Here’s an AU 👀
Established Sterek, Human AU. Derek has been taking self-defense lessons the past few months; a suggestion from Stiles, to help Derek be more comfortable with himself after Kate™️. It doesn’t change what happened when he was a teenager, but it makes Derek more confident, and it’s a way for him to reclaim his body.
Now, I’ve actually already written this exact premise, except Stiles was the instructor. (And the rest of the pack each had their own Thing; together they owned their own gym, it was very sweet)
Instead, this time the instructor is… Mitch. He’s a personal trainer/martial arts instructor that was recommended by John; sometimes he does training seminars for the deputies.
Mitch and Derek get along famously; at first Mitch seems pretty reserved and he can match Derek for sheer Grump Factor, but once he warms up and thaws out a bit, he’s just as sharp and snarky as Stiles. Also Mitch doesn’t ask questions or make assumptions; he’s very good at keeping everything under wraps, the guy is nearly impossible to read. But when Derek comes to him with Very Suspiciously Specific scenarios, asking how one would get out of the situation, Mitch just shrugs and shows/tells him how like it’s no big deal. Derek kind of loves him for it.
Stiles jokes about being jealous over Derek’s new crush on the teacher and Derek is embarrassed but also insists he’s not interested in Mitch that way, but also feels guilty because he kind of is. And Stiles has a habit of pushing things to far, but when he notices Derek getting flustered in a less fun and more extremely stressed kind of way, he backs off.
He still wants to meet Mitch, though, see what all the fuss is about. So next time he’s scheduled to be at the Sheriff’s station for an afternoon, Stiles makes sure to take his dad lunch.
And. Well. He can see the appeal.
Mitch has got that whole ruggedly handsome, looks like he could kill someone with his pinkie but also like he rescues kittens thing going on, and he’s gorgeous, and he’s funny. It’s especially funny that Derek clearly has a type, since Stiles can definitely see the similarities between him and Mitch.
Wink wink. Stiles will have to tease Derek about that later. Gently ofc.
Idk where I’m going with this and it’s alread too long, but the end result: they have a threesome. That’s it. No love triangles or infidelity here; Stiles is totally down, Derek just needs a little nudging to convince him that Stiles doesn’t feel betrayed or jealous or anything, and he’s allowed to have nice things.