It started subtly.
Let’s say Derek was sitting on Stiles’ bed when he came home from lacrosse, book open on his lap, minding his own business and waiting for his boyfriend to arrive.
“Derek!” Stiles would exclaim upon seeing his boyfriend, dropping all of his gross, smelly lacrosse crap on the floor. “Darling, I am ready for the sex!”
“Shower first.” Derek would say, completely lovingly and without any eyebrows (Stiles needed to shut up about that. They weren’t that bad.)
Stiles would then comply, and when he was fresh as daisies, they would consummate their love like bunnies.
Derek enforced this regularly, as lacrosse practice was three days out of the week.
“Shower first.” Derek would always grunt as Stiles came at him for a hello kiss.
Stiles groaned. “Every time. I don’t like showering twice, man.”
“Then don’t shower at all, and we don’t have to have sex.” Derek said without looking up.
Stiles let out a frustrated noise. “Fine.”
When that started working regularly, Derek realized that he could use that strategy in more things than just enforcing hygiene.
For example, when they were sprawled out on Stiles’ bed, Derek’s mouth on Stiles’ soft, sweet scented neck, he would stop, pulling back a fraction of an inch, enough to make Stiles whine at the loss of his lips.
“I know, I know, pants off.” Stiles grinned and got his hand fixed on Derek’s zipper before he stopped him.
“No, wait.” Derek grunted, catching Stiles’ hand. “Have you done your homework?”
Stiles groaned. “Dude, don’t make me think about Harris when we’re boning.”
“So you haven’t done it.” Derek deadpanned. “And it’s physics.”
“Damn it.” Stiles slid off of him and fished out his physics textbook. “I hate it when you’re right about shit.”
“So you admit I’m right?” Derek smirked, scooting up behind him and resting his chin on Stiles’ shoulder.
“Don’t let it go to your head.” Stiles scoffed.
“How many practice problems are there?”
“That’s not too many. Maybe I can help you?”
“As long as you’re not too distracting.”
After about six months of trying out his positive reinforcement of “You will get sex when you do what I say.” Derek was starting to lose his touch.
He paused nibbling on Stiles’ earlobe from behind him, their semi-clothed hips pressed together. “You should grow your hair out more.”
“What? No!” Stiles pulled forward and away.
Derek sat back on his heels, shrugging. “Fine, then we don’t have to have sex anymore.”
Stiles narrowed his eyes at him. “Are you withholding sex?!”
Derek gawked at him. “I… I, uh, how could you think that, Stiles?”
“Because you’ve been doing it for like 6 months now.”
“Of course I noticed! You’re not that subtle, you know.” Stiles sat across from him on his bed. “I let it happen because you were doing things for my benefit. I mean, I certainly shower as much as a should now and I’m getting better grades for it, but the hair? Really?”
“I think you look hot with longer hair.”
Stiles cocked an eyebrow. “So? Who cares what you think is hot. We didn’t start this relationship when I had long hair, why would I grow it out now.”
Derek shrugged. “I dunno. I just… I like the idea of grabbing hold of it, you know? Like maybe when you’re on your knees and-”
Stiles lunged forward, clapping his hand over Derek’s mouth. “None of that, please. You’re not allowed to have a filthy mouth when I’m mad at you.”
Derek mumbled something behind his hand.
“What?” Stiles asked, pulling his hand away.
Derek used this opportunity to surge forward and kiss Stiles, both chastely and passionately, somehow. “I love you.” He mumbled against his mouth. “I don’t care what you look like.”
“Even though you want me to grow my hair out.”
“I don’t care, not really.” Derek kissed him gently. “I love you all the same.”