That "misty" idea is really coming out of the mist now. I had to turn the light on in the middle of the night and write notes to myself, which I never do, because the pitch/back cover copy for it came to me, word for word, and it was too perfect to let slip. So now I know what this book is actually about -- what the main plot conflict is. Lots of details are still missing and I have tons of research to do, but I'm making progress.
I dug out my college acting textbook last week because I like exploring other things that might help in my writing and something struck me that I'd just noticed in a book I was revising -- talking (and thinking) heads don't occur in nature.
In TV news, a talking head is either just the anchor reading the story or the clip of the person being interviewed. Talking heads are dull because there's no real action. We're not seeing anything but a face. They're just as deadly in fiction, and they occur when you have long scenes of just dialogue or long internal monologues.
If you think about the way actual conversations occur, you'll notice that even in the most intense conversations, you seldom have two people just sitting and talking to each other, and even in those conversations, there's still other action going on. People make and break eye contact, shift their weight in their chairs, cross and uncross their legs, move their hands, scratch their noses, etc. The movements will change depending on the intensity of the conversation and the setting. People interact with their environments as much as they interact with each other. They may react to cold or heat, do business related to the setting and circumstances (like eating/drinking in a restaurant, doing kitchen tasks in a kitchen, examining items while shopping), or be distracted by other things happening in the setting.
It's with all these little actions that you can add subtext to the conversation. A lot of the time, we don't say what we really mean, and actions really do speak louder than words. When the words and the body language conflict, we believe the body language. If the people in the conversation like each other but don't want to admit it, their conversation may be neutral or even antagonistic while their body language shows their interest -- self-grooming behaviors (playing with hair, straightening clothes), angling their bodies toward each other, mirroring each other's movements. Or the reverse, they could be talking like they're totally civil while showing antagonism physically -- stiff posture, keeping a distance, angry facial expressions. You'd lose those nuances if you just had talking heads.
Internal monologue, or thinking heads, is even more potentially dull in a novel. That's the pages and pages of thinking. Unless we're meditating, very few of us just sit and think. We also don't plan to think or go into a room just to think. The thinking occurs while we're doing something else, and it's often triggered by something we see or hear. We go into a room to do something, see something that sparks a thought, and the thinking goes on while we continue to do whatever we were doing. The actions may then reflect the thoughts -- we may scrub more vigorously at the dishes while thinking of something that bothers us, or the thought may sidetrack us so that we forget what we were doing and do something else.
You can come up with all these bits of business by paying attention to things you do when you're talking or thinking and by observing others. When it comes to writing, pick specific actions that are meaningful and that reflect the character. You want just enough to avoid having a talking or thinking heads scene, not so much that the scene becomes cluttered or distracting. You can also watch films or television for action ideas because actors will choose specific, meaningful actions to go with their dialogue and avoid the "clutter" you may see in real life.