Sam doesn't hear it right away, but soon after coming home after being at the library for about an hour he can hear a faint wail. He's moving before he even thinks about it, running up the stairs and feeling like shit, swearing under his breath.
By the time he gets to the doorway of the playroom he can tell Dean's been crying for a while. His voice is hoarse and pitiful. Sam walks in slowly so he doesn't scare Dean even more and tries to smile, kicking himself for not being there there for Dean.
"Hey, sweetie," Sam says.
Dean still flinches, sitting in the middle of the playroom floor, toys all around him. He's still in his pajama pants, but they're soaked with urine. When he sees Sam, he reaches out for him, tears streaming down his face harder than before, bottom lip quivering as the pacifier falls out of his mouth and onto the floor. He's letting out little whimpers as he tries to control his breathing. It's a valiant effort, but when Sam wraps his arms around him, getting to his knees and pulling Dean into his lap, Dean loses his battle and just sobs into Sam's shoulder.
"I'm sorry, baby," Sam says as he rocks them both gently, arms tight around his brother because Dean needs that reassurance he's safe and Sam's not going anywhere.
"Daddy," Dean whimpers.
It breaks Sam's heart. It's his fault Dean's shivering and scared and crying and soaked. He knows Dean falls hard into his headspace, but Dean's never awakened from a night's sleep in his adult bed and fallen into it like this. If Dean's needs to be a little, then he tells Sam or Sam asks him because he sees Dean is stressed and needs a break.
Coming home to a Dean already little is a first, and Sam's decided he's never leaving Dean alone again while his brother's sleeping. He's going to wait until Dean's awake and looking at him with adult eyes.
"I'm here, Dean," Sam says, then gives Dean a kiss on the side of his head.
"Owie," Dean says, shying away from the kiss.
Sam frowns. Dean never shies away from physical affection when he's being little. Sam reaches up and gently touches the side of Dean's head.
"Owie!" Dean says louder, pulling back to scowl at Sam.
"Did you fall out of the big-boy bed?" Sam asks.
"Uh-huh," Dean says, nodding.
Sam is almost ready to cry himself, but he smiles for Dean. Because all of this is about Dean and his needs. Dean has taken care of Sam his entire life, been there for him, and if all Dean needs is for Sam to be the big brother once or twice a month for a few hours, then Sam's going to do it.
Thankfully the knot on Dean's head is tiny. It's no doubt sore, but if he makes too big of a deal out of it, Dean will become unnecessarily upset, so Sam will casually slip some Tylenol into Dean's milk later.
"I've got an idea," Sam says, then leans in and kisses the end of Dean's nose. Dean smiles, ducking his head a little. "How about we go take a tubby, get you into a diaper and some new 'jamas, then we'll go downstairs and finish off that pizza from last night? Does that sound like a good idea?"
"Yeah," Dean says, nodding, his smile getting even bigger.
Sam chuckles. "That's my good boy," he says as he wipes the tears from Dean's face. "You've got some new toys to play with in the tub, remember?"
Dean gasps, eyes widening because yes, he does have some really cool new toys to play with. He'd blushed and looked at Sam with a sheepish expression on his face when Sam had tossed them into the cart during the last shopping trip, but Sam could tell Dean had been excited even as an adult, looking forward to when he'd be able to play with his new squeezy race cars.
"Cars!" Dean says, former trauma forgotten as he climbs off Sam's lap and starts pushing his pajama pants down, eager to get into the tub.
Sam doesn't care about the nudity or cleaning up after Dean, dealing with dirty diapers and snotty noses. Dean did it for him. Dean's done so much for him. His brother deserves this, and as Sam reminds Dean fairly often, Sam's more than happy to do it for him.
"Tubby!" Dean says as he gets to his feet and takes off running for the master bathroom, streaking through the house.
Sam can't help but laugh. It's adorable, and it's something Dean would do anyway even if he wasn't being a little. But as Sam follows him in, finds Dean standing by the tub with a hopeful expression on his face, his body nearly vibrating with excitement, it's obvious this isn't adult Dean.
"Not yet," Sam says because Dean tends to get so impatient that he gets into the tub before Sam can get the water going, before he can regulate the temperature.
"Now," Dean says, and yes, it's a demand. But Dean doesn't usually go beyond some impatience.
Sam's never had a problem with Dean throwing a flat out tantrum, Dean's never screamed at him or hit him, and if anything, Dean's calmer, quieter, and happier than he is when he's an adult.
"Just a minute," Sam says, patting Dean on the back before leaning down and starting the water.
"Now?" Dean asks, shifting from foot to foot and poking Sam in the side with his index finger. "Now?"
Sam straightens up again and takes Dean by the wrists. "Okay, now," he says, helping Dean in.
Dean's a big guy, and they figured out early on it just wasn't a good idea for Sam to carry Dean everywhere. He can lift his brother, and he does sometimes, but Dean seems to enjoy having a bit of autonomy, and Sam's back and arms don't give out.
That doesn't stop Sam from rocking him to sleep, holding his brother and watching as his eyes get heavier and heavier. Feeling the weight of Dean on him as his brother's body completely relaxes in sleep. Patting his diaper-clad bottom when Dean makes noises in his sleep.
Sam doesn't bother washing Dean's hair when he's a little. Dean doesn't like it, and he's never been stuck long enough in his little world to make an issue of it. But Dean loves playing in the water, so Sam usually makes sure tubby time is part of the activities whenever Dean looks up at him with those wide eyes and calls him Daddy.
"Cars!" Dean says before his butt is even settled in the tub.
Sam chuckles. "Yeah, I'll get the cars," he says, making sure Dean's steady before turning to grab the bag of cars. He dumps them into the water, smiling as Dean lets out a noise of sheer excitement and immediately starts playing with them.
"Bubbles!" Dean says without even looking up from the cars.
"Please?" Sam says.
"Pease," Dean says, meeting Sam's eyes and giving him his most charming smile.
"Good boy," Sam says, grabbing the bottle and dumping some bubble bath in.
He doesn't always make Dean say please and thank you, but there's a part of him that worries indulging his brother too much will lead to attitude problems, and Sam really just wants Dean to have as much fun as possible when he's little instead of needing to scold him.
Sam lets Dean play until his fingers are wrinkled, then uses his secret weapon. "You ready for pizza?" he asks.
Dean would've gotten a little pouty had Sam simply told him it was time to get out of the water, but using the pizza works wonders.
"Yeah!" Dean says, dropping the car into the water and trying to stand up.
"Hey, wait for Daddy," Sam says, reaching out and getting a hand under each of Dean's arms, making sure Dean doesn't fall.
Once Dean's standing, Sam unplugs the tub and grabs a big, fluffy towel, wrapping his brother in it. He lifts Dean out of the tub, setting him down on the bathroom rug and toweling him dry all over.
"Cars!" Dean says.
"Cars are for the tubby," Sam says. "Let's leave them in here."
"No, cars!" Dean says, then takes off running for the playroom.
"Oh, cars," Sam says to himself, rolling his eyes. He remembers getting the pajama pants with race cars all over them. Another thing Dean had tried to ignore as Sam put them in the cart.
By the time Sam walks into the playroom, Dean is standing there with the race car pajama pants in his hand, grinning.
"Diaper first," Sam says. He would never given Dean a hard time for wetting the pajama pants he'd had on earlier, but he knows it was uncomfortable for Dean, so diapers need to come first.
"'K," Dean says, then lowers himself onto the changing table.
It's a custom table built by Dean and about the height of a coffee table, making it easy for Dean to get onto. It's also convenient for Sam, who could easily do anything he needed to Dean while he was on the padded top.
Dean lay on his back, planting his feet on the table and unabashedly spreading his knees for Sam. Sam dusts Dean's crotch with some baby powder, then pulls out a diaper from one of the compartments in the table.
"Lift your butt," Sam says, smiling when Dean does as he told. "Good boy."
Dean smiles back, aglow with the compliment as Sam slides the diaper under his butt. He relaxes again, watching carefully as Sam tapes the diaper securely. He always watches, and Sam wonders if Dean just likes to watch or if even as a little he's making sure Sam knows how to properly fasten a diaper.
"Wait a minute," Sam says when Dean starts to sit up, then he holds the pajama pants up in front of his face. "You can't forget these!"
"Cars!" Dean says, lifting his legs as Sam puts the pants on him.
"Yeah, cars," Sam agrees. "They look pretty cool."
"Yeah!" Dean says, checking them out as Sam sits him up.
"You wanna pick out a shirt to go with those?" Sam asks.
"No," Dean says, shaking his head, a scowl on his face.
Dean doesn't really like clothes all that much. Not when he's at home relaxing. Most of the time he walks around in either his boxer briefs or his pajama pants, and little Dean is no exception to that rule.
"Do you want me to pick out a shirt?" Sam asks, and he's teasing, but Dean's always up for some light teasing.
"No," Dean says, his scowl deeper.
"Hmm, do you want Puppy to pick out a shirt?" he asks, gesturing toward the stuffed dog he bought for Dean after the first time they tried this out a few years ago.
Dean chuckles, the scowl disappearing at the silly suggestion. "No!"
"Well, how are you gonna eat pizza without a shirt on!?" Sam asks as if he's shocked.
"No shirt, Daddy!" Dean says, pulling on Sam's arms as he hefts himself off the table.
"Well what about socks?" Sam asks.
"No!" Dean says. "Pee-zaa!"
"Oh, you just wanna eat in your pajama pants?" Sam asks as if it's a silly suggestion.
"Yeah," Dean says, nodding as he yanks on Sam's left wrist, pulling him toward the door.
"So no bottle? Just the pizza?" Sam asks.
Dean freezes, eyes going wide. "No?" he asks, tears welling up and his bottom lip wobbling just a bit.
Okay, Sam took the teasing a little too far. Dean loved sitting quietly at night with Sam, rocking as he had a bottle before bed. Sam loved it too. It was a special quiet time for them both. A time when they settled down after a day of playing hard and were getting ready to transition into adult Dean again. It was a way to say goodbye to little Dean until the next time without making it upsetting or abrupt.
"You can still have a bottle," Sam says, pulling Dean close for a hug. "Daddy was just teasing. I'm sorry."
"S'ok," Dean says, pulling away from Sam with a smile once more pulling at the corners of his mouth. "Love you, Daddy."
"Love you too, little one." Sam leans in and kisses Dean's left cheek. "I've got an idea."
"Huh?" Dean says, already yanking Sam toward the stairs.
"How about you pick out a movie while I warm up the pizza?" Sam says.
"Yeah!" Dean says, his grip on Sam's wrist tightening with excitement.
"Okay, look through your movies, not the big-boy movies," Sam warns.
"'K," Dean says.
Sam chuckles as Dean lets go of his wrist at the bottom of the stairs and heads straight for his box of movies, dropping down onto his knees and fully engrossed in choosing just the right cartoon.
No, Sam doesn't mind doing this for Dean, and he'd be lying if he said he got nothing out of it himself.