that all the sacrifice and death is worth it? It's the question that every culture asks in one form or another: what is evil?
These things--symbols, stories, magic--have meaning to their cultures. Our stories are richer if we let that meaning show through. Suddenly, they feel real, because they're taking place in a real world (someone's real world, at least) and not Hollywood. Something that happened while I was writing the second Kitty book (Kitty Goes to Washington), I realized there were no limits. Once you establish a world where vampires and werewolves are real, anything can be real. Any kind of magic, mythology, and supernatural belief is fair game. There are no limits. But to explain these things in the real world, they have to seem real, and I think that means staying true to the roots. Which is okay, because like I said--those "true" stories are pretty much creepier than anything I could come up with.