"You know," Stiles began, looking away from his book on lore to where Derek rests beside him, nearly asleep. "I know big cats aren't supposed to purr, but you're not a cat…"
Derek lulls his head to the side, opening his eyes and staring at Stile like he hasn't heard some of the questions that come out of his mouth. It's late, nearly three in the morning, and night is usually an Adderall-less time for Stiles. Derek takes it in stride like he's learned to. "They don't."
"So what's your excuse?" It's shot back with nary a pause, like Stiles already had this conversation.
"I don't either. Wolves. We're too fierce and ferocious. We don't ever purr or do the dog equivalent."
Stiles shifts, turning to face Derek and speaking as he closes his laptop and sets it on the bedside table, "Then what do you call that noise you make when I pet your hair."
Had anyone else been around, or had it been at a decent hour to be having any sort of conversation Derek would have said something snippy, indignantly denying the little joy he gets when Stiles cards his fingers through Derek's hair, as it was they were alone and Stiles was always able to see through his words.
Derek simply reached out and wrapped his arms around his lover, nuzzling his face into Stiles' stomach and drawing him closer. "Growling friendly-like," he quipped, enjoying the rumble that coursed through Stiles' body.
"You're a big softie." Stiles whispers, flicking off the lamp and pushing at Derek until they're both settled under the covers comfortably. He brings up a hand until he's curling his fingers in Derek's hair and scratching lightly at his scalp.
A soft growl rolls around in Derek's throat and Stiles grins.
"I'm totally the only one who get's to hear your friendly-like growling."
Derek doesn't respond, just pulls him in tighter, and Stiles takes that for the agreement it is.