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My Sister's Boyfriend

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Laura hardly pauses long enough to say, “Oh right. Derek, Stiles.”

Derek turns and freezes. Stiles is—There’s nothing about him that Derek doesn’t want to put his mouth on. “Hey,” he says, croaky, weak. He clears his throat, ears burning red. “How do you know Laura?”

Laura rolls her eyes. “He’s only the boyfriend I’ve been talking to you about for the last month.”

Derek’s stomach drops. Boyfriend?

Stiles grins and his mouth is wide, mobile. “Whoa, you’ve been talking behind my back. Not sure how I feel about that.”

Laura’s answering grin is shark-like. “I’d feel very unsafe.”

“Well now I do,” he says uneasily but he’s still grinning and he’s painfully attractive.

Derek says around the ache of his heart trying to squeeze itself into a raisin, “It was nice meeting you, Stiles.”

He tries to avoid Stiles. Only he’s one of those people you want to be around all the time. He’s funny and kind and his nose wrinkles when he laughs and Derek is falling stupidly in love with him.

Laura corners him and says, “Do you like him? Tell me you like him.”

I do. Too much. “I like him.”

Laura frowns. “Just not for me?”

“I didn’t say that.” But it’s true.

Stiles finds him, traps him, when they’re both home for Christmas break. “Derek. Hey.” He’s been drinking. “So. You’ve been avoiding me.”

Derek can’t look at him. He’s too much. “I haven’t.”

Stiles smiles but it looks forced. “You did literally turn around and walk the other way when you saw me coming.” Derek cringes. “Which sucks because I thought we were getting along. Laura was pretty amazed by it. She said you don't open up to many people.” Derek flinches harder at the mention of Laura. Stiles leans into his space, concern in every line of his face. "Derek?"

“You should go,” Derek says gruffly. Stiles slides a warm hand over his shoulder and Derek wants to cry. He presses his cheek to the buzz of Stiles’s hair, turns so his lips are skimming it and says helplessly, “Stiles, you have to go. I want things I—”

He sees when the penny drops for Stiles, behind the wideness of his eyes and the heat of his gaze and he wants this too. Somehow that only makes things worse.

Derek hears the creak of his door and he can see Stiles carefully closing it behind him from the hall light.

He sits up, heart pounding. “Stiles? What are you—”

Derek can barely make out his face in the illumination from his alarm clock. It paints his skin an otherworldly blue, like he’s looking at him underwater. He kneels on Derek’s bed, his knee resting by his hip and he says desperately, “I won’t touch you. I’ll just—” Stiles licks his lips, tone dripping with disbelief, “You’re hard.”

Derek’s heart is beating wildly and he puts his hand on Stiles’s knee to stop him getting any further. “Don’t. She’s my sister. Stiles—”

Stiles shakes his head, promises, “I won’t touch you. I just want to see.” He pulls his shirt off over his head, unbuttons his jeans. He’s not wearing anything underneath. “I won’t touch you,” and it’s like a mantra. “Please,” he says.

Derek pulls down the covers, pushes down his boxers, all the while staring up at Stiles as Stiles drinks him in with a whimper. Stiles climbs on top of him, straddles him, leans back. Derek watches him slide two fingers inside himself while his cock throbs to replace them.

Stiles babbles while he fucks himself, like he can’t control himself. “I think about it all the time. You inside me, fucking me.” His thighs rest over Derek’s and Derek can feel the heat of him, the push-pull of his body as he finger fucks himself. Stiles gasps, “I’ve never wanted anyone the way I want you.”

And it’s too much. Derek is shaking with the effort of staying still and he grabs Stiles’s thighs hard and grits out while tears well in his eyes, “You have to go.”

Stiles bites his lip and pleads, “Derek, I won’t—”

Derek grabs him by the back of his neck, pulls him forward and kisses him like he never means to stop. “I will,” he says, voice wrecked with emotion. “I will.”

Stiles breaks up with Laura. He transfers from Berkeley. He doesn't speak to Derek again. No matter how many times Derek begs him to.