They both agreed they could—wanted to—keep it casual. It became almost a game to see who could stay the most casual, no matter what they did, what they felt. Derek casually sealed their first kiss. Stiles casually pulled him into bed the first time. Breathing hard, staring at the ceiling with stars in his eyes, Derek asked, "Wanna do that again?" Casually, of course. Stiles rolled on top of him and playfully bit at his chest. "You up for it, big guy?" Days and nights and weeks later, Stiles casually cooked dinner for them both, and Derek made breakfast. Spare toothbrushes were added to each bathroom without fanfare. Early one morning, still pleasantly buzzing from the night before, Derek crept to the kitchen, digging in the bag he'd left on the counter. Stiles was still asleep, arm flung across the bed onto Derek's side. Derek set the key casually in his upturned palm, then quietly dressed for work. His phone was silent all day. When he returned home, there were sneakers by the door, three hoodies in the coat closet, and a note on the fridge: Went to get dinner -S He smiled. Stiles moved his things in and a year later, casually sent Derek listing for bigger places, closer to both of their jobs. They found a larger house, one with a yard and a reading nook for Derek and an office space for Stiles. "I love you," Derek said, casually of course. Stiles kissed him, hands at his waist, nearly sweeping him off his feet. "I love you, too." Just as casual. Six months, hundreds of boxed and gallons of paint later, Derek woke to the scent of bacon and waffles wafting into the room from downstairs. A black velvet box sat casually on his chest.

Fresh off the back of being dumped, Derek agrees to strike up a friends-with-benefits situation with Stiles, his best friend and roommate. It doesn't matter that Derek is straight - it's just sex, after all.

Stiles receives a dick pic from an unknown number. He decides to grab the opportunity with both hands to do something about his pesky virginity.

Derek is a closeted frat boy, and Stiles gets under his skin. Enemies to fuckbuds to <3

Derek is a single parent to a teenager. He's given up on love since losing his daughter's mother. Stiles is an FBI agent in town on the hunt for a feral omega. He might have something to say about Derek's stance on love.

Stiles and Scott become best friends at college. Derek is Scott's hot older brother.

Stiles stares at the ceiling, completely flabbergasted. Derek Hale wants him. For real. This isn’t another Lydia situation, where he needs to pine and slowly try to work his way in from the edges of someone’s life. Derek likes him already. Derek is nice to him. Derek answers his questions and his texts and buys him magical things. He presses a hand against the spot Derek bit and shivers. That action had felt kind of wolfy, like Derek forgot to pretend to be a human man. Maybe that’s it, then, for Derek. Stiles is someone he doesn’t have to pretend to be human with. Maybe after summer ends, after Boyd and Erica are safely corralled in Beacon Hills, Derek will go back to fucking women like Tina or whatever that chick’s name was. Stiles isn’t complaining. He’ll take what he can get. - In which Derek is a magical werewolf boy and Stiles becomes his emissary.

"This is weird," Stiles tells him. His hands are still on Derek's chest. "Is this weird? Are you even sentient enough to think things are weird?" Derek's tail wags back and forth, brushing against his calves and stirring up the fallen leaves. And the licking? It doesn't stop. Derek keeps at it, licking Stiles' cheeks, his forehead, that sensitive spot behind his ears. Stiles tries to twist away, much braver now that he hasn't been mauled, but there's no escape. "Okay," Stiles croaks out. He pushes at Derek's shoulders, his chest. "Let me up, big guy, come on." When Derek doesn't move, Stiles arches up, trying to wriggle free, but then he feels something wet and sticky against his stomach where his shirt has ridden up. He cranes his neck down and sees Derek's dick. It's distinctly non-human; red, with a tapered tip. Clear fluid drips from it. "Oh holy god," he says, horrified and fascinated. "Is that - oh fuck." - In which Derek has sex with Stiles while in the Alpha form

"He's sixteen," Derek snarls. He has Chris bent over the hood of his car, his hand on the back of his neck. He digs his claws into Chris' neck, a reminder that he could rip this man's spine out at any moment. "He wanted it," Chris says calmly, as if he's not pinned to his car. "We haven't done anything he doesn't want." You're just like her, Derek thinks but does not say. He snarls again, animalistic and vicious, unable to speak at all. "He touches me, I don't touch him," Chris continues, and fuck that excuse sounds familiar and vile. Derek clings to his humanity, fighting back the shift. He says, "Stiles should be with someone -" "Like you?" Chris says, smug as a snake. "Tell me, does Stiles like this jealous streak of yours?" - In which Stiles uses other people to make Derek jealous.

“I probably shouldn’t tell you this,” Scott says, eyeing Stiles’ fries. “But Derek Hale is back in town. I saw him at the gas station the other day.” This piques Stiles’ interest. Oh yes it does. Like any good true crime aficionado, Stiles has his favourite case. His pet cold case. His hometown murder. The thing he brings up when he’s tired of small talk and just wants to get real. The Hale Family Fire and the suicide of Katherine Argent. Stiles knows this case inside and out. He’s racked up thousands of karma points on reddit for his thoughtful analysis, his pictures of the crime scene, and of his reporting of local gossip. Beacon Hills is a small town, small enough that Stiles is the only one on the Unresolved Mysteries subreddit to have actually seen the burnt out shell in person. He’ll tell anyone who listens what he finds fascinating about the case. Absolutely no shame. He’s read all of the articles, he’s pestered his father’s deputies for more information, and he’s read every cold case compilation book that so much as mentions it. No one knows this case like Stiles does. - In which Derek Hale is a man with a dark past, and Stiles is completely obsessed with him.

"I'm not wearing a muzzle," Derek snaps. "Look, if you wear this then we're golden! There's no way you can bite through this, Deaton said so." "Oh well, if Deaton says," Derek says snidely. It's a silly argument. Sure, Deaton is shady and enjoys bending the truth on occasion, but unless it's a complex assassination plan he wouldn't lie about this. Something that Stiles knows that Derek is aware of. "There's really no reason for him to lie," Stiles points out. "What's your real problem with it?" "It's demeaning," Derek says through gritted teeth. "What? No! Lots of werewolves have to wear one of these," Stiles says, waving the muzzle around. The leather and clasps jingle. Derek sneers at him. "Wolves who can't control themselves." "Pot and kettle, buddy. Wait, wait," Stiles says hurriedly when Derek turns to leave, "let's just... let's try it, okay? Come on, have I steered us wrong before?" - In which Derek can't control himself while having sex with Stiles and needs to be muzzled.