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Teen Wolf/Monsters Inc. crossover

For saucefactory on tumblr

A/N: Basically, Derek is Sully, Stiles is Mike and Scott is Boo. Also, this is unbeta'd so all mistakes are my own :)

"Come on Stiles, you cannot be serious," Derek gritted out, frustration clear on his face, but then, that was how his face normally looked.

At least, that's how it looked whenever he had to deal with Stiles. The man was his friend and partner and well, quite frankly, he put up with a lot from him. He'd helped him out of jail when he'd walked into a crime scene out of "pure interest, of course" and his father hadn't been around to vouch for him. He'd let him stay in his house for three weeks while he got back onto his feet when he'd been kicked out of his apartment five years ago and he hadn't said a thing when the man just never left. He'd given him a job working with him at Monsters Inc. as his assistant when they'd assisted they needed one and he didn't exactly trust anyone else – well, that was more of something for him, but Stiles had been out of job for two months by this point and if Derek came home one more time to see his kitchen covered in flour, he may have actually throttled him, so really, it was in his best interests.

But this…this was too much.

"It's a human," he hissed out under his breath, glancing around as if to be sure that no one else would hear them.

"He is a baby," Stiles argued back, holding the human baby boy closer to his chest protectively and narrowing his eyes at him.

"Humans are dangerous," he insisted.

The baby took this time to let out a high pitched squeal – one Derek was certain that his sister (and supervisor, and she'd never let him forget that) could hear in the office over – and chewed earnestly on the tassel of Stiles' hoodie. Stiles grinned widely down at the babe before giving Derek a mocking look.

"Yeah, because Scott looks so dangerous," he scoffed.

Derek's eyebrows drew together in confusion. "Scott? You named it?"

"Well, we can't go around calling him 'it' can we?" Stiles defended.

"Of course we can," Derek insisted, "Because we're not keeping him!"

"What else are we going to do?" Stiles demanded, "His door's gone, and we don't even know what door it was!"

"We can find out!"

"You mean, by asking Jackson? Yeah, because that'll go down so well," he rolled his eyes, "He'd kill us!"

"I could take him," Derek stated stiffly, folding his arms across his chest and averting his gaze. Stiles suppressed a smile. He was winning.

"Probably," he conceded, "But that would only bring the Alphas down on us, and not even your Uncle could protect us from that."

There was a long, drawn out silence before Derek sighed loudly and heavily, conquered. He ran a hand over his face and curled a fist under his jaw. "Okay, so what are we going to do? Keep it?"

"His name is Scott," Stiles protested childishly.

"Fine, are we going to keep…Scott…" the name was spat out violently, "…surely his parents are looking for him."

Stiles frowned deeply, and glanced down at the baby in his arms. Scott paused his vigorous chewing for a moment and looked up at him with wide brown eyes, like a puppy. He blinked once and then grinned this wide toothless grin and reached out with chubby little hands to pat and grab at Stiles' cheek. He blew a raspberry and looked surprised when the spit bubble popped. One of Stiles' hands came to run through the thick dark brown curls that sat upon the top of his head and, for the third time since he had discovered the boy who had attached himself to the back of Derek's leather jacket, he felt his heart swell and warm and stutter all over again.

Stiles had always wanted to be a parent. He loved kids and their wonderfully naïve views of the world and, well, he wanted to be a one of those proud parents that embarrassed their kids at every single moment they could by showing up at lacrosse games and cheering the loudest, or going to parent teacher conferences and starting fights with teachers and other parents if they said one thing unreasonable about his child (he'd been that kid that at least one teacher in every year liked to abuse, and he'd refuse that to happen to his child). That, and becoming a big shot on the scare floor, were his life goals, but, well, he'd never found the right person to start a family with. For a time, when he first starting working at Monsters Inc, he thought maybe it would be Lydia Martin, the receptionist at the main desk. She'd been beautiful – still, was in fact, even if she did lose some appeal by falling head over heels for that snake, Jackson – and any child he had with her would be perfect. Since then, his plans had…altered slightly, involving more of the big, brooding next-in-line-to-be-Alpha that was Derek Hale. Not that he knew that. At least, not yet. Stiles had a plan. Well, he had the beginnings of a plan…well, he had the outcome, but that was hardly the point.

A particular hard slap from Scott snapped his attention back to the present time and back to the issue at hand. Scott giggled and pursed his lips for kisses. Okay, this kid was too adorable, Stiles decided as he smiled and inclined his head to take what was offered. All he wanted to do was hold the babe close, protecting him from those that wished to harm him – and for a defenceless human in the werewolf world, there was going to be a lot – and, well, keep him forever. He'd be a good dad, he knew.

'But he already has a dad,' a voice reminded him at the back of his mind and Stiles just held onto the boy closer. The voices in his head were right, of course, and not for the first time either. Scott…he had a dad and a mum and a family who were probably going insane wondering where he was. They'd be worried and scared that something had happened to their little boy and, well, Stiles didn't want to be the reason for that.

Derek watched the exchange silently. He knew what was happening. Had seen it happen a few times since he had met Stiles as a teenager, the boy in his first year of High School while he was in the year above. He was probably thinking about how the boy's parents were feeling – unlike other werewolves, Stiles had this inescapable need to know how others are feeling and, perhaps even more unusual, actually caring about it. Maybe he was doing something selfish for once and wondering how he could keep Scott. He scowled. Damn it, now he was doing it. Scott was a human; he had no place in their world. It was too hazardous for him. He wouldn't survive.

But, he hesitated to think, Stiles does look amazing with a pup in his arms.

He'd always known that Stiles was the mothering type. Had smelt it on him from the first time he saw him across the corridor at Beacon Hills High School, smelling of wood and coffee and flour and just the comforts of home, Derek guessed. Vaguely, he wondered why Stiles didn't have a mate and a family by now. He was old enough to – the pack were beginning to get edgy about finding him a mate and it was only the influence of the Sheriff that has held them back, just like it was only Peter's insistence that he needed to find a mate of his own and only real emotions between Alpha and his mate would help make the pack strong again.

Right now, with Stiles holding the human so close to his chest, arms cradling him and the hold protective, the man just looked…right. Like he was in his element; where he was supposed to be. But not with Scott, Derek decided, no, with his own pup.

'My pup,' his wolf growled at the back of his mind and he purposely decided he was not going to think on that response. Like, ever.

"…Derek?"

Stiles' uncertain and imploring voice dragged him roughly from his thoughts, and he snapped to focus, blinking wildly. Stiles was watching him concerned and Scott…well, Scott was gumming the fabric over Stiles' shoulder. He tried not to think about how cute that was.

"What?" he snapped, his automatically reaction when he'd been caught out. Usually, it would be enough to send a wolf scattering, tail between his legs and whimpering because, really, no one liked the deal with Derek when he was in a foul mood. Unfortunately, that move hadn't worked on Stiles for ten years now.

"Hey, you're the one that got us into this mess," Stiles retorted, "Scott was attached to your jacket, remember?"

Derek tried to suppress a flush. He wasn't exactly happy to admit that an eleven month old human had attached himself to back of his jacket and he'd been completely unawares until Stiles had pointed it out to him, eyes wide and voice stuttering.

"You were the one that told me the just use the door!" He snapped back, "Remember that?"

"Excuse me, you were the one that wanted to work your anger off," Stiles pointed out, "You were shouting at him to get you another door – despite the fact, we'd already used up all our doors for the day – so I got you a door."

"And look what a fantastic job you did, Stiles, because now we have a fucking human to deal with!"

"Don't swear in front of Scott," he scolded, making a show of covering the little ears on either side of the baby's head, "He'll pick up bad habits."

"Why the fuck should I care if it picks up bad habits?" Derek snarled.

"His name is Scott!" Stiles barked angrily.

Scott glanced between the two adults in the room and ever distressed look on his face. He didn't like shouting. He didn't like it at all. His mummy and daddy did it all the time and now 'Tiles and Derrick were doing it. He didn't like it. His bottom lip wobbled and he sniffed loudly. His eyes felt wet and tears began to trail down his pudgy cheeks. Neither one seemed to notice though. They just kept yelling at each other. Scott clenched his eyes shut firmly and his hands clapped over his ears in a futile attempt to muffle the noise.

"No! No, no, no, no, no!" he chanted, with such powerful deficiency and it put a sudden halt to the battle of the two friends.

Stiles looked down frantically to the child in his arms and his heart ached at the broken look on Scott's face. The boy whimpered and let out yet another cry of "no!" Stiles held him closer, burying his face in the hair that smelt wonderfully of baby and human, every cell in his body desperate to soothe the pup's pain. His wolf whined and he wished that Scott was a real pup, if only because the need to scent mark was too much to bear and would definitely silence the tears. But Scott wasn't a pup, he was human, and the nuzzling of faces together, although helping for a moment, did nothing in the long run to actually halt the flow of tears and screams.

Derek looked utterly panicked. "What's wrong with him?"

Stiles shot the wolf a glare. "He's scared. Apparently, he doesn't like shouting."

"Well, whose fault is that?" Derek retorted.

Scott let out another unhappy noise, even louder than the last.

"Get him to stop!" Derek ordered.

"How am I going to do that?" Stiles questioned disbelievingly, "We don't exactly have a manual of how to deal with human babies!"

"He's going to draw attention to himself!"

Alarm flittered across the younger wolf's face before new determination settled in, and he began a feverish rocking of the babe in his arms. He pressed kisses along his hairline and hummed under his breath and, when that didn't work, took to telling him that "everything was going to be alright. See? We're not shouting anymore. No more shouting, I promise. Derek and I aren't going to argue anymore, but please, god, stop crying…"

Derek could hear the shifting of people in the offices around him and the low murmur of voices wondering where the hell that noise was coming from. Of all the ways he wanted to deal with the human problem, this was not it. If Scott was found, he'd be slaughtered, and Stiles and he wouldn't get off any better. Treason wasn't exactly something the Alpha's took lightly. He swallowed around his panic and tried desperately to think of some way out of this. He was an Alpha (well, he was going to be) and if he couldn't deal with one little human, how was he going to cope with everything else that being an Alpha came with?

Unfortunately, he didn't get the chance to think of a way out of this. Oh no, because at that point, his office door swung open and Laura stormed into the room. Her shoulders were hunched threateningly and her expression was something akin to murderous.

"What the fuck is…" she trailed off, her voice dropping in volume, as her gaze landed on Scott. He had quietened at the sight of the new arrival and now, they stared at each other curiously. There was a tense few moments, where Stiles fumbled over his own words to try and think of an explanation for the baby in his arms, and Laura sniffed the air and took a step back in shock.

Maybe she hasn't noticed, Derek hoped.

"Is that…is that a human?" she gapped.

And of course, no such luck, Derek deflated, having to lean back against his desk just to keep standing.

Yeah, they were so fucked.