It hits Derek like a sack of bricks, the exact instant he realizes how fucking in love he is with Stiles. Maybe he’ll look back on this at the end of his life—whenever that happens to be—and remember the moment perfectly, and maybe he won’t; waking up slowly in bed to the soft postdawn light of his bedroom, seeing Stiles so gorgeously silhouetted by the curtained window, dressed in nothing but his underwear and cradling a mug of hot coffee, one leg casually bent, posture so painfully relaxed and innocent of Derek’s gaze. The sight overwhelms Derek in a heartbeat, drowns him in its weight, but if his love is an ocean he’ll never wish for a breath of air again.
All Derek can see is the dark, fuzzy impression of the back of Stiles’s head as he looks quietly out the window at something Derek can only guess at. A private mystery that, like a lot of things, like Derek, now, belongs to Stiles and Stiles alone, that might put a lingering hint of a smile on his lips when he finally—a minute from now, an hour maybe—turns and catches Derek staring. Knowing Stiles, the smile won’t be long for a teasing smirk and some offhand remark about Derek’s creeper tendencies, and then the moment’ll be gone, replaced by flirtatiously traded barbs and maybe a lazy round of wakeup sex. But until then, this Stiles is all his, the long, brushstroke-graceful curve of his broad shoulders down to the sensual dip of his back, the tender handspan of his impossibly narrow waist, the gentle swell of his ass and long lines of his legs, the unspeakably sexy way his skintight briefs cling to his cock and balls. Even the sight of his exaggerated puppy-paw hands and feet, for once motionless and calm, catches Derek’s breath in his chest, details of the body Derek knows so intimately just barely visible against the backdrop of morning sunlight.
He must make a noise of some kind, a gentle releasing of all the things suddenly building behind his breastbone in an unbearable swell of feeling, because Stiles suddenly turns, a minute pivot of hip and shoulder, and he’s looking at Derek with the same serenity he’d reserved for whatever he was watching outside. The smile isthere, but stays quiet and knowing for a drawn-out second as they do nothing but gaze at each other from across the room, Stiles’s expression open and warm and heartbreaking as the steam from his coffee teases tendrils up his jaw that Derek wishes very badly were his fingers, his lips.
It’s almost too subtle for Derek to catch, and would be if he didn’t know Stiles’s face so very, very well, enough to notice the way his mouth and eyes soften just so, a tiny quirk of the lips Derek hopes no other living soul will ever get to see, just him. And he knows, then, that Stiles understands just what he’s thinking, can read all the same things off Derek’s expression as Derek reads in his.
For a second Stiles opens his mouth like he wants to tell him, uncaring as ever that speech isn’t always necessary as long as it makes him happy. And from the gleam of his eyes, it’s clear saying it would bring him no small joy. But then he shuts it again and shakes his head a bit with a smile and a rueful chuckle, takes a step closer and says instead, “Hey,” low and private, something for Derek and no one else.
And that’s all it takes, that right there, that one word. It’s enough; it’s all he’ll ever need to know.