A/N: I got the idea from a post on Tumblr - and for some reason cannot for the life of me get the URL to go in here to share it, so sorry about that - and liked the idea so much I couldn't help writing a fic for it during my music theory class.

"It's your turn to put him to bed," Maria murmured in Steve's ear as she passed, glancing back over her shoulder at Jack before opening the file in her hand. Jack was standing on the back of the sofa in his pajamas, making loud roaring sounds interspersed with rattling coughs. Steve grinned and watched Maria's retreating figure for a moment before heading into the living room to catch his son up in his arms. At eight, Jack was in that in-between stage during which he at times showed signs of maturity and at times was every bit a little boy. His shriek as Steve lifted him became a short cough and Steve tried to hide his concern. Jack didn't like being fussed over any more than Steve had at his age.

"What was all that racket?" he asked. The little boy grinned and raised his arms menacingly.

"I'm being Uncle Bruce when he's mad," he explained. Steve chuckled. When he'd been a kid – admittedly nearly a century ago, but still – he'd read books and tried to play sports. He and the other little boys had pretended to be lions, monkeys, dinosaurs – never giant green alter-egos of gamma-radiation scientists.

"Very convincing. Time for bed, Hulk." He set Jack down in the bathroom doorway and managed to keep the child focused long enough to get his teeth brushed. He inspected the teeth, pronounced them clean, and told his son to give Mommy a kiss goodnight. Jack grinned up at him and then took off at a run. Steve followed at a more leisurely pace, long legs easily keeping Jack in sight. He entered the study just in time to see Jack crash into Maria, little arms flying around her neck. He had to pause to cough as she lifted him into her lap and from his place in the doorway Steve could see how winded the little boy was from just that short exertion. He buried the twist of guilt at the observation and kept a smile on his face as Maria sent Jack back in his direction, meeting her eyes with a wink as their son reached him.

"I'm not sleepy, Daddy." He was still panting, thin chest heaving as his lungs tried to take in enough oxygen to compensate for the sudden burst of exertion he'd put out. Steve's hand completely swallowed Jack's as he led him back to his bedroom.

"You never are," he agreed. "It's bedtime whether you're sleepy or not." Jack complained, but a look from Steve stopped the whining. He climbed into bed, curled up with his stuffed giraffe – which, according to Jack, was never really a giraffe but alternated between various extra-terrestrial species depending on what stories Thor had been telling most recently – and then shifted to wrap his arms around Steve's neck as the man whispered goodnight. Steve plugged in the night-light on his way out and reached for the door handle.

"Daddy?" It was almost a nightly ritual at this point, Jack coming up with a question just as Steve reached the doorway. He turned back and took a couple of steps in Jack's direction. "If JARVIS is a computer, how come he gets to boss me?" Steve chuckled.

"Because I told Uncle Tony to program him that way. You might be smarter, but JARVIS has more sense than you still." Jack pulled a face at that and Steve turned away again. JARVIS was perhaps the most convenient thing to have around when it came to having a son. Programmed correctly, the AI could keep a reasonably safe eye on Jack, leaving them free when they needed to be. Steve preferred not to leave Jack with only JARVIS for supervision, but in a pinch it was effective.

"Daddy?" Right in the doorway again. The kid had it down to a science at this point. "Tell me about Thor's brother and the aliens."

"You've heard that story from every one of us about five times," Steve reminded him. Jack nodded, unperturbed.

"It's good. Please?" He dragged out the e into a wheedling plea, and Steve could only hesitate a moment before going back to his son's bedside.

"Alright, but you're going straight to sleep after this, hm?" Jack nodded compliantly and curled up again, giraffe under one arm and little eyes focused intently on Steve's face as the man launched into a modified recounting of the Chitauri attack and the battle in Manhattan. About the time he was telling about Selvig shutting down the Tesseract, Jack's eyelids had quit fluttering and he'd relaxed his grip on the blankets and the stuffed animal. Steve let his voice drop, whispered something about the good guys winning, and then silently walked to the door.

"Daddy?" Of course it was just as he reached the doorway. Steve paused and turned back. He'd thought Jack was asleep. Two and a half long steps carried him back to the bedside. Dark eyes so like Maria's stared up from Jack's thin face for a moment before they slid shut again. "When I grow up I'm going to be just like you." At the sleepy mumble, Steve had to force himself to keep breathing. He dropped to sit on the edge of the bed, laying one hand on the eight-year-old's forehead. The little trusting smile on Jack's face sent a dart of pain through Steve's heart. He bent to kiss his son's head and then stared for a small, silent eternity at the thin face before rising and leaving the room.

He'd never actually expected a son. Fatherhood had never even occurred to him. Perhaps that was because of his own dad – that had never been the sort of experience Steve would want to replicate. The man had died when Steve had been only five, but his ghost had lived on. He hadn't actually been any kind of overtly evil monster, but his presence had left a shadow that his death couldn't remove. Steve had grown up seeing the remnant of the man's influence in his mother's eyes, in the way she'd carefully raised him to be everything his father hadn't… Then again, maybe the idea had never occurred to him simply because no woman had ever looked twice at him. He'd been so scrawny and sickly that the army wouldn't consider him, and he'd expected, though he'd never admitted it, to become an old unmarried professor. And then there had been Professor Erskine and Operation: Rebirth and the serum and the plane crash…

And then somehow there had been Maria. Smart, professional, formidable, and absolutely beautiful. Probably he'd been obtuse not to expect Jack after Maria had become a part of his life, but… He still remembered the day she'd told him, so calmly and rationally, as if she were mentioning a new rookie on a strike team. That was the way she handled situations that she didn't feel in control of – she went into her professional mode, handled the facts, ignored the rest. She'd done that with him for months; it had been a bit off-putting, but he'd been stubborn. He couldn't blame her for not knowing how to handle the idea of a child. He didn't know how to handle the idea of a child. She'd said it so calmly. It had taken a moment for the words to sink in, and then he'd only been able to stare, disbelieving, across the room at her.

"There's – you're trying to tell me we're having a baby?" She'd laughed then, almost giddily, and after that he'd been across the room in a second, swinging her up in his arms, trying to kiss her through their laughter. It had been complicated, of course – it had been complicated enough getting married in the first place, but that had been patently necessary. He'd thought he might just go crazy if he had to wait any longer. Maria had reminded him that times had changed, that she was all his whether they had any kind of legal documentation or not, but he hadn't gotten over the culture shock yet, perhaps, because he couldn't do it. "My mother taught me to be a gentleman, ma'am," he'd told her, not quite sure how to explain it. "Taught me to commit. She said if a thing was worth doing, it was worth doing right, and you're more worth treating right than anyone I've ever met." He didn't think she'd really minded all that much, because he didn't think he'd ever seen her smile quite like that until the moment she let him slide a ring onto her finger. Fury had looked both amused and skeptical at the entire thing, but there had been no doubts in Steve's mind. And a baby – well, they'd handled revolutions, crime rings, alien attacks, and political coups. He figured they could probably handle an infant. Maria had insisted she was fully capable of working, and he'd had to agree that she was. He'd persuaded her to restrict her work to the helicarrier, though. She'd humoured him with some good-natured rolling of her eyes. He thought she was secretly a little pleased that someone cared enough to worry about her. And then Jack had been born, and Steve hadn't known he could be that happy. But there had been complications right from the start.

Maria noticed the look on his face right away as he entered the room. She closed the file she'd been studying and patted the sofa beside her invitingly.

"What's wrong, Captain?" He settled beside her, slid one arm around her shoulders, and met her eyes for just a moment before looking off blindly at the wall.

"Jack… he wants to be just like me…" His voice cracked on the last word and he drew a long breath. His son would never be just like him. The little boy was one of the bravest, most tenacious people Steve knew, but Steve knew better than anyone that all the bravery and tenacity in the world couldn't persuade a body to do things if it simply wasn't able. He hadn't thought about it at all before Jack's birth. He didn't know why, but the idea had never crossed his mind, this thought that his son might be just like him – just like the Steve Rogers who hadn't been able to play a full game of baseball as a kid, hadn't been able to run because his throat closed up, hadn't been able to keep up with the other boys because his muscles and bones couldn't support him long enough… Maria's head dropped against his shoulder.

"He will be. He'll be brave and stubborn and courteous and responsible." She twisted her neck a little to look up at him. "He does have the best dad in the world, remember." Steve couldn't quite smile back. They'd nearly lost Jack right there in the hospital the night he was born. Maria had pulled through the entire labour and delivery like the woman she was – unstoppable and fearless. The tiny infant she'd brought into the world, though, seemed to be fighting with everything in him simply to keep breathing. He'd been in the hospital for weeks. The doctors had said he had a decent shot at making it, but there had been doubt in their eyes. Steve had tried to quell the tiny voice that whispered his son might not live to see outside the hospital. He'd told Maria everything would be okay.

"You know that's not what he's thinking," he said. "Boys his age don't care about courtesy." He was Steve Rogers, Captain America, an international celebrity, possibly the strongest man in the world, almost indestructible, a legend who had helped save the world numerous times. The father of a little boy who would never be able to fulfill even the minimal physical requirements of a SHIELD agent. He'd been turned into a super-soldier, but that hadn't changed his genes – hadn't changed the genetics he passed down to Jack. Didn't change the fact that the strongest man in the world had given his son brittle bones and fragile muscles that forced him to wear braces. Lungs that couldn't quite work hard enough. Airways that closed off if he exerted himself. A heart that couldn't pump the way it should. And there was nothing Steve could do about it. Maria's fingers slid between his.

"There are a lot of things more important than muscle," she reminded him. "You've told me that as long as I've known you." That was true. He didn't like being seen as simply a lot of muscle and superhuman endurance and reflexes. He wasn't comfortable with the attention and adulation. He sighed.

"He still believes in the impossible. He doesn't know about disappointment and disillusionment." Steve swallowed and tightened his fingers around Maria's almost without noticing. "What happens when he realizes he can't be like me?" he whispered. That wasn't the real question. His eyes slid shut painfully for a moment. "I mean – when he realizes he is like me…" Maria's hand on his cheek made Steve open his eyes again. She shifted a little to face him without letting go of his hand.

"Steve, who you are isn't determined by your body. I wouldn't want any other man's son and I wouldn't want any other man to raise my son. He is like you. I wouldn't trade that for the world." Steve chuckled, hating the way the sound came out shaky.

"You're the strong one. I'm the science experiment." That came out sounding more bitter than he'd intended. He sighed. "I'm sorry."

"You were strong before you ever joined that experiment group. What are you apologizing for?" She held his eyes for a long moment. "Is this about Jack or you? Are you sure you're not just having a crisis because his health isn't something you can jump in and save with that shield of yours?" Steve closed his eyes again and let his head drop to rest his cheek against Maria's hair.

"It's not about me. Or it is. It's – I'm the only reason he'll never be what he wants to be." Maria drew back a little, forcing Steve to lift his head.

"That's not true and certainly not fair." She sounded almost angry. "Where's the Steve Rogers who applied a hundred times to the army even though they told him he'd never be a soldier? Where's the Steve Rogers who's been doing impossible things since World War II? You did all that because you were too stubborn to give up when they told you to. Don't you dare consign your son to his physical limitations." He blinked. It was true, though he hadn't thought about it. Maria's dark eyes flashed at him for a moment longer, and then she sighed and dropped her head against his chest. "You're his hero, Steve. You'll always be his hero. He's your fault, yeah – at least half your fault, anyway. That's a good thing. Quit blaming yourself for his weaknesses and take a look at what an incredible little boy you made, hm?" Steve pulled her a little closer, blinked back the sudden sting of tears in his eyes and pressed a kiss to the top of his wife's head.

"I think his mother has a lot to do with how incredible he is," he murmured. Maria turned her head to meet his kiss.

"Cap! Hey check this out –" Tony's voice from the doorway effectively broke the ambiance of the moment. Steve drew back just far enough to see Maria rolling her eyes. He grinned, dropped another quick kiss on her mouth, and then turned to look at Tony. The billionaire had paused inside the doorway, smirking. "Hope I'm not interrupting anything. You two weren't, ah, having a moment or anything were you?" His voice assured Steve that Tony was sure he was interrupting and was more amused than embarrassed by the fact. He raised one eyebrow questioningly at Stark. Maria was less patient. She whipped out a handgun from somewhere that Steve hadn't noticed and waved it in Tony's direction.

"This better be good, Stark. You might own the Tower, but I'm not above shooting you anyway." Tony took a couple of steps, leapt over a coffee table, and dropped into the armchair across from the couple.

"It's good. Check this out." He produced a jumbled pile of wires and metal strips and then waited expectantly, eyes on their faces, leaning forward. Steve blinked.

''That's – uh – what is it?" Tony stared disbelievingly, then let out a quick exasperated breath and set to work untangling the mess of scraps in his lap. It still didn't look particularly impressive or recognizable. After waiting another moment and getting no reaction, Tony scooted forward another inch on the edge of the chair.

"Look – these wires connect to the muscles of his calves. These ones attach to his thighs and these run up his spine. Electrical signals stimulate his muscles and nerves. These –" he lifted one of the shiny metal strips – "are lightweight supports." Steve and Maria both stared for a moment longer, and then Tony dropped the contraption back into his lap and flopped back against the chair. "They're like the braces he has now, but they're lighter, sleeker, and they'll actually do his muscles some good." Maria stared skeptically for a moment, then set down her gun and reached out to pick up one of the metal plates, her fingers tracing its smooth edges.

"Alright, Stark – I'm hooked. Explain how this works." Looking pleased at her interest, Tony sat up again and dove headfirst into a complicated technical explanation of which Steve understood only one word in five. Maria turned back toward him, eyes sparkling. "See what I mean?" she murmured under Tony's enthusiastic monologue. "With a dad like you and an uncle like Tony, I have a feeling Jack can do whatever he wants." She grinned and leaned up to kiss him quickly. "After all – he's Captain America's son."