There's probably no magic pill for this, but what would be some good ways to write what the characters don't see or don't know? To me, speaking more specifically in the horror/mystery/thriller genres, what we don't know is usually spookier. I think John Carpenter did this very well in the original Halloween. We know Michael Myers killed his sister at age six, and then escaped the hospital at age 21, and was essentially catatonic in between. What we don't know is why, and in some cases how. And I think the not knowing makes the whole plot scarier (this was all ruined later in sequels of course.) But this concept is challenging to write without it feeling "blank." So how do you create a sense of foreboding/dread about what is NOT readily apparent, or known at all?
I think it’s about tapping into the mind of the reader just enough to ignite their imagination and give enough fuel for them to pick it up and run wild.
Sounds like you're talking about creating suspense. In horror (or any other writing) two things you deal with are surprise and suspense. Surprise comes when the characters and readers are both unaware of something--when that thing happens the reader shares in the feelings of the character. Suspense comes about more when the reader knows something but the character does not. The reader's sense of suspense or dread is heightened as the character moves ignorantly toward what the reader knows is waiting for her. You can do this using cues in the text that the reader will identify, but the character will not. For example, in horror there are lots of conventions that readers are well aware of. If you tap into these standards (maybe 'tropes' is a good word) you can create dread in the reader because the reader will recognize it and know that it means something bad is coming even if they don't know exactly what it is. Alternatively, you can show the reader exactly what is coming by techniques such as switching POV or using an omniscient narrator. There, the reader knows exactly what is waiting for the character. The character remains ignorant. The tension/suspense/dread etc. on the part of the reader climbs as the character moves closer to whatever horrible thing awaits.
Creating suspense is certainly a part of my original question. I enjoy the buildup, little sequences of things that are going to culminate into something. But what of the explanation, or logic of said event/character? I guess I left that out of my original post. Does everything need an explanation or justification? Where is the line between what is necessary to be explained and what can be left out? Sometimes a tree is nothing more than a tree, with no further explanation needed. But other times, it might be a "special" tree...but I may not want to explain all of that if I'm concerned about tying up the plot ends too cleanly - if that makes sense?
I suppose this varies reader by reader. I tend to find things more disturbing if the author errs on the side of explaining less and just gives small pieces about what is happening. As @Cilogical notes, you're never going to replicate an individual reader's imagination about the sort of things that scare them most. If you give them just enough to let their own imagination do the rest of the work for you, I think you end up with a better result. There is writing advice that says "resist the urge to explain." I think that's generally good advice. If a reader needs to know something in order to understand the story, give it to them in one way or another. But if you're trying to create dread or apprehension I think less explanation is better than more.
Haven't read all the responses, so apologize if this has already been said, but I might have characters discuss their own theories about the mysterious events/goings-on. It emphasizes that they don't know, and also can suggest possibilities to the reader. Or if only the main character is present, you might give him/her an inner monologue or dialogue about what might be going on.
I agree @Steerpike that the 'less is more' approach is better for creating a tense atmosphere. I just feel sometimes I struggle trying to convey the unknown elements in an appropriately unsettling way. Trial and error I suppose... Also @Xoic has a great suggestion of creating dialogue between the characters, or thoughts of the MC, about what might be happening.
I don't know what a writer is, but when I see one I somehow recognize him. Horror films do rely heavily on music. The Shinning wouldn't work with a soundtrack from The Sound Of Music. Mind your soundtrack.
