Peter is the paradox Stiles can't seem to resolve.
Fed up with unsatisfying research sources, he has started his own version of a bestiary. This one will not focus on abilities and weaknesses and ways to kill. As much as Scott's habit of always assuming best intentions annoys him, many supernatural beings they encountered over the years had been violent out of fear or ignorance, so his most important section is 'optimal lifestyle'. Protecting Beacon Hills will be so much easier knowing what each creature needs to stay healthy and sane (and if it's something morally acceptable).
By all means, werewolves should have been the easiest to write about, seeing as he has several at hand and with Derek grudgingly sharing his own knowledge (though he requests to see proof for Stiles's work as to not be used to only satisfy his curiosity).
But Peter doesn't fit in. He defies their hierarchy, only following the alpha's order when he feels like it, keeps himself separated from the pack without getting scent marked by anyone, and actually goes out of his way to avoid contact if someone comes close to touching him, even by accident. He ought to be an omega, touch-starved and out of his mind — but he isn't.
So Stiles makes it his mission to figure him out. He's just another puzzle unsolved after all and Stiles isn't one to leave those alone.
When Stiles approaches Peter at the next pack meeting, nobody notices. Peter seems surprised he would talk to him outside of pack issues but relaxes after a few minutes, responding in cautious interest.
It's not until weeks later when Stiles doesn't express an opinion to the newest threat due to their heated discussion, that Scott asks him what he's doing. (He only realizes he's being talked to when Scott grabs his shoulder, startling him.)
He looks around, suddenly the center of attention, and shrugs. "Dude, I told you I was working on my own bestiary. Peter's the best source for authentic information." He feels Peter shifting next to him.
Scott's eyes switch between them. "You're sure about that?"
Stiles leans back, his knee bumping into Peter's thigh. "Yeah, I trust him with that." At Scott's hesitance, he adds, "And you trust me. Right?"
As expected, Scott takes the bait. "You know I do."
"So, what's the problem?"
Stiles listens, extracts the key information and tells them the obvious solution. Then he settles back into the couch, ready to pick up his discussion with Peter — who left.
He would like to explain himself but the pack meeting goes on for hours, turning into movie night and with werewolf hearing around, he doesn't want to call him.
When he checks his phone before going to bed, Peter has emailed him photographs of book pages about several supernatural creatures. There's neither text nor subject. He presses call without thinking about it.
"It's half past one."
"And you still picked up."
"What do you want? You can't have worked through the pages yet."
"I want to thank you for that."
"Duly noted. Good night."
"— and to apologize."
Silence, then, "Go on."
"I'm sorry for what I said. I shouldn't have."
"You were not lying."
"No. But I could have given them another reason without hurting you. That's what I'm sorry for."
Peter makes a disdained noise. "You didn't. And I'd rather know people's intents than get paid in pretense."
"That's not what I—" Stiles groans. "I'm only making this worse, ain't I?" He doesn't wait for a reaction. "I wasn't lying, because you are the best source for that but that's not why I— Can you hear my heartbeat?"
"Interesting time to fish for even more information. Well, tact was never your forte."
Stiles huffs and relaxes. "Asshole. I'm only asking if you'll be able to trust my explanation per phone."
"Okay. So. This is not why I started talking to you. Or even why I continued to do so. I like talking to you. I like how you know at least a little about anything and where to find more information. I like how you've got an opinion on everything and are confident to explain your reasoning or change your mind when you notice you're wrong."
"Conceding you have a point does not mean you are right, Stiles."
"But if you hadn't run off in the middle, we would have gotten to that point. Whatever, I just— … They wouldn't get it, you know? If I had told Scott, I enjoy spending time with you, he would have dragged me to Deaton's to get tested for whatever signs of manipulation. So I said the next best thing without lying. It was still an assholey move and I'm sorry."
"Thank you. Unfortunately, I can't stand people who stoop to making words up. I'm afraid we can't continue our comradeship."
"Haha. So will you still come to the next meeting?"
"Let me know when you're done revising the pages. There's much more where those came from."
"That's not an answer."
"Good night, Stiles."
The call ends. He falls back onto his bed, head empty, fiddling with his phone. He's glad Peter accepted his apology. This may have started as a project but he wasn't lying about enjoying his company now.
For a minute, he's wavering between crawling under the covers or taking care of his personal hygiene first, then gets up and starts his computer.
(When he wakes up around ten, he's halfway through the photos and his body is reminding him he's not sixteen anymore.)