You don't have to battle a demon, vampire or monster for them to have a role within a story. Sometimes they appear for another reason, their purpose merely to prove a point like scaring a character into understanding the world they've just found themselves in. In The Day of First Sun I threw Annie into the world of the non magical, similar to what she's dealt with before and yet different because she's never worked so closely with the FBI. Making things worse for Annie, is the fact she has to investigate the crime with the eyes of the world watching. She understands the ramifications of keeping her secret from the world, but what about the FBI agent who drags her into the case. He's never dealt with a magical crime before.
That's where I bring in the magical creature. Curious, Jack Ramsey finds himself in The Snake Head Letters, the all wizarding book store in which the proprietor illegally sells him a Book of Shadows, the witch or wizard's heirloom passed on from generation to generation, the book which details the experience of the witch throughout their lifetime. However, the unscrupulous shop keeper, sells a book about the darker side of magic, with fearsome creatures that open the FBI agent's eyes to a world he never knew existed.
This is Jack's true introduction into the entire magical world, exposing the worst that can be experienced and as he reads the book, he comes across the Aicha Kandida. I chose to introduce this being because in my basic research, it's a creature that singles out lonely men and Jack is just that, single and lonely, working late into the night, not even remembering the last time he found himself in the company of a woman.
The monster was perfect. A predatory water demon who appears in the form of a beautiful young woman, killing their prey by luring men to their death. The curious victim seeing the beautiful woman by the water's edge, the victim saunters over and once within reach, they are dragged into the water and consumed by the creature.
As Jack read the book searching for information pertaining to the mystical Orb of Eridu, he became engrossed by the animated picture of the beautiful woman and horrified when it changed into its true form, murdering the victim in front of him. I didn't need to bring the monster to life, it was simply an entry in The Book of Shadows, one little glimpse into the magical world and yet it shakes Jack to the core and he's forever changed by the experience.
Maybe one day I'll bring the demon to life, but only for a larger purpose. For now it will remain a distant, disturbing memory, reminding Jack to why he must keep their secret. Who would believe him anyway?
What's your most creepy monsters? Vampires, werewolves, ghosts? Mine is the Weeping Angels. Whovians know what I mean.