How about Deter (or Stetopher) Biker/student (or nerd) AU?
I’m thinking Stetopher, Biker/Nerd/Jock trifecta?
1. Stiles is the nerd, Peter is the basketball jock, and Chris is the rebel biker who dropped out of school and got his GED instead
2. Chris and Stiles meet when Stiles’ brings the Jeep to the mechanic that Chris works for. He takes one look at the guts of the car and is about to say “junk it,” when he looks up into those big brown eyes. Stiles is already anticipating what Chris is going to say, and he looks heartbroken over it. And somehow, without the permission of his brain, Christopher’s mouth instead says “This is gonna take a couple weeks. You got a ride?”
3. Stiles does, indeed, have a ride, in the form of his smirking next door neighbor. Peter takes him to school in the morning and brings him home after basketball practice/chess club. They swing by the garage a few days after Stiles dropped off the Jeep to check on his baby, and Peter gets to meet Chris too.
4. Chris can see the confident (almost smug) initial interest when Peter looks him up and down at their handshake. But not two minutes later Chris writes him off when he sees the soft way Peter looks at Stiles as he trails after him, catching him every time he trips over tools. Stiles has also apparently read six books about car repair in the last few days and has a shit load of questions. Chris answers them patiently, explaining everything and smiling at how excited Stiles gets about learning new things, rather than mocking him. By the end of their visit, Chris has earned a few of the soft looks that Peter usually reserves for Stiles.
5. Peter visits Chris by himself a few more days after that, saying he’s there to settle Stiles’ bill. Chris raises a single eyebrow.
“Does he know you’re doing this?”
“Is it the kind of surprise that’s going to piss him off?”
Chris sighs. “Let’s work out a deal. I’ve mostly been working on this after hours anyway, so let’s call my labor free, and then you can pay for half the parts, alright? I’ll give Stiles the bill for the other half, and that way he doesn’t feel like a charity case.”
Peter’s mouth drops open. “You can’t just give away what’s gotta be at least 20 hours of work for free!”
“I can do whatever the fuck I want. Now are you paying for your half of the part with a card or by batting your pretty blue eyes?” Chris intended for the second half to sound sarcastic, but something about Peter’s contemplative face makes him think he wasn’t entirely successful.
6. When the Jeep is finally done, Peter drives him to the garage, Stiles practically glowing with excitement. When he sees the Jeep and starts her up, the engine turning over smoothly and the gears shifting easily, he actually sheds a few tears.
Peter knows what the Jeep means to Stiles. He looks at Chris with obvious gratitude in his eyes and nods in thanks, throat a little too tight to speak.
When Stiles hops out of the Jeep he runs over to Chris and plants a kiss on his cheek.
“And I hope you don’t think I’m dumb enough to believe that was actually the entire price of the fix. I’m going to pay you back, but thank you too.” And leans forward to plant another kiss on Peter’s cheek.
Chris and Peter both stare after him, dazed, as he dances back over to his car and coos at her.
They glance at each other, cautious for a moment before Peter’s mouth lifts in a little grin. Chris can’t help his returning smile.
7. So they embark on a joint campaign of seduction. Stiles never stands a chance, having been into both of them from the beginning anyway.
