Three times Derek caught Stiles jerking off in the Jeep on the Preserve.

Stiles has a preference for written porn. He also has a thing for Derek's voice. So when Derek finds his erotica collection, this is clearly either the best or the worst thing that's ever happened to him.

Stiles and Derek have phone-sex while Stiles is away at college.

Stiles would say his relationship with Derek is about fifteen percent empty threats, thirty percent sass, ten percent avoiding violence together, and five percent eyebrows. If anyone asked, he would say the remaining forty percent is mutual orgasms. It’s a good thing no one ever asks.

The five times Derek called the Sheriff "Dad" on accident and the first time he did it on purpose.

There's a part of Derek that he hates most of all - it's only caused him trouble. He pushes people away and finds a workaround and it's fine, until the day Stiles goes searching through his things.

Derek works at a porn store. One day, Stiles comes in asking all sorts of TMI questions about different toys. That's where it all starts.

It takes Stiles four days to notice something’s wrong. Well it’s not like jerking off three times a day is unusual behavior. The third day, he has his usual good morning session, comes straight home from Lacrosse and jerks off without even taking off his jeans because it’s laundry day tomorrow and it’s not like he’s got standards. And everyone jerks off last thing at night; it’s like a glass of warm milk for your dick. Stiles has been hit by a jerking off curse. He might not make it through May unscathed.

And with his fingers pressing inside of him and his cock brushing against the sheets and his face in the leather that smelled like Derek, he felt pathetic and desperate all at once. He knew that if he ever got the chance (the opportunity) to be with Derek that he’d ask him to fuck him within half a second. He wanted the older man inside of him and around him and all over him until his senses were so consumed that he was completely senseless. or The five times Stiles fingered himself and the one time Derek did it for him.

Derek smirks at her, eyes hooded as he leans closer still, until his lips are brushing her ear. His breath fans hotly over the curve of her neck and Stiles shudders, knuckles going white as she clasps them together between her legs. “Touch yourself,” he whispers, the curve of his lips a shade too wicked.