“Why didn’t you tell me mates were a thing?”
Stiles watches Derek roll his eyes at Scott’s question as he continues to sift through the debris in what used to be the kitchen of the burnt out Hale house.
What’s he looking for? Bones? Stiles can’t imagine what else he might be expecting to find. He tries not to shiver or look too closely at what he might be standing on.
“Because you don’t have one,” Derek answers flatly when he realises speaking will get them to leave quicker than silence.
“Why not?” Scott asks, indignant.
“You’re not a born werewolf.”
Scott cocks his head. “That doesn’t sound fair.”
“You’d rather your choice was taken away?” Derek snaps, looking up at Scott for the first time since they arrived.
“Why, aren’t you satisfied with yours?” Stiles crows.
All Derek does is scowl at him.
But after that, Stiles can’t stop thinking about who Derek’s mate could be. He hadn’t denied that he’d already found them, and for a moment, Stiles entertains the idea of it being Finstock, the real reason Derek came back to town. He sniggers for a good few minutes about that.
When he’s done, he rolls onto his back and blinks up at the ceiling through the darkness.
Derek had said there was a pull to be with them, to protect them, so Stiles must have seen him with them at some point. But the only person he can think of is that one time he spotted Derek paying for gas and giving the woman behind the counter a very nearly almost smile. Other than that, he’s always showing up at the school being a creeper watching Scott, and Stiles can’t decide if that’s more shudder-worthy than the Finstock theory.
If a mate is supposed to be a born werewolf’s other half, there must be a reason the thought of them gives him such a sour look, beyond having no ability to choose. Like always pushing his buttons. Or being an embarrassment. Or underage. And maybe with a relative in law enforcement.
Stiles lifts his head off the pillow and stares wide-eyed into the darkness. But only for a second before he drops back down with a snort.
There's absolutely no way.
Except, now the thought has crossed his mind and been discarded, there's a strange weight pushing down on his chest.
He pictures Derek tossing and turning in that derelict house in the woods, all walls and no roof, alone but surrounded by ghosts.
The weight begins to ache and he flips over, burying his face in his pillow with a groan. He’d wanted to make a discovery about Derek, not himself! That’s what he gets for sticking his nose where it doesn’t belong.
Or maybe does belong?
He pulls the covers over his head. It’s going to be a long night.
After that, he can't stop reading into everything. Like why Derek climbs in through his window when he needs help instead of going to Scott, or when research needs to be done instead of going to Deaton. Stiles knows Scott’s not much better than a puppy and the vet's cryptic as all get out, but surely that's better than the fragile human teenager who has no idea what he's doing?
And why does Derek start catching a ride with him when shit goes down instead of taking his own? Stiles doesn't argue and tells himself it's because Derek was willing to rip his throat out with his teeth when half-dead on wolfsbane, so at full strength he’d have no chance of survival. Not because he kind of likes being in a private, enclosed space with him.
One night, when Stiles is dropping Derek off at the Hale house after another close run-in with Kate Argent and her pesky wolfsbane bullets, he can’t contain his curiosity any longer.
“Hey,” Stiles says and Derek pauses with one hand on the car door handle, turning back to look at him with impatient eyebrows. Stiles has never really been one for mincing words, and he doesn’t start now. “Am I your mate?”
Derek stares at him, a brief parting of his lips the only sign he was caught off-guard, and when he finally speaks it’s accompanied by a low warning growl. “Go home, Stiles.”
The door slams shut and Derek disappears into the darkness using that werewolf-y trick of his, the one he still hasn’t taught to Scott.
Stiles sits back in his seat, realising he’s breathing hard, heart hammering in his chest.
But Derek didn’t answer and he can’t let it go.
He stumbles out of the car and up to the dilapidated Hale house, ignoring Derek’s bellow of “ I SAID GO HOME! ” echoing from somewhere inside - or outside, depending on the state of the roof wherever it is he’s standing.
He opens the front door to find Derek in the entryway, feet planted and arms crossed, glare verging on murderous - though it’s hardly the first time Stiles has been on the receiving end of the expression.
“You didn’t answer my question,” he accuses, planting his own feet despite knowing it will do nothing to anchor him if Derek decides to physically remove him.
Derek snarls, eyes flashing blue and fangs coming out to play, but he’s trembling, like he’s barely in control of it.
Stiles may be stubborn, but he doesn’t want to die, so he tries to back away, but Derek jerks in what he’s sure is an aborted pounce. He stills, realising, somehow, that it’s not an attack coiling Derek’s muscles.
“Get out,” he grits through his fangs. “Get out before I-”
“What? Rip my throat out?” Stiles challenges. Slowly, hesitantly, not sure what’s even driving him to do it, he tilts his head back and bares his throat.
Derek’s eyes flare even brighter as they widen and there’s a high-pitched whine before he seems to go slack, sagging forward until his face collides with the side of Stiles’ neck. He sways under the weight, shivering at the flutter of Derek's eyelashes against his skin.
“Come on, big guy,” he grunts. “Let's get you sat down.”
He manages to shuffle Derek back a few steps to what used to be the lounge doorway, but halts when he catches sight of what's left of the sofa, covered in ash and- well, Stiles doesn’t even want to know. “On second thought, back to the Jeep. You can’t stay here.”
Derek’s grip tightens and Stiles soothes a hand over his back.
“You can’t stay here, Derek,” he repeats, gently, speaking into his hair. “Not anymore. I won’t let you.”
The tension that had returned to Derek's shoulders loosens once more and Stiles coaxes him outside into the fresh air with no more fuss. It's only when he's gotten him in the car - finally seeing his wide, innocent eyes when they're forced to part, the ghost of the boy who lost so much - that he realises his plan has more than a few holes. But he knows his dad has the same drive to do what's right as he does and it will take just one look at Derek's vulnerable shell to crumble and agree to offer up their spare room.
And if Derek is too skittish to part from him and Stiles allows him to spend the night in his room - as the hand he curls around Stiles’ wrist as soon as he climbs in the driver's seat tells him - well, that's something his dad never needs to find out.