"Okay," Stiles says, clapping his hands together as he reads over the directions once again, just to be sure he's got everything exactly right. "According to the spell Deaton gave me, all we have to do is mix all of this stuff together in a blender, drink it at the same time, and then voila, we become a magical baby-making machine."
Derek eyes Stiles warily over the island in the middle of their kitchen, which is currently covered in a multitude of things Stiles has gone through hell to find. "You actually think this is going to work?"
"Of course it will, how could you doubt me?"
Derek just raises his eyebrows, and Stiles rolls his eyes.
"Whatever, you fucker. I've quadruple checked everything, and I made sure all the ingredients were as fresh as possible." Stiles bites his lip, the nerves he's been trying to keep at bay suddenly making his stomach clench. "You do want this to work, right? I mean, I know we've talked it to death, but if you've changed your mind –"
"Hey," Derek interrupts, reaching across the bar to take Stiles' hand. "I want this, okay? I swear to you, I want this just as badly as you do."
Stiles squeezes Derek's hand, giving him a bright smile. "Then let's get this party started."
It takes no more than five minutes to blend all but two of the ingredients together, and the end result is some sort of lavender concoction. Stiles pours it into two glasses, adding the special, extremely rare wolfsbane to one before handing it to Derek. To the other, he mixes in the silvery powder Deaton gave him that will allow his body to carry their baby.
"Last chance," Stiles says, picking his glass up and searching Derek's face over the rim.
Derek quirks an eyebrow. "Bottoms up," he replies, lifting his own glass, and Stiles grins.
The drink tastes a lot better than Stiles expects, though he couldn't name the flavor if he tried. He and Derek finish at the same time, both glasses landing on the counter top with loud clinks. They stare at each other for a moment.
"Is it working?" Derek asks, and Stiles shrugs.
"I'm not sure? I don't really feel any diff – oh."
Derek's eyes widen. "What? What is it?"
Stiles sucks in a shaky breath, his whole body going hot. His dick hardens so fast he feels dizzy with it, and has to place both hands on the edge of the island to steady himself. "Uh, yeah. I'd say it's working."
"Oh," Derek says, blinking, and a second later his eyes widen and his cheeks flush. "Oh."
Stiles stares at him over the island, letting the magic build inside him, until he thinks he'll explode if he doesn't get Derek's dick in his ass right the fuck now. "Oh god," he breathes, stumbling his way around the island.
Derek meets him halfway, crashing their mouths together in a hard, bruising kiss. His claws rip at Stiles' t-shirt until it's in shreds on the floor, and all Stiles can do is whimper and yank Derek's shirt over his head.
"You're replacing that, asshole," Stiles gasps between biting kisses, pushing his sweatpants down to pool around his ankles. He's not wearing any underwear, and he has a generously lubed plug in his ass that he put in earlier in preparation for this moment. He hadn't been sure of what exactly the potion would do, but this spell had used the words heat and desperate desire so this had seemed like a likely outcome.
Derek hums in acknowledgment of the lost t-shirt, his own pajama pants easily discarded…somewhere, Stiles doesn't really care. Pressing close, his dick a hot, hard line against Stiles', Derek reaches around and taps the base of the plug with two of his fingers.
"Fuck," Stiles groans, hips twitching. "Get that thing out of me and put your dick in."
"Eloquent," Derek mutters, but he's easing the plug out so Stiles ignores him. He tosses it to the side and picks Stiles up before lowering them both to the floor. "My knot – I can feel it already –"
Stiles' lips part and he draws in a shaky breath, the intense need for Derek's dick suddenly increasing tenfold. "Now, now, now, don't you fucking hold back on me –"
Derek groans, shoving Stiles' legs open and back, lifting Stiles' ass off the floor just enough to line the tip of his dick with Stiles' ready hole. He slides in with one long, steady push of his hips, and they both shudder.
"Oh fuck, oh fuck, Derek," Stiles gasps, writhing to get as far down on Derek's dick as possible. "Knot me, come on, I fucking need it –"
Derek's eyes flutter close and his lips part, and he's so fucking beautiful it makes Stiles' heart clench. It's the last coherent thought he has; Derek begins to pound into him and Stiles' mind goes blank with pleasure.
Derek leans forward, shifting so that one of Stiles' legs is over his shoulder. Stiles plants his other foot firmly against the partition between the living room and the kitchen to brace himself, opening himself wider for Derek's dick to go balls deep. He cries out as Derek's growing knot tugs on his rim with every outstroke, one hand wrapped tightly around his own aching dick.
Derek shoves in one last time with a quiet, broken sound, and the swelling pressure of his knot on Stiles' prostate sends Stiles over, his dick pulsing as he comes.
"That," Stiles breathes after a few minutes, "was awesome."
Derek whines, grinding his hips against Stiles' ass. Stiles just smiles fondly and cards his fingers through Derek's hair.
They quickly figure out that the industrial size bottle of lube they bought won't be necessary. The magic in the potion is making Stiles' body secrete its own lubrication, which is both freaky and awesome at the same time. Either way it makes things so much easier, because once Derek's knot shrinks enough for them to separate, they barely make it to the recliner in the living room before Stiles is climbing in Derek's lap and shoving himself down onto Derek's already recovered-and-hard dick.
"Stiles," Derek says, sounding like he's in pain even as his hips piston up and he fills Stiles again and again. "This is – I don't know if my body can take this."
Stiles whines and slows down, placing both hands on Derek's chest. "Does it hurt?"
"No." Derek shakes his head. "But that doesn't mean it won't eventually."
Stiles leans in and kisses him, licking into his mouth until he feels Derek relax beneath him. "Just go with it for now, okay? I think it would hurt worse if we tried to stop."
Derek nods, and then slams up into Stiles with no warning, his knot already swelling rapidly.
Stiles cries out, throwing his head back as he grinds down onto Derek's lap. "Fuck, you feel so good to me."
Derek whines, claws digging into the arms of the recliner they're in. There's come from the first time slipping down between their thighs, and yeah, they're going to have to get the chair reupholstered.
Or maybe just buy a new one.
Eventually they make it upstairs to their bedroom. At some point between the fourth and fifth time they manage to fill a picnic basket with water bottles and non-perishable snacks, which, Stiles admits, is something they probably should have thought of beforehand.
The second they're in the room Derek sets the basket by the bed and shoves Stiles face down onto it, not even bothering to pull the covers back. He drags Stiles' ass up and then slams into it, making Stiles claw desperately at the sheets.
"Fuck, you're so perfect," Derek murmurs, rolling his hips hard and leaning down to cover Stiles' back. "So good for me, letting me fuck you like this."
Derek mouths at the back of Stiles' neck, sharp teeth scraping against his skin and claws gently pressing into his hips. Stiles' ass is sore, and so fucking loose and wet that Derek's half-filled knot can slip in and out with ease. Come drips from his abused hole, squelching filthily and drying tacky on the backs of his thighs. Stiles has never seen so much come in his life.
"Gonna fill you so full," Derek says into his ear, making Stiles shiver. One hand slides down and presses against Stiles' flat stomach, holding him in place as Derek hitches his hips, pushing his knot fully inside. "Gonna put a baby in you. My baby. Our baby. I'm gonna breed you until it takes, knot you over and over until there's no doubt left."
Stiles whimpers and comes untouched, Derek growling in his ear as his knot fills the rest of the way, locking them together.
Stiles loses track of time. They manage to keep enough of their wits to make sure they stay stocked with water and snacks, but otherwise they just fuck and fuck and fuck. Sometimes Derek will fuck Stiles while he's napping, and then Stiles will ride him slowly while Derek takes his own turn at sleeping. Sometimes, if they time it right, they'll pass out at the same time.
At one point, Stiles' chest gets swollen and sore and his nipples start to leak. Derek sucks them dry while fucking hard into Stiles' gaping hole, his knot swelling so fast and so big that it makes Stiles cry out. His half-hard dick pulses painfully as he comes dry, and he throws his head back with a desperate sob.
Derek continues to grind against him, making broken, near-feral noises that vibrate through his chest and against Stiles' sensitive skin. It's good – it's so, so good, and Stiles holds Derek close as he fills Stiles' already overflowing ass with more hot come.
Stiles isn't entirely sure what day it is when he finally wakes up without the overwhelming urge to have Derek's knot buried tightly in his ass. He blinks at the ceiling for a few minutes before turning his head to look at his husband. Derek is still asleep, lips parted and breath puffing softly against Stiles' shoulder.
They're both covered in come. Stiles feels completely disgusting, but he's also exhausted beyond belief and he can't quite bring himself to wake Derek up when he's so peaceful.
So Stiles flings an arm over Derek's waist and goes back to sleep, a happy smile tugging at his mouth and a warm excitement for their future settling in his chest.