The other night, while my baby was hollering at 4 a.m. (we think he had a nightmare, and we soothed him and changed him and so on, but after a while we just had to let him cry himself back to sleep), I was laying in a semi-awake state, thinking about the difference between horror stories and fantasy stories.
Specifically I was thinking about a story involving a magical door, a scary door through which potentially scary things might emerge into our ordinary world, and trying to think of a good way to end such a story. It seemed to me, in my trancelike state, that the moment in which the doorknob on the scary door began to rattle — the moment when something on the other side was on the cusp of emerging, with the mortals on this side watching in wide-eyed dread — would be a good place to end.
And, for a horror story, it wouldn’t be a bad ending. Much horror is rooted in the unknown. When you can see the monster, it’s almost always a let-down; the unseen monster, the monster implied, is far more frightening than the monster revealed.
But the next morning I found the notion of ending the story there a bit disappointing, perhaps even a bit craven. After all, the real leap of imagination would necessarily come when the door did open, and I had to create something on the other side worthy of the build-up, worthy of that sense of dread.
It seemed to me that, at that point, it would almost have to cease being a horror story, because I would need to explicate, explore, reveal — and have my characters somehow process and engage with whatever they saw. At that point, the central evocation of fear would be pushed aside in favor of other effects, and it would cease to be a horror story (in the sense of a story designed to invoke horror in the reader). Both horror and fantasy are rooted in the consideration of Mystery, but they approach that Mystery in different ways.
I was reminded of one of the widely-agreed-upon differences between a technothriller and a science fiction novel: in a technothriller, the status quo is restored at the end, while at the end of a SF novel, the world is changed.
And so my idea for a very short horror story turned into an idea for a rather longer fantasy story — albeit one retaining elements of horror, and several horrific moments; but not engineered for a horrific end.