So this fic wouldn't leave me alone until I wrote it so here it is! Inspired by this glorious tumblr post (just remove the spaces) – stilesisastudmuffin. tumblr post/27184613905/worstbutt-no-derek-i-do-not-want-that-can

Scott had been five years old when his mom met Richard Hale at the grocery store. He'd recently gotten divorced from his wife and had moved back to the Hale family estate with his son while his daughter had opted to stay with her mother in San Francisco. They'd been reaching for the same box of cereal, bumbled like blushing thirteen year olds, started talking and that had been that.

He'd been six years old when Richard and his son Derek moved in with them.

That was also when Scott's life had become considerably more difficult.

Derek was the older brother Scott never wanted. He was five years older, stronger, smarter, better in school, better at sports… well, better than Scott at almost everything actually. And whenever he wasn't busy brooding in his room or hanging out with his douchey friends (Erica was alright when she wasn't busy scaring the crap out of him) he spent all his time reminding Scott of that fact.

He wasn't all bad, Scott supposed. Derek was actually very protective of him and he was what had kept the bullies away from Scott for most of his life, but since it was more of a 'I'm the only one who's allowed to bully my step brother' deal Scott had still spent the last eleven years of his life covered in bruises, pulling petty pranks to get some form of revenge and seething with rage.

One of the only things that made it bearable was Stiles. Stiles and Scott had met on the playground at age seven when he'd offered to help looking for Scott's lost inhaler so his mom wouldn't get mad at him only to do more chattering than actual searching. They'd been inseparable ever since. They'd also joined forces against Derek since he seemed to delight even more in tormenting Stiles than his step brother, something Scott hadn't thought was even possible.

When Derek went away to college things got considerably easier since the tormenting was limited to the holiday and summer breaks, not to mention that meeting Allison sort of made the world at large rose tinted and easier to deal with. And if Scott noticed that his step brother seemed to magically forget that he owned shirts whenever Stiles was around during the breaks, or that Stiles sometimes tended to stare at said shirtless brother for a bit too long whenever he visited… well, he didn't give it much thought.

He should have known that that would come back and bite him in the ass.

Scott gave a huff of annoyance as he haphazardly parked his bike by the garage and locked it with what might have been a tad more aggression than the task called for. He knew he was sulking but damnit, he could, should have been at Allison's house right now if Lydia hadn't grabbed her at the last minute and demanded they have some 'girl time' and left Scott staring sadly after his girlfriend as she gave him an apologetic look over her shoulder. He wished he had the balls to stand up to Lydia but… no, scratch that – under no circumstances did he want to risk pissing Lydia off in any way. That way laid madness. And probably unimaginable pain and psychological trauma.

Still. Any time spent away from Allison was still a waste in his opinion.

He sighed heavily to himself as he entered the house, stilling as soon as he stepped into the hallway to listen for sounds of other family members (Derek was back for the weekend and one could never be too cautious when it came to him) but the house was utterly silent. No Derek then. Well, at least that was something.

He dug out his phone from his pocket and started dialing Stiles' number as he made his way upstairs. Maybe he wanted to come over to play video games or something.

Suddenly Scott stopped dead in his tracks, frowning in utter confusion because… because he could hear Stiles' ringtone. And it sounded like it came from only a few feet away.

Actually… It sounded like it came from Derek's room.

"Ughhh… wazzat noise? "

Scott's frown deepened. That had definitely been Stiles' muffled voice coming from Derek's room, but what the hell was he doing in there?

"It's your phone, you idiot. Now make it stop or I swear to god I'll throw it out the window."

… And that was Derek, there was no mistaking those grumbling and threatening dulcet tones, but—

"Not if you don't feel like explaining my sudden lack of phone to my dad you won't," Stiles muttered, followed by sounds of shuffling sheets – seriously, what the hell? – and a tired groan. "It's Scott."

"Of course it is," Derek said grumpily. "Decline the call, he can survive without you for a bit longer."

"Are you sure about that? Because I have to tell you that all evidence shows that he probably can't. I am vital to your step brother's continued existence and with that comes great responsibilities – like answering his phone calls and— eep!"

Stiles cut off his sentence with an undignified yelp as more shuffling sheets could be heard before Derek's voice sounded again.

"He's with Allison, he'll be perfectly fine." The ringtone was cut off as (presumably) Derek cut off Scott's call and the dial tone in Scott's ear was silenced. "Now, I don't want to hear another word about my step brother for the next few hours." A low, wet noise sounded through the door and Stiles' breath hitched loudly. When Derek spoke again his voice had suddenly dropped several octaves. "Right now you're all mine."

Scott stood frozen, clutching his phone like a lifeline as his heart raced.

Derek was…

Derek and Stiles were…

Derek and his Stiles were… were…

"What are you doing to my Stiles!" he shouted angrily before making the biggest mistake he had ever made in his entire seventeen year old life.

He opened the door - and promptly became more acquainted with his best friend and step brother's bodies than he had ever wanted to be.

Stiles made a sound reminiscent of a dying animal and promptly pushed Derek off of himself, which resulted in Derek toppling over onto the floor with a pained grunt.

"Um, Scott! Hi buddy, we, um… Hi!" Stiles' wide eyed look would have been comical if Scott hadn't just caught him in bed with Derek. The teen scrambled frantically with the tangled sheets to cover himself but mostly succeeded in getting them even more tangled because, you know, Stiles.

"Oh my god, what are you guys doing?" Scott squeaked as he hurried to cover his eyes with both hands. "Oh my god, never mind don't answer that oh my god."

"Look man, I can explain. Just—"

"I'm not listening to anything you have to say while you're naked with Derek! Oh my god, where's my inhaler, I can't deal with this oh god oh god oh god."

"Get out Scott!" Derek growled, actually growled at him while Stiles seemed to be having some sort of aneurysm on the bed.

"You have nothing to say to me, you bastard! You slept with my best friend!"

"Scott, please," Stiles said and no, Stiles was not allowed to sound that desperate and pleading right now. He shook his head wildly.

"No, I can't… I can't deal with this right now, just… I'm going to Allison's."

He spun around and practically ran out the door, completely missing the hurt look Stiles gave him as he left.

Lydia and Allison weren't being helpful at all. At least Allison was stroking his hair, which was nice, but he suspected that it didn't have as much to do with his problem as with the fact that she just liked his hair. Lydia, on the other hand, just looked up from where she was painting her nails with a smirk.

"Oh, so Stiles finally managed to get into Derek's pants? Good for him!"

Scott frowned at her. "You are not helping at all," he informed her, which didn't seem to bother her in the slightest. "And what do you mean, 'good for him'?"

Lydia huffed in exasperation as she inspected her now blood red nails. "Oh please, Stiles has had a crush on that yummy brother of yours since he was twelve and Derek has always had a secret soft spot for Stiles – it was only a matter of time before he realized that he wasn't a kid anymore and climbed that scrawny thing like a tree."

Scott gaped at her. "Did you know about this?" he asked Allison who just shrugged.

"I'll admit that I've only met Derek twice and Stiles was only there one of those times, but they weren't exactly subtle. The way they looked at each other was… intense."

Lydia laughed. "That's the understatement of the year, Allison - I've seen porn less steamy than the eye sex they've been having. Honestly, it's obscene."

Scott whimpered and Allison shushed him gently as she kept stroking his hair. "This isn't fair," he groaned and hugged his knees tighter against his chest. "Derek always does this! This is just like when we were kids - I'd have thought that he'd grown out of it by now but he's just gotten worse! "

Lydia blinked. "Wait," she said and raised one perfectly plucked eyebrow. "You think this is equivalent to Derek taking your toys?" She gave Allison a disbelieving look. "Allison, I hate to be the one to break this to you but you're dating an overgrown five year old. No, scratch that – you're dating a puppy with misguided territorial instincts."

Allison glared at her, which Scott would have appreciated more if she wasn't so obviously trying not to smile. "Scott," she said gently as she played with the hair at the nape of his neck. "Is that why you're upset? Not because Stiles and Derek slept together but because you think Derek is going to take Stiles away from you?"

"I…" Scott frowned as he thought about it. Was that the problem? He realized with some embarrassment that the first thought he'd had when he'd caught on to what was going on had been to get pissed at Derek for touching "his Stiles". Stiles had always been a safe constant in his life, his best friend, just… his, and now Derek was threatening that constant. "I think so… actually." He scowled. "But I'm also pissed that they didn't tell me. Oh god, they could have been doing it behind my back for years."

"I'd say a month at most, maybe two," Lydia chimed in as she blew at her nails to make them dry faster. "Stiles wouldn't be able to keep quiet about it for longer than that. It's probably breaking his little ADD heart to keep secrets from you – has anyone ever told you how freakishly co-dependent you are?"

"Why don't you just go talk to them?" Allison suggested before Scott could answer. "I'm sure that the sooner you sort this out, the better."

Scott just hummed in silent agreement.

Derek was waiting for him on the porch when he got home from Allison's house.

"Are you done freaking out now?" he asked tightly, his expression calmly disapproving. Scott nodded slowly.

"I guess. I still have a lot of questions though." He hesitated a moment before asking, "How is he?"

"He's been better. He thinks you hate him – he went on and on about bro codes and betrayal and all sorts of things before I managed to calm him down. He was asleep when I went down." Wow, Derek sounded pissed but there was something else in that tone that caught Scott by surprise. He was pretty sure it was genuine concern and since when was Derek even capable of mustering up enough actual human feelings to feel anything like concern for another human being anyway?

"… Are you serious about him? I mean, is this just about—" He winced. "Sex or…?"

"No," Derek replied quietly but without hesitation. "No, it's not like that. He's… he's Stiles. I don't know when 'my step brother's hyperactive best friend' became Stiles but…" He trailed off and Scott didn't push. He didn't need to.

"Okay," he said quietly instead. "Just… okay then."

They were silent for a while as if quietly assessing each other before Derek finally said, "You should go talk to him."

Scott nodded and sighed heavily. "I know." He walked up the porch stairs but stopped just outside the front door to grin widely at his step brother. "If you hurt him I'll hunt you down and kick your ass."

Derek just looked at him in that 'I'm so vastly superior to you it can't even be properly expressed in words but I'll put up with you because your stupidity amuses me' way of his but the corner of his mouth was twitching upwards. "It's adorable how you think that's supposed to scare me."

Scott gave him his sweetest smile as he turned the door handle. "Fine then," he said nonchalantly. "I'm sure Lydia would be delighted to do it for me, you know how she's secretly a mother hen when it comes to him. And Erica was always very fond of Stiles, if I remember correctly."

He had to physically restrain himself from cackling as he closed the door behind Derek's suddenly ghostly pale face.

Stiles was sitting on Derek's bed where he'd left him (but thankfully dressed this time), staring blankly at his phone as he passed it from hand to hand. He snapped his head up with a start and dropped the device when Scott cleared his throat awkwardly. "Hey dude."

Stiles did this weird spasm with his head that Scott supposed was a nod. "Y-yeah, hey man. Um, did you have fun at Allison's then?"

"Lydia said that you've been crushing on Derek since seventh grade." Yeah, that… that was not what he'd meant to say, but at least he'd broken the ice. Somewhat. Cracked it at least.

Stiles started fidgeting with his phone again, pointedly avoiding Scott's eyes and generally being as unsubtle as a person could possibly be. "O-oh yeah? Well she's totally exaggerating, it has so not been that long. Like… maybe eighth grade or something, but seventh? Psh!" He laughed awkwardly and Scott sighed as he plopped down on the bed next to him, trying very hard to not think about what had happened in the very same bed earlier that day.

"Why didn't you tell me?" He asked quietly and it was Stiles' turn to sigh.

"Do you want the list?" He asked wearily and started counting of his fingers. "One – He's your brother and everyone knows that close family members of best friends are as off limits as you can possibly get, right up there with actual boyfriends and girlfriends and exes."

"He's my step brother," Scott chimed in but Stiles waved him off.

"That is so not the point here, Scott, get with the program, geez. Anyway, two – What was the point if I thought that I had absolutely no chance with him anyway? He's so pathetically out of my league that it's actually downright sad that my stupid crush didn't admit defeat within seconds and just lay down and died out of sheer hopelessness. I mean, have you seen those abs of his? Have you seen that everything of his? I know you may not see it what with being straight and almost related and all but damn, he's like the epitome of hotness, man. It's insane."

"Yeah, thanks, I get it!" Scott exclaimed because geez. "Fine, you think he's hot, no need to start spouting poetry about it. And…" he trailed off with a frown and his voice was softer when he continued. "Don't talk about yourself like that, dude. You're awesome, and if Derek can't see that he's so not worth your time." He cleared his throat awkwardly. "Which he, um, obviously can, so…"

Stiles just rolled his eyes. "Yeah, well, that's now. It was different back then, which conveniently leads me to point three." He held up a third finger. "He's five years older than me, Scott. I know that's not a huge gap in the long run and there's nothing wrong with some age difference in a couple, but when you're twelve years old and he's seventeen it's just plain creepy .It was just not happening, and that mentality sort of stuck with me even as we got older. I thought I was always going to be some snot nosed brat to him and I was just going to have to deal with that until I got over him." He shrugged.

"But he's so mean." Scott whined incredulously. "He has always been a total douche to the both of us – I get that you thought he was hot but seriously dude, how did his shitty personality not send you running for the hills?"

Stiles scoffed and ran his hands over his buzz cut wearily. "Believe me, I've been asking myself the same thing for years. But hey, love is supposed to be blind, right? Or, well, stubborn crush in this case." He smiled softly down at his hands and Scott realized with a sudden clarity that it reminded him of the way Allison smiled at him whenever she thought he wasn't looking. This soft, sweet little smile that curved her lips gently like she couldn't quite help herself. "You know how Jackson is scared shitless of Derek?" Stiles asked and Scott snapped himself out of his thoughts.

"Uh, yeah?" He wasn't sure why as Derek had never showed any interest in Jackson at all as far as Scott knew but it was hilarious to watch how skittish he got whenever he so much as caught a glimpse of a leather jacket.

"That's because he threatened beat the crap out of him if he so much as touched me again," Stiles said softly and Scott just stared at him. "We were thirteen. Jackson had pushed me so hard into a locker that my whole side was bruised and Derek found out. He never told me that he'd threatened Jackson, of course, but I overheard them - that guy put the mafia to shame even at nineteen with those colorful threats, it's no wonder that Jackson almost has an accident any time Derek so much as looks at him." He looked up from his hands and met Scott's eyes with a steady gaze. "He looks out for you too, you know. Always has. He's… he's not all bad, Scott. A complete asshole who thinks far too highly of himself, yes, but bad? Not even close."

Scott… did not know what to do with that information, so he decided to just plow on.

"How long have you guys been… a thing then?" Please tell me it hasn't been years or anything, pleasepleaseplease.

"Since the last break so I guess about… um, about a month," Stiles admitted and Scott breathed a sigh of relief. "He saw me having coffee with Danny and then he came over to my house that night with this casserole that he said your mom had told him to drop off when he knows my dad has the night shift on Tuesdays and then he started interrogating me and there was yelling involved and we were kissing and that was that." He paused. "And with that I mean awesome and crazy sex."

Scott groaned. "Because that last piece of information naturally couldn't have gone unmentioned, thank you Stiles."

"Aw, you're welcome buddy," Stiles grinned and Scott was so relieved because this was normal, this was them and he'd been so worried that they wouldn't have been able to keep that ease anymore.

"So you're not, um, pissed or anything?" Stiles asked carefully, grin still in place but more uncertain now and Scott couldn't have that. Every word that came out of Stiles or Derek's mouths just made him more convinced that they were serious, that this was mutual and real and here to stay, dammit. Screw being uncomfortable and jealous, how could he be anything but supportive of them without coming of as a total douche?

"Nah, we're cool," Scott said with a shrug and grinned when he saw Stiles' shoulders drop the last bit of tension. "Just… don't screw with him while I'm in the house, okay? And don't tell me about said screwing."

Stiles gave out a huff of laughter. "Deal," he grinned.

Stiles did not hold his part of the deal, but Scott suspected that that was mostly Derek's fault. The bastard seemed to get some sort of twisted pleasure from constantly reminding Scott that he was fucking his best friend on a regular basis, always making sure that Stiles looked scandalizingly debauched whenever they came back from their dates, leaving obvious and fucking huge hickeys all over his neck and making damn sure that Scott could hear them whenever he was despoiling his childhood friend. Like now for example.

"Ah, yes, right there Derek- Harder you basta— oh, oh, oh, yessssss!"

Scott gave a pitiful whimper of despair, cranked the volume of his head phones up to their highest setting and shoved a pillow over his head for good measure.

Stiles better stay his best friend forever or suffering through this would never be worth it.