The thing is, Derek does get a chance to step away, to distance himself from Stiles and from everything that Stiles entails. He gets an opening to leave it behind and be with someone else.
She's the opposite of everything he was ever interested in. She's blonde, tall, older, she has a smile that's predatory and worldly. She knows what she wants and she's not shy about showing Derek that she's interested. They meet by accident in the diner, as Derek is collecting food for his family while both his sisters are waiting for him in the car outside. She flirts, calls him adorable, licks her lips like she wants to eat him up. For a moment or two, Derek wishes that he was sixteen already so he wouldn't need Laura to drive the Camaro on the food run.
But then Cora bounces in, with all the energy and impatience of a nine-year-old that she has.
"Deeeeeerek," she whines. "You're taking forever."
And just like that, Derek's mind goes to Stiles. With those few words, he's back in Stiles's bedroom and everything that this woman, who didn't even know she was opening a door to get away from that, is forgotten. It doesn't matter that she's pretty, that she obviously likes him -- that she wants him if her lingering glances down his body are anything to go by -- because she's not who he wants, in the end.
Cora's words make him think of just two nights before, when Stiles was waiting for him in the bedroom, sprawled out on the bed in only his briefs, while Derek was changing into his pajamas in the bathroom across the hall. Just like that, his cock twitches at the memory of Stiles rubbing his hands over his chest when Derek walked into the bedroom, poking at his tiny nipples like he was trying to get the same effect that Derek's hands had.
"Ew, gross," Cora mutters under her breath, only loud enough for Derek to hear. "Boys are gross. I'm telling Laura."
With that, she bounces right out of the diner again. Derek knows that he's going to get questions. That Laura will hear about his reaction and assume it had something to do with the woman next to him. He figures it's a good excuse, better than pretending it's just because he's a teenager and gets turned on by everything. Better than ever having to admit anything about Stiles.
"Aw, wait," the woman says, sounding disappointed and almost angry as he grabs the bags and hands the cashier money.
"Gotta go," Derek says hastily.
He walks out without looking back at her. There's a text message on his phone from that morning, the Sheriff asking him to come to watch Stiles for the night. The woman was going to be his excuse, he thought about it the moment she said hello. But now, once he slides into the Camaro and hands Cora the food bags, he pulls out his phone and sends a message back to tell the Sheriff he'll be there and that no, he doesn't mind staying the night.
When he gets to the Stilinski house, he doesn't mention it to Stiles. There's no point, it's not like it went anywhere. But he does kiss the boy a little harder, pinches his little nipples until Stiles is arching up on the bed, his pink lips open in a gasp. Derek puts his own lips on them that night, licks around the buds until they harden and until Stiles's cocklet twitches with another dry orgasm.
"I didn't know that could happen," Stiles says, looking mesmerized when Derek leans over him and peppers kisses over his face.
"Wanna find out what other places do that?" Derek asks, feeling invincible.
He loves that he can do this, that he's the one showing Stiles everything that a body can do, everything that Derek had to figure out by himself. He loves the way Stiles reacts to all the things they do with curiosity and enthusiasm, with eagerness and joy.
He loves Stiles.
The thought hits him like an oncoming train and it becomes vividly clear why the woman from the diner stood no chance. Had he not given in to the temptation of Stiles's body that first night, she probably would have. Derek would have fallen for everything she offered and maybe tonight he would've been the one learning whatever she wanted to teach him. But he did give in and now he's here, knowing there's absolutely no way he'd ever want to be somewhere else. Or with anyone else.
When he kisses Stiles's cheek, it's with a tenderness he didn't show before. When he slides his tongue over Stiles's lips and breathes in the boy's scent, it's with want that he doesn't know he'll ever manage to satisfy. Derek kisses his way down Stiles's body, licking and sucking on the pink and puffy nipples until Stiles is writhing under him with impatience, small whimpers pouring out of his mouth as his narrow hips jerk up and into Derek's chest. Then he closes his teeth around the elastic of Stiles's briefs and tugs them down gently, revealing his cocklet, still so small against the growing balls underneath it.
Stiles yelps when Derek nuzzles into the crevice between the boy's thighs and he nudges Stiles's legs open as he slides between them. He puts his hands on Stiles's hips to stop them from moving and glances up. Stiles is staring down at him, eyes wide and mouth open, hands clutching the pillow under his head. Not looking away from Stiles's eyes, Derek sticks out his tongue and swipes it over the soft tip of his little cock. Stiles yelps again and his eyes turn to the ceiling, then close when Derek does it again. And again. He closes his mouth over the tiny cock and sucks, then revels in the way Stiles's hips jerk up like he's trying to push deeper into Derek's mouth.
He doesn't get properly hard, but the cocklet plumps up a little as Derek continues sucking him off, just enough that there is a difference. After a while, Derek moves one hand between Stiles's thighs and his fingers fondle the ballsac, then dip behind in and stroke slowly towards Stiles's pucker. By instinct, Stiles's legs move apart and then he lifts his knees to his chest, letting go of the pillow as his arms wrap around them, holding himself open.
Derek manages to stop the growl that's forming in his chest and he closes his eyes to hide the blue flash that he knows he can't hold back. Stiles's position makes him move his other hand away from the boy's hips and he braces himself on his elbow, then takes Stiles's cocklet back into his mouth while his free hand fondles his balls and rubs through the exposed crack. He keeps sucking until Stiles's body tenses again and his hole twitches. After a quick suck on his own fingers, Derek rubs around the hole and then gently pushes one finger in, feeling it immediately tighten.
"Der... Der-ek," Stiles whines above him, shifting to push his butt into Derek's face, urging the finger deeper.
Letting go off the soft flesh, Derek moves his head lower and licks around the rim as his finger slowly moves in and out. Then he pulls out, not missing Stiles's protesting whimper. It fades into a gasp when Derek pushes his tongue into Stiles's hole instead, his spit making the slide easier and letting him go deeper. Stiles's heart beats rapidly and Derek can barely hear it over the boy's gasps as he pulls his tongue out then back in and swirls it inside the tiny hole, pressing it against the rim and feeling it relax and open up.
Derek's cock is throbbing as he licks inside, as he opens Stiles up with his tongue. He feels his fingers twinge as his claws are only just staying hidden, knows that his eyes can't be anything but glowing blue. He breathes in as his nose nuzzles into the dip behind Stiles's balls and then he can't hold back anymore. Knowing that Stiles can't see, Derek carefully lets his shift take over just a fraction, just enough for his fangs to peek out -- not far enough to cause damage -- and his tongue lengthens enough that he can press it deeper into Stiles's ass than his fingers have been so far.
"Feels full," Stiles mutters between yelps, out of breath but not unhappy.
That's enough for Derek to go to town, driving his tongue in and out of Stiles's hole as he imagines his cock would. He can't do that just yet, but fucking Stiles with his mouth is enough for now. It's driving Derek to the edge fast, so he puts a hand down to his own cock and strokes it in the same rhythm, up and down as he pushes his tongue in and out of Stiles's ass.
The taste is intoxicating, it's making Derek's mind fog up and just want to keep going, even as Stiles whimpers weakly above him, the hold on his legs getting unsteady. It's only when he hears a hiss and a hint of pain that Derek pulls away and kisses his way up Stiles's body again, tugging his small fingers away to let his thin legs fall on the bed, bracketing Derek's. Stiles looks exhausted and debauched, his bottom lip bitten pink and his eyes wide. There's a sheen of sweat across his face and down his chest that Derek licks at, reveling in the increased scent that fills his nose. For a second, he lingers on the fact that he has no issues controlling his shift, that it comes to him easily -- full moons have been a struggle since Paige died, but now he feels anchored, steady.
It's Stiles, it has to be, Derek thinks as he kisses the boy's lips gently.
His cock is still throbbing and he braces himself on one arm above Stiles while he reaches for his cock with the other. Only a few strokes later he's spurting come all over Stiles's body, drops of it landing across his pale chest, adding to the scattering of moles, others coating his cocklet and the emerging hair around its base. Some of it catches on Derek's fingers and he lifts his hand and nudges Stiles's lips open, feeling his cock pulse again when Stiles sucks two of them in and licks them clean.
Finally, Derek moves and lies on his side next to Stiles, watching his fingers between the boy's lips. Stiles continues sucking them like he's nursing, eyes closed and his hands limp by his sides, legs still open and unmoving. Derek leans in and kisses his temple, following the movement of Stiles's eyes as they open wide and he looks at Derek, his expression dazed. His small tongue follows Derek's fingers as they slip out of his mouth and Derek can't help but smile, then he drops another soft kiss on Stiles's open lips.
"You okay, baby?" He asks, seeing how exhausted and limp Stiles looks, the lack of restless movement unusual for him.
"Mhm," Stiles answers dreamily. "Was nice."
"Felt weird at first, like when I go poop," Stiles says, scrunching his nose. "But then it got super nice. Full."
"Like being full, baby?" Derek asks him, his mind immediately dashing to all the ways that he would want to fill the boy up.
He wants to fuck him, wants to fill him up with come, wants to watch it leak out and then lick it out. When Stiles nods in response, Derek holds back a whimper even as he feels a twinge in his sensitive cock. Instead, he gets up and scoops Stiles's limp body into his arms, brings him to the bathroom and fills the tub, then sits down behind Stiles and gently washes him off, listening as Stiles starts rambling about something from school. Later, they fall asleep the way they usually do, Derek stretched out on the bed, Stiles sprawled on top of him, his body restless as he sleeps.
I love him, Derek thinks, filled with a mix of joy and fear, unsure how to handle his feelings.
When he leaves in the morning, it's with the agreement that he'll be back again to babysit a few days later. The encounter with the woman in the diner is only a faint memory in his mind, until Laura brings it up. Derek just shrugs, mumbling that he didn't even like the woman and that she was too old for him anyway.