Steve had been warned by the others already, but when he entered the communal living room in the Tower, he couldn't help gaping for a moment. The kid was really, really cute.
He had always liked children, and before this whole frozen-in-the-ice-for-70-years mess had happened, he had liked to imagine that one day he would marry and have his own. He certainly wasn't the type to take out the baby talk and cheek pinching when around children, though. Children deserved to be treated with kindness and warmth, and squeezing them and shrieking into their face had never seemed particularly kind or considerate to him. Right this moment, however, he could feel his fingers twitch involuntarily. Those little rosy cheeks just looked so... pinchable. And the hair! He had expected the child to be as dark-haired as his adult counterpart, but the child sitting on the sofa was basically blond. Leave it to Tony to defy all expectations.
While he had been busy standing in the doorway, staring at their newly acquired 5-year-old, said 5-year-old had become aware of his presence. Huge, round, dark eyes turned towards him, focusing on him completely. A moment later, the boy hopped off the sofa and scuttled over to where Steve was standing. He unceremoniously latched on to Steve's trouser leg, staring up at him with an intense look in his eyes.
“You're Captain America,” he said, his voice filled with awe. “Daddy found you!”
Steve couldn't help but smile down at the boy. He still remembered his and (adult) Tony's first meeting very well, Tony being completely unimpressed with his everything and constantly blabbering on about things that Steve didn't understand (but having the vague feeling that he was being insulted). This Tony couldn't be more different, seeming to be extremely awed that he got to meet Captain America.
He gave in to his impulse and bent down, carefully stroking Tony's soft, fair hair. Like a cat, the boy immediately leant into the touch, enjoying the attention.
This must be Tony all right, Steve thought to himself, still hogging the attention wherever he goes.
“That I am,” he answered instead, “And who might you be?”
“Anthony Edward Stark,” Tony replied with a huge smile on his face, “But you can call me Tony!”
“Well, Tony, it's an honour to meet you,” Steve responded seriously. “People know me as Captain America, but you can call me Steve.”
The fact that Captain America had just allowed Tony to call him by his given name seemed to leave Tony speechless for a moment. When he gathered himself, his face grew serious, though.
“But, if you're here, where's Daddy?” Tony inquired. “He promised to introduce me to you!”
He stared up at Steve with his intense eyes and a slight pout, and Steve felt his heart pound a little faster. How to explain to a five-year-old that he wasn't really five years old, but had been de-aged by magic, and that his parents had been dead for years?
“I'm really sorry about that, but your father has been called away for something very, very important, and can't be here with us,” Steve tried to explain (badly, he thought). “But I really wanted to meet you, so I came alone. I'll be staying with you until he returns?”
Steve had only said that in a bout of slight panic, but Tony's face lit up like Christmas had come early. He immediately started babbling about all the amazing things he had to show to the one and only Captain America, while Steve finally chanced a glance away from Tony, towards the rest of his teammates (minus Thor). All of them were wearing various shades of the same 'I am concerned, yet amused' expression on their faces. Steve itched to ask them if they already knew what exactly had happened, and if they had any clues how they should deal with this (you leave them alone for a short while once, and this happens, really now). Was it a curse? Could it be reversed? What should they do with Tony? But with all of Tony's attention centred on him, Steve didn't dare to ask.
“Can we go home now?” Tony finally asked. “I want to go home.”
Steve startled. He had been so overwhelmed by this unprecedented development that he hadn't really thought about how they should deal with these new circumstances. Obviously, the Tower was not the place Tony had grown up in. And he probably had never seen the modern, sleek design and technology he was currently surrounded with. It was a surprise Tony wasn't panicking completely, seeing as he was in a place he didn't know with people he had never met. Honestly, thinking about it, Steve felt uncomfortably close to kidnapping, even though he rationally knew that Tony really was a full-grown adult that had his own multi-billion dollar company.
He heard one of his teammates (badly) suppress a snicker. Oh, so that was it. They had probably been holding out until Captain America came back, only to shove the child into his care and let him deal with all the difficult questions. Not that this changed how they usually dealt with anything related to Tony.
Probably noticing his internal panicking, J.A.R.V.I.S smoothly inserted himself in the conversation.
“Young sir, if I may interrupt?” he asked.
Tony's eyes grew big.
“Jarvis?” he piped. “Jarvis, where are youuuu, I wanna go home.”
“I am speaking on the phone, young sir,” J.A.R.V.I.S answered in his usual calm and collected tone. Apparently, Tony had done an excellent job, making the A.I. so similar to the actual Jarvis that his younger version didn't even notice the difference. “I am terribly sorry, but as Mr. Rogers has mentioned already, sir had to leave due to urgent business, and I fear you won't be allowed to return home for the time being. It is of utmost importance for your own safety. Mr. Rogers and his team will stay with you, however, until you are allowed to return home. I won't be able to stay with you, I am afraid, but you may call me at any time, young sir.”
Dear Lord, Steve thought, what were you thinking, J.A.R.V.I.S. This is never going to work. Tony will never accept such a flimsy excuse.
Tony made an unhappy face, but then, to Steve's astonishment, said: “Stupid Daddy, he never tells me anything, and he always breaks his promises! I'm going to stay with Steve, and I'm never going back!”
With that, he latched on to Steve's leg once more, and pulled on his trousers until Steve lifted him and cradled him in his arms. Tony immediately put his arms around Steve's neck and burrowed his face in Steve's chest, clinging so forcefully that it seemed he planned to never let go again.
After a moment, Steve could feel Tony starting to shake, and heard his breath hitch. Tony had reached his limit, it seemed. He automatically started to sway back and forth a little, rubbing Tony's back, simultaneously chastising Clint with a glare. The archer had already opened his mouth, no doubt to spout something rude, as he usually liked to do with Tony. Seeing that Cap really didn't approve, Clint closed his mouth, and imitated Kid Tony's pouty face instead (he was suspiciously good at that).
Steve only rolled his eyes and turned to leave the living room. He could deal with his team and this whole mess of a situation later, but first he had to make sure that Tony was okay and taken care of.
“Come, we'll get you set up in a room, Tony,” he said softly.
Tony, his face still squished to Steve's chest, shook his head.
“Want to stay with you,” he mumbled, and clung to Steve even harder (not that Steve was bothered by that in the least, it was so much better than getting strangled by a Chitauri or a Hydra goon).
Steve considered. Honestly, he could use some kind of emergency protocol about how to deal with suddenly de-aged Avengers right about now. Why was there no such protocol? That was a gross oversight, he decided, and needed to be addressed at the next meeting.
“How about... we go to my room, and I will show you my shield before you lie down and take a nap?” he suggested, “I promise I will stay with you the whole time.”
Tony abruptly lifted his head to look at Steve with large, shocked eyes.
“Can I touch it?” he asked breathlessly (deliberately ignoring the fact that Steve had also suggested he take a nap – some things apparently never changed).
“Yes, you can touch it,” Steve chuckled, “if you're careful, you can even hold it.”
Tony only stared back with an expression of absolute reverence.
“So... that went surprisingly well?” Bruce said, one eyebrow raised, when the Captain and Tiny Tony (how creative, Clint) had left the room.
Clint started laughing.
“Cap is totally motherhenning Stark! And he has absolutely no defence against that pouting face!” he cackled. Natasha rolled her eyes.
“I've told you before, in case of Stark, get Cap,” she said with a smirk.
“A flawless plan,” Bruce agreed with her. “We should stick to it.”
They all agreed completely to do just that.