When his dad checks him up before going to work, he's still lying in bed next to Laura, one hand on her tummy.
His dad get a look on his face that Stiles can't read before smiling at him.
"Didn't get any sleep, huh?" He says, lying on the door frame.
"Did you?" Stiles fires back.
"Actually, I did." He replies, smiling smugly at him. "It's not the first time I've done this, kiddo."
Stiles smiles back at him.
"Yeah, yeah, you are an experienced old man. A level 100 dad. I get it."
"And don't you forget it," his dad tells him, straightening up. His smile dims a little and he starts looking uncertain.
Stiles is about to ask him what's going on, when he says, "you'll get used to it with time, kid."
And then he's turning around and throwing a take care over his shoulder as he walks away, before Stiles can decipher what the words mean.
Stiles decides, whiles he's changing his first diaper of the day, that if he has to be awake, so does Derek.
So he calls him up.
"'Sup, big bad wolf." He chirps into the phone.
"I will kill you, Stiles." Derek grunts out, and Stiles can hear a faint sound of rustling.
And the last thing Stiles needs is to picture Derek in bed.
"Yeah, sure you will, big guy."
"Kill you." Derek reiterates, and the rustling noise intensifies, as if Derek were just... rolling around in bed while talking with Stiles on the phone.
Stiles swallows and looks down at Laura, who's sleeping. He's pretty sure if she were awake she'd be looking at him with her big eyes and silently judging him.
"Kill me, you will. Okay, Yoda, I get it. Now get your ass up here, we have to go to Deaton's."
He hangs up just as Derek starts saying you little shit.
He smiles to himself as he pictures Derek with dark bruises under his eyes, lying on his bed and cursing into his phone like a normal, everyday twenty something. Like that's the worst of his worries, just losing a little sleep.
Sometimes it's the little things.
"Okay," he bounces Laura a little when she fusses a little, "let's get you dressed up, alright?"
Derek shows up an hour later, when Stiles is feeding Laura her second bottle of the day, so he gets the door with her in arms.
Derek's eyes drop immediately from him to her and his face goes from vaguely pissed off to mildly shocked, eyebrows climbing high and mouth loosening, all bodily movement stopping in its tracks, and then his lips tighten in a straight line and his eyes go back to Stiles (who's leaning against the door frame and giving his best wide eyed innocent look), intense enough to make Stiles feel goosebumps.
"Stiles, what the hell is the baby wearing."
"A onesie?"
Derek's eyebrows do a complicated dance then, before he grits out, "I'm not going out with her dressed like that."
Stiles rolls his eyes, takes the mostly empty bottle away from Laura, and moves aside to let Derek in.
Not that he's moving.
"Stiles, I'm serious," Derek says, crossing his arms over his chest and trying to stare him down.
Stiles splutters indignantly.
"Oh, come on, do you know how hard it was to find a wolf onesie for a newborn baby? If anything, you should appreciate my determination."
"She's wearing a wolf onesie, Stiles. You've put her in a wolf onesie. It's not funny."
"It is, man. And she looks hella cute in it, too. C'mon, don't be like that."
Derek keeps drilling holes into him for a few moments more, refusing to budge, frown firmly in place.
Stiles lifts his eyebrows at him and juts his chin up, all defiance.
Laura squirms a little in his arms, which probably ruins the picture.
Derek looks down at her, however, and... the fight drains out of him. Visibly.
He just... deflates like a balloon.
"It does," he starts, and winces like the words are paining him, doing him this great disservice by falling out of his mouth, "look kind of cute on her."
Stiles' smile is practically torn from him, all facial muscles acting on their own.
He just lets it show, and lets Derek in.
They take Derek's SUV, which Stiles had been expecting.
What he hadn't been expecting, however, was that-
"You have a baby car seat. Derek Hale has a baby car seat. In his car."
"Wow, you're incredibly observational, Stiles. Please tell me more, this is riveting." Derek deadpans, fixing the thing on the backseat.
Stiles would've replied well, fuck you in any other circumstance, but a) he couldn't harness much annoyance at a Derek Hale that only moments ago had been carrying a diaper bag and looking like the surliest first time dad ever, and b) Derek was bending over while he adjusted the car seat in this jeans that were so tight they could've been painted on, and Stiles is only human.
So what he does is look down at Laura, who's awake and sucking on her fist studiously, with a raised eyebrow and mouths the word asshole down to her. Her response is to blink a couple of times and wave her tiny fist around a little.
Stiles nods along, pretending it's a gesture of agreement.
"Stiles," he looks up to Derek, who's finished fixing the car seat and is just... staring at him with an amused glint in his eyes.
Stiles can feel himself blushing, skin growing warm and hot and tight on his cheeks.
"Shut up, you've bought a car seat, you have no room to talk." He snaps, shoving Derek aside with his shoulder to bend down and put Laura in the seat.
"Okay," he gets out as he carefully sets her down and then frowns at the thing and its many belts, grabbing one randomly, "how does this work?"
"Move."
It turns out that having a baby on board makes Derek be the most conscientious driver. Stiles is taken by surprise by how unsurprising he finds this new piece of information.
Stiles also catches him looking at Laura through the rearview mirror a couple of times. The first time he thinks about saying something, making some smartass remark about it, about how the big bad wolf is softening for a baby; has a few comments on the tip of his tongue, things designed to rile him, to push at his buttons, because Stiles is good at that. He's good at getting reactions from Derek, at making him push back like a text book example for the laws of physics.
But he bites it down when he thinks back himself awkwardly kissing Laura's cheek, checking in on her, and feels hypocritical.
"Well," Deaton says after looking Laura over, "she's not a changeling."
Stiles sighs in relief, even though the idea (terrifying as it was), hadn't even crossed his mind up till this moment.
"In fact," Deaton moves on, frowning a little even as steps closer to Stiles and lets Laura grab one of his fingers, "she seems completely human."
"Well, damn." Stiles mutters, and Derek lets out a huff, this loud gust of breath that on anyone else would've been the quelling of imminent laughter.
"There aren't many myths about creatures known for giving magical gifts such as this." Deaton says, calmly picking Laura up with the utmost ease from Stiles' arms (and Stiles' arms feel tingly and odd without her nestled there). "And I've never come across anything like this. This is... quite a situation you have in your hands, mr. Stilinski."
No shit is what's resting on the tip of his tongue, but he bites his lips to keep it in and nods, crosses his arms over his chest for something to do with them, suddenly hyper aware of their weight and length.
When he looks at Derek, he notices that he's tensed up. Not enough to be obvious to just about anyone, but enough that Stiles can tell he's uncomfortable, unsettled.
"I'll look into this," Deaton says, still impassive, and Stiles looks back at him and feels a bit queasy at the thought that by 'this' he might be referring to Laura, "but I'm afraid that nothing will come up, and that you'll just have to default to more... mundane proceedings and avenues of action. Maybe go to your father, the Sheriff?"
Deaton smiles at him then, and hands him Laura back.
Stiles doesn't want to analyze how right it feels to have her back in his arms, snuggled up against his chest in her onesie, frowning in her sleep and drooling a little as she grabs for his shirt.
"I'm sorry I can't be of any more help, gentlemen, but if that will be all, I have patients to care for."
"Well, that was particularly unhelpful," Stiles says as he gets in the passenger seat.
"Worth a shot," Derek replies, putting the key in the ignition.
"So, what now?" Stiles asks, wiggling the fingers of one hand against his leg and bringing up the other one his mouth, to nibble absently at his thumb.
Derek sighs, looking at the rearview mirror and then putting the car in gear.
"Now we do what he says."
"That must be a first," Stiles says, spitting his thumb out to wave his hand around, "you agreeing just like that with something Deaton said."
"It's not like we have other choices right now."
And he's right.
"Well," Stiles cranes his neck to look at Laura, "I think my dad isn't going to be able to explain a mysterious baby apparition away. Especially since special agent asshole McCall came to stir things up."
He looks back at Derek.
"She's gonna have to stay with us."
Derek nods, the look on his face contemplative.
"She could-," he swallows, and Stiles' eyes are drown to his throat, "she could stay with me in the meantime. I could take her in."
"Derek, no offense, but I've seen where you live. That's not an appropriate place for a baby to stay. Even temporally, bud."
He feels like an asshole as soon as the words leave his mouth, and he winces. Derek's face scrunches up for a second, but then it goes to something that looks so close to defeated that Stiles wants to make him pull the car over and just give him a hug.
"Yeah, I know."
"You know," Stiles starts, and looks carefully for his words, softens his voice so it won't sound like an attack, because it's literally the last thing they need right now, "you should look for somewhere else to live. It's not-,"
It's not healthy, he wants to say. It's not healthy, and it won't bring Boyd back. Nothing will bring him or Erica back, and you should stop punishing yourself for this, stop beating yourself up for this.
"- it's not sanitary." Is what he says instead. "I've seen the whole on that wall, and I've seen your bathroom. You should get yourself a real place. One that has four walls. Maybe even a full kitchen."
Derek's face looks dangerously blank for a while, hands white knuckled where they are resting on the steering wheel.
"I know," he mutters after a while, eyes on the road, shoulders tense, "I know. I'm working on it."
"Okay, big guy" Stiles replies, gently.
They end up getting the crib one town over. Derek had wanted to go to the place where he'd bought the car seat, but that was the place where Caitlin worked and... well, Stiles wasn't up to the possible awkwardness of the situation.
Also, it'd probably look suspicious as fuck for them to be buying a crib together.
They make a stop so Stiles can change Laura's diaper and Derek can feed and burp her, and she starts crying just as they are getting to this fancy store, but other than the trip's fairly uneventful.
"It's your turn to calm her down," Stiles tells him as he unbuckles himself once Derek is parking.
"Having a kid is expensive." Stiles concludes as he inspects what must be hundredth crib they've seen.
"Don't they teach that in high school?" Derek asks him, coming closer to him and brushing against his side as a heavily pregnant woman walks by with her husband.
"Nah," Stiles says and straightens up, stopping to fix the little ears on Laura's onesie so they're standing instead of being forlornly dropped to the sides, "they mostly tell us they will eat away our lives, stop our youth in its tracks, and suck the fuck out of the marrow of life."
"That's Finstock, right?" Derek sounds amused.
"Yeah. You had class with him?"
"Econ," Derek moves a little to look at another display, "he wasn't a lacrosse coach back then, though."
"I like this one," He points out at a regal looking rocking cradle that's all dark wood and sleek looking curves with delicate carvings in it, then. "Motion soothes them, they sleep better."
Stiles doesn't even have to look for the price to know that he can't afford something like that.
"I don't have that kind of money in me, dude."
Derek shrugs.
"I'll pay for it."
Stiles smirks at him.
"Does that mean you're my sugar daddy now?" He wiggles his eyebrows, and bites his lip to avoid laughing at the scandalized expression an old woman walking by them gets. "Because if that's so, there's this thing I've been wanting to get for my jeep fore-"
"Stiles," Derek shuts him up, voice commanding. The tips of his ears are red, however, and Stiles feels a blaze of triumph in his chest, warm tendrils of gratification running all over him at being able to get Derek like this. "Shut up."
Stiles only does so because there's an unspoken and mortified please somewhere in there.
(Derek does end up buying the fancy rocking cradle, anyway, and the clerk who rings them up and helps them store the box away in Derek's car oscillates between dispensing politely amiable smiles at them and warm, sincere smiles at Laura all the while and congratulates them on the birth of their baby.
It's surreal.)