Stiles' heart beats faster than usual as he switches off the lights on the ground floor of the rebuilt Hale House. The last members of the pack have just left after their weekly get-together, which leaves just him and Derek in the building. He double-checks that the front door is locked before ascending the stairs to the first floor and walking down the hall to the master bedroom, which he and Derek have shared for just under two years now. They've been the best two years of Stiles' life.
Entering the bedroom, he finds his mate sitting on the side of the bed in just his black boxer-briefs. He feels the thrill of anticipation, his dick already half-hard.
"You're sure you're okay with this, right?" Stiles asks, just to be certain. He would, but he'd rather not have to stop once they've got things going.
Derek looks like he's resisting rolling his eyes. "I wouldn't have agreed in the first place if I had a problem with it, Stiles."
"I know, but—"
"Stiles?" Derek interrupts him, raising his thick, ever-expressive eyebrows.
Stiles blinks. "Yeah?"
"Shut up and go get yourself ready or I really will change my mind, and it'll be because you took too long."
Even though he's sure it's empty, the threat spurs Stiles into action. He darts into their en suite bathroom and shuts the door behind himself, the sound of Derek's quiet chuckling chasing him. It's a good sound. He relieves himself and then stares into the mirror above the sink. He gives his reflection a mental pep talk, telling himself that he can do this.
Stiles has been thinking about this for a long time. It took him weeks to work up the courage to talk to Derek about it because it's not like anything they've done in bed before. Since they mated a few years ago, their sex life hasn't exactly been vanilla—at least not from Stiles' human perspective—but this is different.
The fantasy came to him about a month ago, after a particularly vigorous round of lovemaking had left Derek sweaty and satisfied, the side of his face smushed into the bedding because he was too worn out to even fall down from his knees. Getting Derek into such a state had filled Stiles with pride—gangly, awkward Stiles had done that to sex-on-legs Derek Hale—but then he'd pulled his softening dick out of the werewolf's hole and seen how loose it was.
If he hadn't just orgasmed, the sight would've had Stiles raring to go again then and there. As it was, he wanted to slip his fingers inside—all of them, just to see how much further he could stretch out Derek's used hole.
Could his Sourwolf take his entire fist?
While he spooned the older man later that night, Stiles had lain awake for a while longer and pondered how the hell he could bring up something like that. He didn't come up with a good answer before drifting off himself, so he didn't say anything the morning after.
But he never forgot. While the sex he and Derek had from then on was always great, Stiles was distracted, the fantasy always in the back of his mind. He was sure that Derek wouldn't judge him, even if he didn't consent to try it, but something stopped Stiles from telling Derek until the other man finally confronted him a few days ago and got the truth out of him.
As Stiles thought would happen, the Alpha hadn't judged him, but he hadn't exactly leapt at the idea either. Stiles had been ready to tell him to just forget about it when Derek took a breath and agreed to try it.
And so tonight, Stiles is finally going to find out if the real thing measures up to the fantasy. He really hopes it does, and that Derek likes it too and will want to do it again in the future.
With one last glance at his reflection, Stiles whips off all of his clothes and comes out of the bathroom to find that Derek has moved backward to slouch against the headboard. He has his left hand resting over his flat stomach and the other tucked behind his head, the picture of calm confidence. Stiles is jealous. He himself is anything but calm. It was his idea, yes, but now that he's really about to do it, he can't get rid of the nerves that assault his system. He's alone with the love of his life in a safe environment, but it somehow feels a bit like the times he'd come face-to-face with any of the adversaries the pack has fought over the years. From the concern that appears on Derek's stupidly pretty features, he can sense it too.
"Don't tell me it's you who's getting cold feet," the werewolf says, frowning.
"No," Stiles denies. "I wanna do this."
"Then why is your heart going so fast that I can barely hear the individual beats?"
Stiles takes a deep breath and climbs onto the bed with his mate. "I don't know why, but all of a sudden I'm nervous," he reveals.
"That's natural, Stiles."
"Yes. How do you think I felt the first time I told you that I have a knot? Or when you found out how much the idea of breeding you excites the animal side of me?"
Stiles inclines his head, seeing Derek's point. "I guess."
"So…you good to go?"
"Yeah. Are you?"
Derek's mouth stretches into a smirk. "I don't know. I might need you to come up here and kiss me first. If that sounds like something you'd be interested in."
Grinning, Stiles crawls across the king-size mattress and insinuates himself between Derek's thighs. He plants his hands on the pillows on either side of Derek's ribs and brings their faces close enough together to feel the Alpha's breaths. "I think I could be convinced."
When their lips touch, it's tender for the first few seconds but quickly evolves into something much more passionate. Stiles moans when he feels Derek's fingers in his hair and kisses him even harder, tongues sliding together and teeth clacking. He's so hard, he thinks his dick could pound nails, pre-come already leaking from the slit. He lowers his body so that he can grind his erection against the front of Derek's boxers and is glad to discover that the Alpha is just as aroused as him. He rolls his hips sinfully, with a level of coordination he didn't possess a few years ago. He's had a lot of practise since getting together with Derek, though—practise that both of them enjoyed immensely.
When air becomes an issue, Stiles breaks the kiss and stares down into Derek's blood-red eyes.
"Stiles…" the werewolf murmurs, his voice low and filled with arousal.
"Get naked and turn over," Stiles commands, his tone brooking no argument as he moves away to give Derek space to get into position.
Once he has, Stiles follows the dip of the Alpha's spine with his eyes until he alights on those perfectly sculpted cheeks. Just the sight of them has him wrapping a hand around the base of his cock to stave off a premature orgasm. Derek's ass has tormented him in the best way since they first met that fateful day in the preserve, back when he could only sneak glimpses of it and imagine what it looked like underneath Derek's clothes. Now he knows.
Derek's ass is delightfully hairy, the dark hairs from his muscular thighs continuing up over the tight globes of flesh that still somehow jiggle beautifully when Stiles fucks him from behind and his hips slam into them. He can't resist getting his hands on them.
When he's sure that the danger of his orgasm has passed, Stiles moulds his hands to each cheek and squeezes. He relishes their firmness and the feel of the soft hairs against his sensitive palms. Before he moves on to the main event, Stiles spanks Derek's cheeks to watch the way they move. Derek's whole body jolts in surprise and he glares back at Stiles over his shoulder, but he isn't truly mad. Stiles just winks at him and then retrieves the lube from his bedside table.
"Deep breaths," he tells his mate as he slicks up two of his fingers.
To begin with, Stiles rubs his index finger in gentle circles around Derek's hole. Because of Derek's werewolf healing, it's so tight that it's almost like the first time every time Stiles does this. He coaxes Derek to relax, getting him used to his finger until he feels the furled muscle start to give. Then he slips his finger inside, just up to the first knuckle.
He slowly thrusts it in and out for a few moments before going deeper, to the second knuckle this time and then all the way. Derek pushes back onto the long digit after a while, which Stiles takes to mean that he's ready for a second. Stiles pulls the first out long enough to apply more lube, and then he carefully works both fingers into Derek's body, the slick heat feeling wonderful as he encases part of himself in it. He scissors his fingers apart to stretch Derek's hole and skates the pads occasionally over Derek's prostate to help him deal with any discomfort.
Finally, Stiles inserts third and fourth fingers. He's already used so much lube by this point that it matts down the dark hairs around Derek's hole and drips down his perineum to his full balls. Stiles cups them with his other hand, rubbing the lube into the wrinkled skin and tugging lightly on them because he knows Derek likes it. Sure enough, the werewolf moans loudly and arches his back, putting himself on even better display for his human lover.
When Stiles peers beneath Derek's body, he spies a stain forming on the sheets. It gets bigger and bigger as more pre-come drips copiously from Derek's cock, hard and throbbing with need. Stiles can sympathise. His own erection still demands attention, but he doesn't give it any yet. He still has work to do, so instead, he lazily thrusts his four fingers in and out of Derek's hole and marvels at how stretched out it is already—and they've still got quite a ways to go.
After a few minutes of this, Stiles starts to turn his wrist every time he pushes his fingers inside Derek's body, incrementally corkscrewing his way deeper and deeper until it gets truly difficult. He releases the Alpha's balls and pets his hip as he tries to work his knuckles past the resistance Derek's hole is putting up. Something so big isn't meant to be shoved in there, but Stiles is nothing if not persistent, and Derek hasn't asked him to stop yet.
So Stiles keeps going. He squirts even more lube onto his wrist and rubs it all around to make sure that everything as is slick as it can possibly be before he folds his thumb close to his palm and gives one last push.
And it's in.
Derek falls down onto his elbows with a loud curse as his poor hole clamps down tight around Stiles' slender wrist. He buries his face in his forearm and breathes shakily, obviously in some pain. Stiles doesn't dare to move his arm again until Derek has got used to being filled so much.
While he waits, he whispers to Derek, praising him for taking his hand so well. He tells him how proud of him he is, how grateful he is to Derek for letting him have this. He tells him how pretty he looks, his hole all stretched out around his wrist, the usually furled skin made taut as it grips Stiles. Unable to help his curiosity, he even runs a finger over the rim and is fascinated by it.
After a while, the near-nonsensical ramblings have their desired effect and Derek breathes easier again. His hole doesn't hold Stiles' wrist quite so tightly, which Stiles sees as a sign that he can move again. He goes slowly, unclenching his fist in the warm clutch of Derek's insides so that his fingers reach deeper than he has ever gone before. Derek whimpers as he does so, but when Stiles immediately stops again, he all but begs him to keep going.
"Don't stop!" Derek exclaims, spreading his legs wider. "It still hurts, but it feels so good at the same time."
"Okay," Stiles responds, more to than happy to oblige.
With a jerky nod from Derek, Stiles twists his wrist and can't believe how it feels. His entire first is actually inside his mate's body. It's even better than he could have possibly dreamed, feeling the way Derek's insides twitch and convulse around his hand with every small movement Stiles makes.
After some experimenting, he deduces that, if he turns his hand just right, the knuckle of his thumb will press against Derek's prostate and cause him to shudder and swear repeatedly. The stain on the sheets gets even bigger as a near-constant stream of fluid leaks from Derek's cock. There's so much that Stiles worries for a moment that he's actually made Derek piss himself, but the fluid is thicker than urine and doesn't smell like it either. It's just the constant prostate stimulation taking the already high amount of pre-come his Sourwolf naturally produces and dialling it up to a hundred.
"Damn, that's hot," Stiles whispers, unable to tear his gaze away.
For another few minutes, he does the same thing, pressing deliberately on Derek's prostate until a small lake of pre-come has formed beneath the Alpha, so much that it's not even soaking into the expensive fabric anymore. Stiles forces moan after moan out of Derek, so many different sounds that Derek's voice soon becomes low and gravelly. It's mixed with the occasional growl that goes right to Stiles' dick and makes him leak more pre-come too.
Eventually, Stiles tries something else. With great care, he attempts to pull his hand back out of Derek's body. Derek whines his disapproval but doesn't otherwise do anything to stop him, so Stiles keeps going, pulling back a bit and then pushing his hand forward again, back and forth so that he's effectively fucking Derek, albeit shallowly.
Stiles would like to fuck him with his fist for real though, so every time he pulls back, he goes a bit further, Derek's hole stretching wide all over again as it's forced to release more and more of Stiles' hand. The noises the Alpha makes change back into what they were before, from disapproval to vehement approval as he moves with Stiles. He rocks forward on his knees every time Stiles pulls his arm back, until Stiles' hand finally leaves his body with a pop.
Stiles' mouth hangs open when he gets an eyeful of Derek's hole. It can't seem to close on its own anymore, gaping just like Stiles' mouth. He watches raptly as Derek clenches the muscle reflexively several times, but his hole just opens right back up again and probably won't get back to how it should be for several hours. Maybe not even until the next morning.
Derek raises his head then and regards his mate over his shoulder. "You gonna leave me this empty or what?" he rasps, shaking his hips.
Wrenching himself from his daze, Stiles apologises and positions his hand at Derek's hole again. He pushes it back inside, and it slips in much easier this time. Derek moans his encouragement and fucks himself on Stiles' fist, and together they find their rhythm once more. The rim clamps down tightly around Stiles' wrist every time, but it lets him go easy enough when he pulls his hand back out again, properly fucking Derek with it now. Derek sounds like he's literally getting punched each time Stiles shoves his fist inside, and he reaches beneath himself for his cock.
"You gonna make yourself come?" Stiles asks huskily.
"Y-yeah…so close…" Derek apprises.
"Do it, Sourwolf," Stiles tells him heatedly, beginning to twist his wrist again when he forces his fist in. "Wanna feel you come."
It only takes another few seconds for Derek to obey. He howls as his orgasm hits, and then the lake of clear pre-come expands as thick jets of creamy white jizz land in it. Stiles leaves his fist inside his mate's body while his orgasm racks through him. He focuses on how Derek's ass feels around his hand and on the bitter scent of Derek's come as he jerks himself off as well, and his own orgasm is swiftly upon him.
When it's over and he sees that Derek looks close to collapsing in his own mess, he reluctantly extracts his fist one last time and wipes the lube off on the bedding, figuring that it's ruined anyway. Once that's done, he helps Derek roll onto his side, just avoiding the pool of come so that he can recover from what they just did in comfort.
"How was it?" Stiles enquires, rubbing the hairy leg closest to him.
"Actually pretty damn good," Derek replies softly, a contented smile on his lips.
"So you'd be okay doing that again then?"
Stiles smiles himself. "Maybe you can fist me next time. We already know I can take your knot."
"Sure," Derek agrees, wiggling slightly. "Tired…"
Stiles wants to let him rest, but he knows they'll both sleep better with some fresh sheets, so he drags a complaining Derek into the bathroom to wash up while he strips the soiled bedding from the mattress. He balls it up, throws it into the corner to deal with in the morning and then retrieves a spare set from the linen closet in the hallway. By the time he's finished putting the cases on the pillows, the final step, Derek emerges from the bathroom in a cloud of steam, his hair damp and his body clean and bare.
"Come on, Sourwolf," Stiles says, taking Derek's hand. "Into bed you go. I'll join you once I've washed up too, okay?"
"Mmm…'k," Derek mumbles, sliding beneath the sheets and snuggling in.
Stiles takes the shortest shower of his life, dries off with a fluffy white towel and then rejoins his mate in the master bedroom. He finds Derek on his side, his back to the middle of the bed. From his quiet snores, it's clear that he's already fast asleep. Stiles' heart is filled with affection as he gets into the bed as well and slides close to him, his arms automatically wrapping themselves around Derek's broad body so that his front is pressed to Derek's back. He buries his nose in the back of the Alpha's neck and closes his eyes.
He'd say that the evening was an unmitigated success.