It's not just about the demon itself, but the way the horror amplifies when you layer a predatory charisma on top of a supernatural threat. An incubus character forces a confrontation with a very specific kind of dread: the violation of intimacy. Most horror monsters are external, they chase you through a house or lurk in the woods. But an incubus plot often hinges on a victim feeling drawn in, even desiring the source of their own corruption. The horror becomes internal, psychological. Is this attraction real, or is it a supernatural compulsion? That blurring of lines is where the real terror lives.
I think the best incubus stories I've read, like 'Certain Dark Things' by Silvia Moreno-Garcia, don't shy away from the bodily horror either. It's not just a seduction; it's a consumption. The victim wastes away, their vitality literally drained. That physical decay mirrors the psychological erosion. It turns a bedroom, a place of safety and vulnerability, into the most dangerous room in the house. The plot isn't just about defeating the monster; it's about the survivor reclaiming their own autonomy, their own desire, after it's been weaponized against them.