Stiles' hands press against the brick, palms flat. A bead of sweat paints a trail down the side of his neck, another tickles the back of his knee before sliding off and soaking into the mattress. He forces himself to breathe in, slow, out again, but there's an audible shudder he can't stop.
"You're okay," Derek whispers into his ear, breath warm and moist. Derek is behind him, as motionless as Stiles himself, one hand gripping the duct above the bed, the other pressing against Stiles' belly. Their skin is slick with sweat where they touch.
"What do you want, Stiles?" Derek demanded, looking up from the papers and books spread out on the table.
Stiles watched his feet as he picked his way down the steps. "Yeah. Um. Hey, Derek. I was wondering if you would do me a favor?"
"Could've warned me," Stiles forces out between breaths. He's gotta keep breathing, because if he panics now, there's no getting away from it.
"I didn't know this was going to happen." Derek holds him tight and close to his body. "It's never happened before. I had no reason to think it would."
"So what's different? Is it me?" Stiles says, and his voice rises in pitch. He cuts himself off, forces himself to breathe again, but it's getting harder.
"Stiles," Derek gasps, and his body rocks. "Fuck. You've gotta stop. The more you move—"
"I'm not moving," Stiles insists.
"You're getting tighter." Derek's forehead drops onto the back of Stiles' neck. "God."
"I can't help it." Stiles tries to relax, closing his eyes, urging his body to stop clenching around Derek's freakish werewolf dick but it's not working. "I can't do it. Fuck, I can't. Derek, get it out, you said you'd stop, you've gotta stop, get it out of me, please." Stiles' hands slip on the wall as he tries to get away, as he fights the grip Derek has on him. The overwhelming fullness tugs, making his eyes water and his body clench up even harder against what's inside him.
"Something bad is going to happen to me." Stiles sat on his hands to keep them still. "I can feel it. I'm next. Any moment I could get taken and my throat slashed open and then everyone will feel bad because everyone said no and no one believed me."
A tiny crease appeared between Derek's eyebrows. "So why are you asking me?"
Stiles' jaw dropped, a hand came loose and he jerked it back, gripping the edge of Derek's couch hard enough that the weave of the upholstery shifted between his fingers. "Because everyone else said no, and no one else believes me." He spoke very slow, as if Derek was a child he was trying to make understand. "Also, I figure you've got pretty low standards. Kate Argent?" He twirled his finger beside his ear and lifted an eyebrow. "Hot, yeah, but complete nut job ."
Derek wraps his other arm around Stiles' chest and pulls him back off the wall. "If I try to pull out I'll tear you apart," he says, his voice even, but with a thread of anxiety running through that chills Stiles to the bone. He drops kisses onto the back of Stiles' neck, down the line of his shoulder, humming softly and making shushing noises. "You can do this, Stiles. I know you can. You're gonna be okay."
"No," Stiles whimpers, but he makes himself stop fighting, lets his weight fall into Derek's arms, and onto Derek's lap. Immediately the pressure eases, as Derek sinks deeper, pushing the thickest part of the knot away from where Stiles is tightest. "Thank god," he sighs when he's able to breathe again, when his arms and legs stop aching from holding himself up.
"Huh," Derek says. "Should have done that before."
"Right." Stiles' eyes flick toward his phone where it sits on top of the pile of clothes on the floor, too far away to reach. "How long's it been?"
"I dunno. Maybe fifteen minutes. We just have to wait. You're doing good, Stiles. It's gonna be fine."
Stiles nods, and feels himself sinking further down. It's not hurting anymore, and he just feels full. Coupled with Derek's arms wrapped around him, it's almost comforting. Also, the knot is touching a place inside that makes him breathe just a little bit quicker. "So, why now? What's wrong with me? Is it because I'm a dude?"
Derek shakes his head, brushing his lips from side to side over Stiles' shoulder. "That doesn't make any sense."
Stiles stops. "Well, is it... Is it because I've never done this before?" He turns his head, looks over his shoulder. "Have you ever done it with a virgin before?"
Derek clears his throat. "No." He lifts his head. "I don't know. It's possible."
Stiles gives a non-verbal grunt of anger. "I come to you for a favor, to help me get rid of something that's endangering my life, and in return, you endanger my life?" He tenses up again and the knot presses harder against his prostate. He involuntarily pushes down on it. "Fuck," he gasps. "That actually felt good."
Derek's arms tighten. "You're not in danger if you don't panic. We've just gotta... God, Stiles."
Stiles is getting hard again, his dick slowly filling. He's been soft since Derek got inside him, too nervous to really enjoy himself long before the knot started swelling. It's different now, and he doesn't know why but he doesn't much care, either, because—holy crap—it feels good. "That's just unfair. Why would it only happen with people who've never had sex before?" He risks rising up, just a fraction, on his knees, sinking down again, and he whimpers. "It's not like you're not already nervous as hell, you know." He moans as he moves again. "Magic inflatable cock pretty much sure to freak you out completely."
Derek starts to help, holding Stiles by the waist, pushing up into him. "Maybe, maybe it's to stop us breeding with another werewolf's mate. Or... I don't know. Fuck, Stiles, I don't care, just keep doing it."
"Breeding?" Stiles' cock is hard and leaking on his thigh, and he reaches for it, giving it a clumsy stroke. "Pretty sure I'm not going to be any good for breeding, just so you know." He gets a rhythm going, jerking himself slow, because he's not in any hurry and it feels amazing, and he doesn't want it to end. "You'd think your dick would know the difference."
"Apparently not." Derek moves, wrapping his arm around Stiles again and easing him forward. "I feel like I could..." With Stiles bent over, holding himself up with one hand as he strips his cock with the other, Derek grasps Stiles' hips and rocks against him. "You've gotta come, Stiles, fuck." He lowers himself over Stiles' back, splays his palms over Stiles' chest and holds him close as he jerks his hips in tiny thrusts. "I'm gonna come," he whispers against Stiles' shoulder.
Stiles shudders, so close, heat building in his spine, sparking out with every brush of the knot over his prostate. "What? Again? You already... Oh my god, Derek."
Derek starts to shake all over, like he did right before he came the first time, when the knot started growing. "Gonna fill you up, Stiles, fill your belly, knot you until it takes." He gasps, moans, buries his face in the back of Stiles' neck, lips sliding on sweat, and his next words are muffled. "Gonna make you mine."
"Oh my god," Stiles groans, eyes wide and staring at the wall, both horrified and aroused at Derek's words. "You better be kidding... Oh, fuck." He can feel it, the pulsing of the knot as Derek starts to come, feeling fuller and warmer and slicker inside. His own orgasm builds like a rolling wave and then crashes over him, blinding, deafening, disorienting.
"Relax, Stiles," Derek said. "This'll be easier if you relax."
"You were gonna kiss me," Stiles accused.
"You want to have sex with me, but not kiss me?" Derek pulled back, his eyebrows drawn together into a frown.
"No, it just..." Stiles pushed himself up, reached out for Derek's hand. "I didn't think you'd want to."
Derek went perfectly still, his eyes scrunching a little. "I'm not gonna hurt you." He shifted, rising up on his knees, and he pushed Stiles down onto his back. "But I'll hold you down if I have to." His hands clamped around Stiles wrists, and he pinned them to the mattress above Stiles' head. "Because I'm going to kiss you."
When Stiles opens his eyes he's lying on his side, Derek behind him, and they're still locked together. "Um. That was a little weird," Stiles says. "Wasn't it?"
Derek clears his throat. "Yeah. Sorry."
Stiles figures Derek's probably relieved he doesn't have to look Stiles in the eye. "That's not, um. It's not actually possible, is it?"
"I've never heard of it," Derek says, and then changes the subject. "Look, Stiles, about what we just did—"
Stiles snorts. "You've never heard of half the things we've seen in the last year." He pushes the thought aside, focuses on what's real. "You did me a favor. Devirginized me and saved me from the threat of human sacrifice. So I'm just gonna stay perfectly still and wait for your...thing...to go down and I'll be out of your hair."
Derek exhales like he's been holding his breath. "That would be best." It doesn't stop him from stroking his hand down Stiles' side, over his hip, resting a hand on his thigh. "You should probably try to sleep."
Grateful, Stiles closes his eyes, still feeling the weight of Derek inside him.
Stiles lifted his head. Derek was back on the floor, and as Stiles watched, he pulled his shirt off over his head and dropped it. "Oh. Oh that's nice." He pushed himself up onto his elbows to watch.
Derek's smile was almost coy. "I had no idea you were even moderately attracted to me, Stiles." He unbuckled his belt.
"Are you kidding?" Stiles pushed himself up into a sitting position. "Cheese would find you attractive. You're probably just so used to the scent of 'attracted' from like, everyone you meet, that you think it's normal." He tilted his head to the side as Derek dropped his jeans. "Holy crap."
Derek followed Stiles' gaze, looking down at his own erect cock. He cleared his throat.
"Wow, dude. Impressive." Stiles looked up at Derek's face, determined not to stare, but he couldn't help one last glance downward. "I think my whole body just clenched."
Derek stared back, a challenge in his expression, and he wrapped his hand around his dick and gave it a stroke.
"You know, I think I have something that might fit you," Stiles babbled, just to fill the silence. "Speaking of which, do we need a condom? Cos I don't know if the werewolf thing means we don't, or—"
"We don't," Derek said. "We can if you like, but, take it from me. It feels a whole lot better without."