Sam Winchester was the type of guy who needed someone to be dependent on him. He enjoyed having the feeling of being wanted. Not just wanted, but needed. Once Sam had gotten a dog, thinking maybe something like that could fill the void in his life, but it just wasn’t what he was looking for.
It had all started so simple enough. He and (Y/N) were dating, living in the bunker together, with Dean. Dean was hardly around these days, though. He was always off doing other things, never saying what he was doing. But Sam didn’t worry too much, because he knew he was with Castiel. He knew Cas would keep him safe, or die trying. It had all started with a slip up. Once, in the middle of sex, (Y/N) had called him daddy. She’d immediately become embarrassed about it and acted as if it never happened, but Sam couldn’t get it out of his mind, no matter how hard he tried.
Sam had heard of littles. In fact, he’d done quite a bit of research on them, since that was what he was good at. As soon as he read about littles, and the established intimacy and relationship that could come from a little and either their daddy or mommy, Sam knew. He knew that was what he needed, to fill the void in his life. What he needed so he would feel needed once again.
The conversation had been a little awkward at first, but Sam was relieved to hear (Y/N) had also been interested in doing ageplay. She hadn’t said anything, because she didn’t want Sam to think she was weird, and not want to be with her anymore. (Y/N) thought it would be a nice way to relax, and unwind. The hunting life was extremely stressful. And if she could unwind like this, and it would also help out Sam’s stress levels, she had agreed to it almost immediately.
That had been a few months ago now, and it was getting to be a pretty regular thing. They never did it on the rare occasions Dean was actually home. (Y/N) still ate regular meals - Sam just cut them up and fed them to her. Sometimes he’d even feed her a bottle of warm milk, if she was feeling particularly little or he was feeling particularly nurturing. (Y/N) certainly wasn’t little all the time, but it was becoming more and more routine. Sam could always tell when she wanted to slip into her little space, and he would always try to accommodate it whenever possible. If he couldn’t accommodate, because they were on a case, he would take extra special care of her as soon as she could get away from the stress of all of it. Both Sam and (Y/N) had never been this happy before, and that was how they knew this was good.
On this particular night, (Y/N) wasn’t little, though she kind of wanted to be. She was fighting against the head space, and Sam could tell. He had reassured her it was fine, that she didn’t have to fight it, and yet, here she was. On instinct, Sam had tried to cut up her dinner, and she had almost stabbed him with her fork. She was extremely cranky and irritated - a sign it was either a bad night, or she was fighting a regression.
After dinner, Sam had made a decision. If she wasn’t going to stop fighting against it, he was going to try to get her to slip into it. As (Y/N) was in the kitchen doing dishes, Sam started to slowly sneak up behind her. “The tickle monster’s going to get you... he hears you’re cranky and need to smile!”
A squeak of protest falls from (Y/N)’s lips when Sam’s hands are suddenly against her waist, fingertips pressed over her sides where he knew she was ticklish. “Sam, I’m doing the dishes!” She protests again, still cranky, even though she was trying not to be.
“Dishes can wait.” Sam’s head dips down, his nose nuzzling into her neck and she can’t help but to giggle, her neck scrunching up just a little bit. He always knew just what to do to get her to smile.
(Y/N) had almost forgotten about his hands until they were suddenly launching a tickle attack on her sides. She squeals loudly, spinning around in Sam’s arms so she was facing him, gripping onto his shirt tightly while she squirmed. Even though it was unbearable, it was one of her favorite things, because it got Sam to smile wider than he normally did.
When (Y/N) reaches her arms up to wrap around his neck, he takes advantage of it by sliding his hands up her sides to her armpits. She immediately clamps her arms down, effectively trapping his hands there, which he reminds her in a little teasing tone that drives her even more crazy while his fingers are still wiggling against her skin.
(Y/N) is panting by the time Sam lets up, but one look on his face is telling her he’s not actually done. “I’m going to count to three, and then the tickle monster’s going to come find you and tickle you again!”
She doesn’t even wait for him to start counting before taking off, quickly going to their bedroom and going to hide under the blankets. (Y/N) is starting to slowly slip into little space without even realizing it, thanks to Sam’s silly game. And that was exactly what he had wanted.
Sam stalks down the hallways of the bunker, searching through the rooms he knows she wouldn’t go in just to keep the game going for a while longer. Eventually he ends up at their now shared bedroom, humming out thoughtfully. “Hmm... where could (Y/N) have gone?” He questions out loud, smiling when he hears soft giggles from underneath the covers. “Is she in the closet? Under the bed? Under the desk?” With each question he checks where he mentions, until he finally utters his “Aha!” Moment.
Sam practically pounces on the giggling girl, his hands starting to tickle her wherever he can reach. He’s not even sure where that is, since she’s still under the blankets, but she starts squealing so he knows it’s working. Sam quickly pulls the covers back just a little bit so her head is no longer trapped under them, but once he sees she’s on her back, he’s climbing on top of her.
He doesn’t sit his entire body weight down, knowing that he was far too heavy for that. But he does sit down a little bit on her pelvis area, watching her intently to ensure she’s not in any sort of distress. Aside from the streams of giggles still pouring from her mouth, she seems not to be, so Sam sets about his work. His fingers quickly move to her tummy, then back to her sides. He’s laughing along with her as she’s squirming underneath him.
“Sam I’m gonna —“ (Y/N) gasps quietly between giggles. She had been squirming around underneath him, and where he was sitting he was pushing down on her bladder. (Y/N) knew she wasn’t going to be able to hold it for much longer.
“Better hold it!” Sam teases, planning on only tickling her a couple seconds longer, then letting her up to go to the bathroom.
“No, Sam, you don’t understand!” (Y/N) pleads, and before Sam can even stop, she’s wetting herself underneath him. Her cheeks flush a dark red, her eyes absolutely mortified about what she had just done. (Y/N) usually didn’t even wet herself when she was in little space, she barely wore diapers unless Sam wanted her to. And now that she wasn’t even in little space, she had just done it. She just wanted the ground to open up and swallow her whole.
Sam’s heart almost breaks when a tiny, pitiful, “Daddy...” falls from her lips, along with the saddest look he had ever seen. His heart is continuing to break as he realizes he was the cause of that. He should have just stopped as soon as she said something, but he had thought she could hold on a couple seconds longer. It wasn’t like she had said the safe word - but if she was that close to being in her little space, did she even think about using the safe word?
“Oh, little girl.” Sam whispers, immediately climbing off of her and gathering her into his arms. She’s whining and trying to squirm away, not wanting to get him wet, but he’s firm in holding her there. “My sweet girl. It’s okay. Daddy made you do it, didn’t he? You didn’t do it on purpose, baby. Daddy was bad.” His hand is moving up and down her back slowly, trying to soothe her from the embarrassment and shame she was currently feeling.
“I’m bad, daddy.” (Y/N) whimpers, knowing that only bad girls wet themselves. No, Sam had never told her that, but she’d read things online, and a lot of daddies said that to their little girls, from what she had seen. So that must be true, right? “Only bad girls wet themselves, daddy.”
Sam shakes his head, pulling her tighter against his chest. “Absolutely not, princess. It was an accident. If you had done it on purpose because you were mad at me for something, then that would be bad. But it was an accident, and everyone has accidents. It doesn’t make you bad. You’re such a good girl. I promise.”
He carries her to the nursery they’d set up, deciding this time would be a good time for diapers in case something else ended up happening. That way (Y/N) wouldn’t feel so bad about it, since she was in something designed for it. He grabs her pacifier off of her dresser and pushes it between her lips, before setting her on the changing table. Sam quickly undresses her, using baby wipes to clean her up, before getting her into a diaper and a soft onesie. It was one of her favorites, because it felt like a blanket.
(Y/N) curls into Sam’s chest when he gets done and picks her up from where she’s laying on the changing table. She’s still whispering muted apologies behind the pacifier, and Sam is just continuing to shush her, telling her she’s not bad.
“You’re going to be my little baby today, how’s that sound?” Sam asks, tapping her on the nose gently. He’s keeping his tone upbeat, wanting to reassure her and make her happy again. That was also why he’d decided she was going to be a baby today, so he could give her that extra love and nurturing she needed. (Y/N) just nodded her head in agreement, wanting all of the love and affection she could get.
Sam sets her down in her crib, promising he’s going to be right back. He goes down to the kitchen, and he isn’t even gone five minutes to make her a bottle, but by the time he’s back she’s trying to pull herself up using the bars on the sides of the crib, tears streaming down her face. “Oh (Y/N/N)...” He coos gently, reaching down to scoop her up out of the crib. “I told you I was going to be right back, precious. I just needed to get you a bottle.”
(Y/N) presses her face into Sam’s chest while he goes to sit down in the rocking chair. A soft whine is emitted when he pulls her away from his chest, but soon enough Sam’s got her cradled in his arm and he’s taking out her pacifier to replace it with the bottle.
She looks up at him with sad eyes as she starts to slowly suck down the warm milk. She still felt so terrible for what she had done, but Sam was trying to make it all better. (Y/N) decides she needs to get even deeper into the head space and just not worry about what had happened, so she closes her eyes and cuddles up closer to Sam. Instead of focusing on what had happened, she’s focusing on the warmth in her chest from the bottle and the sound of Sam’s heartbeat with her ear against his chest. Every so often Sam is cooing something to her, and she can’t hear what it is because of how soft he’s saying it, but she knows it’s something nice.
As she continued to drink the bottle, (Y/N) was getting progressively sleepier and sleepier. When she was a toddler she’d usually take a short nap during the day, but when Sam wanted her to be his baby, she ended up sleeping a lot more than that, usually snuggled up right next to Sam; exactly where she wanted to be. “Sleep, gorgeous.” Sam whispers as he takes the bottle from her mouth and gives her the pacifier, smoothing her hair back with one hand. “I’ve got you. I’ll always take care of you.”