I own nothing. Based on a Tumblr Anon's prompt.

i. Tony Stark

Tony knew he shouldn't, that he really, really should not be, but he couldn't help it. It was just too goddamned cute. So he laughed, and the subject of his laughter turned, eyes set in daggers. "This is just too precious." Tony squatted next to where Bruce was examining the little toddler currently swamped in one of Tony's old shirts. "How old do you think he is?"

"Two, maybe three." Bruce said, pulling his stethoscope down. "As far as I can tell, all of his functions are working correctly. He's just… de-aged."

Steve sighed and ran a hand through his hair. "So you think it was that alien ooze? But it got on all of us, and the rest of us are fine."

Bruce shook his head. "It was definitely the alien ooze. And it didn't get on all of us. For you, Tony and Natasha, it got on your suits. For me, well… It got on the Hulk, and I don't think it affected him in any way. And Thor is a god. For all we know, he could have de-aged as much as Clint has, it's just that it made no difference as to how he looks."

"You guys don't have to talk like I'm not here, you know." Clint said, crossing his arms across his chest. When he was larger, older, the movement was petulant enough, but Clint had always managed to make it just look annoyed instead of petulant. But now, as a toddler swamped in a shirt that was falling off of one shoulder and hanging precariously on the other, it just looked, well, adorable. "How come my brain hasn't gone back in time with the rest of my body?"

Bruce hummed. "It must be because memories and knowledge are electric waves in your brain. A lot more difficult to get rid of pulses that are always flashing on and off. That's a guess, though."

Clint nodded. "Pretty sound one. How long do you figure I have in this body?"

"Sorry, Clint. I really have no idea."

Natasha grinned sadistically from where she was standing behind Clint. "Well, then. Might as well get you some new clothes, huh?"

Clint looked scandalized.

And of course Tony was not going to miss this, because how effing could he? He didn't even care that the press would be all over him, Tony Stark and Pepper Potts shopping for baby clothes together, a blonde toddler in their arms. He could see the internet already. Blonde! But neither Tony nor Pepper are blonde! Could this be an adopted child?

Clint, for his part, was sulking. He wasn't struggling or anything in Tony's arms, but he was frowning and pouting and downright sulking. It didn't help that every store they went to, every employee cooed at Clint as if he was a real toddler. So Clint kept sulking, his tiny fists squeezing tennis ball-sized wrinkles into one of his best suits, the one Pepper insisted he wear when he was out in public with her.

Honestly he couldn't bring himself to mind, because he'd said it before, but Clint was so goddamned cute. "You know," he said, grinning down at Clint, who sulked down at the buttons of his three-piece suit, "you can try giggling and smiling for the cameras."

"Oh, god, there's going to be physical evidence of this?" Clint groaned, burying his face into Tony's shoulder. He was dressed in a dark blue hoodie that was a little loose for him, along with beige pants, and he looked like one of those baby models that came right out of a catalog, which was probably what Pepper had been aiming for. Tony had originally wanted to buy clothes that were the usual he'd seen – a sweater vest pulled over a button up, with jeans. But Pepper had pointed out Clint had never liked restrictive clothing as an adult, so there was no way that Clint was going to like that now.

And she'd been right. The moment Tony had pulled out a sweater vest, Clint had stared like it held all the horrors in the world. So Pepper had very tactfully displayed the navy hoodie, along with the beige pants. Tony didn't think the clothes were too special – despite the fact that they cost probably more than all of Clint's previous wardrobe put together – and so it must have been Clint that was pulling off the model-baby look.

Clint was, in all honesty, an incredibly gorgeous toddler. Tony could have predicted that, since Clint was an incredibly gorgeous man, but added on with the pale skin yet unmarred by the sun, pale blonde hair and tri-colored eyes that were as big as saucers, Clint looks like a baby that has been heavily photoshopped and brushed over right from a baby catalog.

"If we met when you were this little," Tony said, a little dazed, "I think I would have adopted you."

"Tony, I'm going to remind you that you're not that much older than me." Clint rolled his eyes. "But yeah, I was a pretty cute baby. I remember walking down the street, holding onto my mama's hand, and people would always comment. I mean, that was before my mama stopped taking me out anywhere because pretty soon I got too many bruises and cuts from my pop's drinking, you know?"

Tony winced. Right. Alcoholic father. "I would have taken good care of you, if you were my son."

Clint sighed and nodded against Tony's shoulder. "Yeah. I know." His head nodded almost comically, and the seriousness of the mood lifted as another burst of affection burst through Tony at the sight. "Damn it." Clint pouted, rubbing at his eyes with tiny fists. "All this body wants to do is go to fucking sleep."

The profanity spilling from baby-pink lips was almost hilarious, but Tony swallowed the laugh and patted Clint's back. "Yeah, go ahead and sleep. Looks like Pepper's going to be at it for a while." Clint grumbled something against Tony's shoulder, but soon Tony felt the steady rise and fall of the body underneath his palm.

Normally, he would have been bored out of his mind accompanying Pepper on one of her shopping sprees, but today he was fascinated. Clint was warm against his neck, the way toddlers always were, and he had begun to suckle on his thumb. Muscle memory, Tony guessed, amused to the fullest. He had to get a picture of this somehow. He fussed with his phone for a bit, but the movement made Clint mumble and stir, so he froze until Clint settled against his shoulder again. Tony managed to snap a picture of baby-Clint, thumb sucking and all.

"He's going to hate you for that." Pepper sang, two more bags of baby clothes at her arms. "I think I'm good for now."

"You don't even know how long he's going to stay like this."

Pepper pulled a face. "True, but he's so adorable. And at least this way, the next time something like this happens, we'll be prepared."

Tony snorted. "I think it's a scary thought that turning into a two year old is not the scariest thing that could happen to us."

Pepper only chuckled as she swept up the other bags and handed them for some staff to be delivered back to the Stark Tower. "So it's settled, then? He's two?"

"Bruce says he's closer to two than three. Should be just over 24 months old. It's not that hard to pinpoint a pretty close range, since when you're this small your body changes pretty drastically over a short time."

"He's pretty cute." She leaned over and put her hand on Clint's cheek. "Aw, look at that, he's sucking his thumb."

"He's the most fucking adorable thing I've ever seen, and that seal thing you showed me last month was pretty damned cute." Pepper didn't bother hiding her grin, and Tony knew a similar one was spread out on his own face.

"Well, would you look at that." Bruce chuckled as Tony walked into the common area of the tower. "Here, thought you might want to see this." Tony one-handedly caught the paper slid at him, shifting Clint into his dominant arm expertly. A photo of him and Pepper, with Clint in his arms and sleeping soundly, graced the front cover of the New York Post.

Tony rolled his eyes and shifted Clint's weight again so he was holding him with both arms. "They really have nothing better to do. He's been sleeping all this time, is this normal?"

"He's a toddler, Tony. All they do is eat and play and sleep. He'll be fine, but he can't sleep in that huge bed of his anymore. He'll tangle himself in the sheets. Maybe suffocate himself in it."

"So of course you thought of a solution." Tony grinned, and Bruce grinned back a little tentatively, as if he knew Tony was not going to like the answer. Tony sighed. "What is it?"

Bruce smiled apologetically. "Well, I built him a smaller bed, which was easy enough to do, but he can't sleep by himself, or with either of us, or Thor or Natasha." When Tony scowled, Bruce hurried to explain. "Tony, you and I work late at night, and sometimes with materials that may not do so much damage to adults, but have frightening effects on children, especially ones as young as Clint is right now. He can't sleep with Thor because, well, Thor snores like a freight train and sleeps through everything. If Clint wakes Natasha up in the middle of the night, she may react violently."

"So he has to sleep with Steve."

Tony turned a head toward the super soldier, who looked a little too proud as he reached out for the sleeping toddler in Tony's arms. Tony had half a mind to run away to his room and lock himself in there, but he knew Bruce was right – he played with too many dangerous chemicals for a toddler, albeit one with a mature mind, could live safely. Still he grumbled as he slid Clint into Steve's arms, and took immense satisfaction in the way Clint fretted in the new arms until he woke up blearily.

ii. Steve Rogers

Steve could tell why Tony was so infatuated with baby-Clint the moment Clint rubbed his eyes as he woke up. "Oh, hell no." Clint muttered, and Steve laughed. "Was I really sucking my thumb?"

"Yeah." Steve carries Clint easily in one arm – one hand, even – as he walks into his room. "Bruce made you a new bed, and you're gonna be sleeping in here."

Clint rolled his eyes. "So you can take me to the bathroom if I gotta piss or something like that?"

"Hearing a toddler talk like this really is bizarre, but yes, for things like that."

Clint rolled his eyes again in reply and tugged at Steve's arms. "I want down." Steve put him down gently, squatting so he was as close to the floor as he could be. Clint walked precariously on his two feet and then gave a short cry and reached up to snag Steve's pants. Steve tried not to think about how Clint barely reached his knees. "God, this is embarrassing."

"I'll pick you up again?" Steve suggested, and Clint mulled over it for about three seconds before reaching his tiny arms upward. Steve grasped him gently around the waist and lifted him up easily. "Don't be embarrassed, it's just that your muscles de-aged. Bruce whittled your age down to just over 24 months, meaning you can't have been walking long."

Clint sighed but rested his head on Steve's chest. "It's also sort of humiliating you can pick me up with a hand."

"Relax, Clint. Bruce said you're on the thin side when it comes to babies your age." Clint groaned at the word 'babies' and Steve smiled. "Learn to enjoy it. From what I could tell, Tony's going to be pampering you until you grow back. Just think of it as a nice break. You're pretty cute, you know."

Clint grumbled against Steve's heart, which was quite frankly too endearing. "I'm tired again." Clint announced, and Steve smiled. "I slept the entire fucking day and I'm tired already. How is this possible?"

"Let's just get you changed into your pajamas. Miss Potts gave me this bag."

"Why the hell is it sunflower yellow?!"

It turned out the pajamas were not sunflower yellow – they were more of the baby chick yellow. Steve couldn't help but grin like a proud parent as he tugged the large yellow hooded shirt down over Clint's constantly cursing lips. As he did, the hood caught on Clint's head and stayed over it while the rest of it went down.

Clint glared murder at him, but Steve couldn't help but laugh. "Where did Pepper even find this?" Clint's pajamas – they weren't quite pajamas, Steve thought, since it was just one big shirt – were a bright yellow. It was a long, short-sleeved shirt, with two black-outlined wings drawn in the back. The hood had a small, red-felt beak at the edge, along with two black dots for eyes. Complete with the androgynous looks a toddler usually had, Clint looked like a baby girl. Which was, if Steve thought about it, the effect Pepper might have been aiming for. "Clint, please let me take a picture. You just… It's that you just…"

Clint pouted up at him and Steve was going to be damned if that didn't just make the perfect picture. "I'm not supposed to be cute, Steve. Whoever heard of a cute assassin?"

Steve slipped his phone out and snapped a photo of the pouting baby chick, and Clint tried to stomp on his toe. "Clint, you're currently a two year old. It'd be weird if you weren't cute." He chuckled and took another snapshot as Clint's impossibly small mouth opened in a yawn, revealing an even smaller tongue and a tiny set of teeth. Clint tried to stomp on his toes again. "Let's get you to bed."

He picked Clint up easily again and lowered Clint into the small crib that Bruce had made. Clint looked around at the bars and frowned uneasily. "Can – can I sleep in your bed?"

Steve frowned lightly. "The bars are there to keep you from falling, Clint. My bed doesn't have that."

"I know, but…" Clint stood up and reached up again, blinking his eyes wide. Steve had to repress a chuckle. Always the top-class assassin, Steve thought. Using all the tools he has at his disposal. Steve couldn't refuse him as he picked him back up. "You aren't going to sleep yet, right? You can keep me from falling off the bed."

Clint's moon-eyes that Steve decided were too large for his face pleaded with him, and Steve sighed. "All right. But you're going back to the crib when I go back to sleep. I move when I sleep, and I don't want to crush you."

Clint grinned cheekily. "Yeah, that's fine. By then I'll be too sleep drunk to notice." He tugged on Steve's arm and Steve let him down on his bed, marveling at how small Clint looked on the large bed. Clint scrambled over to one of his pillows – which was easily bigger than Clint – and snuggled into it, sighing contently. Steve counted to thirty seconds before the turned-toddler fell asleep, his thumb unconsciously returning to his mouth.

The alien-ooze actually was doing them more good than bad, Steve thought softly, if it was giving Clint time to actually rest up.

It wasn't until two hours later that Clint sat up slowly. "Clint?" Steve looked up from his lamp. He'd dimmed the rest of the lights, and when Clint blinked at him, he stood. "What's wrong?" He wondered if he should call for Bruce and feel for a fever, but Clint shoved his arms up at him.

"Bathroom." Clint said simply, and Steve forced a chuckle down. He picked Clint up easily. "I don't need help in there." Clint mumbled sleepily, lax against Steve's chest. "That'd be just embarrassing."

"The toilet is a little big for you right now."

"I'm an assassin, Steve. I think I can manage. Plus, you can stand right by the door so you can hear me if I – Jesus Christ – fall in." In the end, Steve acquiesced, and Clint didn't lock the door. But as Clint promised, Steve heard the toilet flushing and the water running before he really even had the time to be worried. He opened the door to find leaning over and rubbing his hands on the towel, feet on wet puddles in the marble sink.

Steve stood ready to catch Clint immediately just in case he slipped. He didn't, but stuck his arms out to Steve again. Clint curled up almost immediately in his arms and started to suckle on his thumb, and Steve chuckled. "I'm going to put you in the crib now. Don't want to wake you up later."

"Mmkay." Clint answered, only half-awake. When Steve lowered Clint into the crib and pulled the baby blanket over him, Clint turned on his side and his small fist clenched into the blanket. Steve took another photo of the sleeping toddler and grinned as he settled into bed with a book on his lap.

He carefully carried the crib to the common area the next morning. Bruce carefully fretted over him, checking temperature and listening to breathing and heartbeat. "Seems okay." Bruce declared with a smile. "How'd he sleep?"

"He woke up once to go to the bathroom, but that was it."

"Mm, good. He's not really at the age where they wake up every two hours, anyway."

Steve frowned lightly. "But he sleeps pretty often. Is this normal?"

Bruce nodded with an easy smile. "He's a toddler. All they do is eat, sleep and play. And since I don't think Clint is really up to playing or anything else he thinks is too childish, he's just going to be eating and sleeping. He'll wake up once he smells food." Bruce raised an eyebrow at him. "It's almost like you're his parent. Both you and Tony."

It was Tony who answered. "That'd make us husbands, so no thanks, Bruce." He swooped down onto Clint and froze. "Oh, God, Pepper." He crooned. "How'd she find something so fitting?" He gently picked Clint up and Clint's eyes opened blearily. "Oh, God, Clint, look at you. I need pictures."

Clint batted Tony away, kicking uselessly with tiny feet that Steve just then noticed. It was impossible, Steve thought, that a person's feet could be so small. "Go away." He pouted. "I'm sleepy. Steve has pictures." Tony glared at Steve, but tucked Clint into the crook of his arm and pulled him up to his chest so that Clint's chin was resting on his shoulder. Clint fell asleep almost immediately, the hand finding to his lips again.

Bruce rolled his eyes. "I analyzed the ooze yesterday and found an antidote, but something tells me you two don't really want me to have found it."

Steve eyed Clint, contently sleeping in Tony's arms. "Will the effects wear off?"

"Yeah. Chemical analysis shows that the compound should leave him in a month, maximum." Bruce chuckled. "Clint needs the rest anyway."

Tony snorted and patted Clint's back as he sat down on the couch. "Yeah, and Pepper bought like fifty different outfits for him to wear. She'd be sad if she didn't get to try them on her. And looking at this, I'm going to be crushed if I don't get to see him in them. I actually got a call yesterday." Steve raised an eyebrow at him. "From a baby modeling company. They asked if Clint could model for their special issue."

Bruce frowned. "Clint is going to hate that. I hope you said no."

Tony turned to scowl at him. "Of course I said no. I'm not sharing this. This is way too precious." He gently lifted Clint from his shoulder and held him so he could examine Clint. "Yeah." He sighed, bringing him back closer to his chest. Clint was pleasantly warm against him, and Tony could feel his heart beating. "This is way too precious."