When I asked my doctor how much blood loss results from stabbing a demon with a steak knife, I got an answer. (It was only after I repeated the story that someone asked how she knew that. Hmm.)
I once called a few official sources to inquire about gun laws in their county where demons exist. I approached them seriously, identified myself as a novelist and politely asked for their time to answer one question. I also made sure I didn’t call during a four-day week (when work is piled up) or at the end of the day when they’d like to wrap up and go home. I’ve been happy with the answers and gratified that twice I was able to make them laugh.
(In rereading the above, I realize I should clarify that as far as I know, there is no county where demons exist. Just sayin’.)
Worldbuilding is an important aspect of a fantasy novel. If our rules make sense, the reader will accept them. In urban fantasy, most of the rules for building a believable world are already in place. In my novel, it’s still illegal to make a left turn on a red light. And pizza needs oregano. (Okay, not for everyone. I’m not a militant on that. Just pass me the oregano for my slice and we’re fine.)
I’ve read dozens of vampire stories set on this planet where the rules for vampires change. Some never eat. Some do. Some can go out in daylight, others can cross water, and a few even cook with garlic. How do all these contradictions work?
It’s simple. Inside those finite pages of a story is a world that writers make logical. We set up the rules and the reader accepts and (hopefully) enjoys them. Presenting the normal along with the fantastic is what makes it work. It’s one of the reasons why urban fantasy is my genre of choice. I know how things work in New York City and what I don’t know, I can find out. If I want to add a demon or ghost to the mix, the rules and regulations for us humans are already in place. (Apologies to any nonhumans reading this.)
But the rule remains: The setting has to make sense. When I read, I want to immerse myself in that world. I will accept that bananas grow in midtown Manhattan in the winter if it’s been set up properly. If the sky in the Bronx turns from blue to red-and-green stripes with no warning and no explanation later, I’m going to put the book down.
Research. Make sure you aren’t defying the law of gravity without a good reason and that the reader understands it. Getting the information I needed on demon stabbing helped me to write a better scene. A more believable scene. Although, yes, now I’m wondering how my doctor knew that….