Part 1 of the Ruined series.

Derek can't be the only one who's noticed how Stiles has changed. There's the faint scent of old blood and slow healing. The sharpness of alcohol that seeps out of his pores. Chemicals in his blood that weren't there before.

They see him every day. They should know he needs help, but Derek's seen Stiles paste a fake smile on his face and bullshit his friends, and they're all too busy with their own pain that they can't see it for what it is.

He corners Stiles as his friends leave the loft. Pushes him against the closed door, doesn't need force because Stiles is a shell of his former self and doesn't put up a fight. There's dark shadows beneath his eyes that look like bruises, and there are hollows under his cheekbones that tell Derek he's barely eating enough to keep him alive.

Yet there's beauty there, in the neglect and ruin, there's a poetry to Stiles' coping mechanisms. Physical pain to counterpoint that buried so deep it can never be extracted. Prescription drugs washed down with his father's whiskey to dull his mind. Silence and lies, swallowed so easily, because they're hurting too.

Stiles blinks at Derek in surprise, and his eyes are still the same, too big for his face, dark and liquid and full of emotion. "What," he says, and it's not even a question.

Derek traces the black circle beneath Stiles' eye with his thumb. "No more," he says. He grabs Stiles by the wrist, pushes up the long sleeve to expose crosshatch scars on the soft, pale, inner skin of his forearms.

Stiles tenses, tries to shove Derek away. "You've got no idea how it feels, Derek. I can't sleep—"

"I know what helplessness feels like, Stiles. I know what it looks like. I accepted a long time ago that there are things I can't change. You've got to do that, too."

Stiles blinks and then snorts. "Are you seriously 12-stepping me? You?" He twists out of Derek's grip, reaches for the door. "Keep your intervention, Derek. I'm fine."

"If you want to hurt, I'll do it," Derek says, putting his hand on the door so it can't be opened. "You want oblivion? I can give you that. I'll make it so you can't think. I'll make it so you can sleep again."

Stiles stops, frozen, hand still on the door. "How," he says. "How are you gonna do it?"

There's an instant where Derek wonders at the wisdom of it, whether he's taking advantage of a vulnerable kid. But Stiles will end up dead if he carries on, either through carelessness, or intent.

So he flips him around, gets his hand around Stiles' throat, tips his head back and pushes a thumb against his windpipe with just enough pressure to make Stiles rasp with every breath, to taint his scent with the flavor of pain. "Like this," Derek hisses softly into Stiles' ear. With his free hand he tugs open Stiles' jeans, gets his fingers around the cock that's already hard and removes at least one question from his mind.

Derek jerks Stiles off in quick strokes, swallows his shallow gasps, chokes him until he goes red in the face.

Stiles clings tight with both hands to Derek's wrist, but never tries to push him away. He couldn't, but if he tried, Derek would stop. Derek doesn't know if Stiles doesn't care if he lives or dies, or if he trusts Derek not to kill him.

Right now it doesn't matter.

All that matters is the peace that settles over Stiles' face, all that matters is that the haunted look fades, at least for these few moments. And when Stiles comes in Derek's hand and his knees go out from under him, Derek catches him, takes him to bed, strips him bare, exposes and catalogs and kisses every scar, every bruise, every sharp angle.

Hours later, after Derek has taken him apart from the inside, blocked all thought, all speech, reduced him to physical sensation alone, Stiles is still asleep.

Derek lies awake, admiring a different kind of ruin.