If it works for clothes, it works for fiction: a little mystery, a bit of a sense of “I wonder what’s under there …” is infinitely more interesting.
I learned the value of this by reading Dostoevsky. At least in the old Constance Garnett translations I used to find in the library, Dostoevsky was always putting in the phrase “for some reason.” For example, “And Rogozhin himself for some reason talked readily to the prince, though indeed his need of conversation seemed rather physical than mental, arising more from preoccupation than frankness, from agitation and excitement, for the sake of looking at someone and exercising his tongue.” (The Idiot)
Of course, Dostoevsky knew what this reason was. And I knew (or at least suspected) that he knew it, too. But his genius was to call your attention to the hidden psychological motives of his characters–motives the characters themselves might not fully grasp, or motives they might be unwilling to acknowledge, at least in polite society.
And this, to me, was both incredibly true to life (don’t we all have these secret motives, after all?) and also fascinating for the reader. I liked wondering what was hidden “under there,” beneath the blustering speeches or the flashing eyes or the blushing cheek. What hidden knowledge or secret motive lurked there? The actions of the characters, and their speeches and flashing eyes (and other “tells”), would leave a breadcrumb trail for me to follow as I read.
Here’s another example: “His secret motive for it [the duel], that is, his almost morbid hatred of Stavrogin for the insult to his family four years before, he was for some reason ashamed to confess.” (The Possessed)
Here you get a nice instance of social convention dictating (through the unnamed reason) an otherwise puzzling behavior. That’s the other side of the coin, in Dostoevsky: people behave in unconscious obedience to their own deeper desires, and (at other moments, or perhaps at the same moment) in unwitting obedience to the dictates of polite society. These raw, unprocessed underthings, which we glimpse at the slip of the fabric of the story (“for some reason”), give the characters depth and believability. Yes, and also they give the novels a kind of deeper register. We see human desire and human society in a struggle, read on the face of the actors in the story.
Most of this happens at what I’d call a subterranean level. Sometimes it comes to the surface but, to return to the clothing metaphor, its customary place is beneath, out of sight. Paradoxically, the novels succeed in revealing these hidden dimensions by keeping them mostly cloaked. They come as flashes of insight because they’re mostly hidden, mostly kept under wraps.
I don’t mean this as a call for direct imitation. Dostoevsky had his own interests as a novelist and thinker. But you don’t have to pursue his interest in psychological revelation to use this insight: that hidden, unstated things, suggested by the contours of whatever hides them, are compelling and full of profound interest.