It starts off so slowly that no one notices at first. Gradual effects and gradual symptoms are masked by the sheer taxing physicality of being an Avenger, building and building like a canister under pressure until his body can’t take it anymore.
But out of all the Avengers, they don’t expect Steve to fall first.
Tony curls his legs under his arms and watches the super soldier with nearly unblinking eyes. All the team watches over him in shifts, but they know not to disturb the unfaltering vigil of Tony Stark. Natasha has claimed the other chair, and seems to spend her time critically studying him, just as much as she critically studies the blonde super soldier who remains asleep in his hospital bed.
"How is he?" Clint lingers in the doorway with an expression that is torn between dedicated concern and a clear desire to retreat back somewhere more comfortable. He is as terrified as all of them and just as knowledgeable that no one understands super soldier physiology to understand how to help him without experimentation.
"Well, he won’t be playing Ultimate Frisbee anytime soon," Tony tries to joke, tapping the Shield with his knuckles and a shiteating grin that doesn’t quite reaches his eyes, "But I’m starting to think Stevie here just wanted a day off."
Clint narrows his eyes for a second, and feels a barb on the end of his tongue, but notices quickly enough that Stark’s heart isn’t in his questionable taste in jokes, and Natasha is watching him in concern.
"He’s severely malnourished," Natasha offers with a grim line to her mouth, "Protein-energy malnourished, deficient in Everything from Vitamin A-Z, Calcium, Folic Acid, Iodine. They started Intravenous therapy a few hours ago; electrolytes, nutrients and water- to combat his early stage of dehydration."
Tony slumped in his seat as Clint swore.
"This isn’t your fault Stark," She suddenly turned towards Tony with finality in her tone.
"He lived in my house," Tony cut back viciously, "What the hell kind of host am I, if my guest is in hospital for malnutrition. I should have noticed."
It started off so gradually that no one could have noticed. Steve’s gentle smiles as he slept off after a mission, hiding his fatigue and the incessant pain in his joints. The natural paleness of his skin hiding the pallor in his face, poor concentration hidden by the distractive nature of life in Stark Tower, lightheadedness explained as PTSD, Breathing troubles excused by anxiety attacks- because Captain Steve Rogers was a super soldier and couldn't possibly get sick-
And then his hair started falling out.
Natasha met his narrowed rebellious eyes with her own, leaving Clint to stand in the doorway with a tightness to his mouth as he bit back sarcastic defensive words.
"We all should have noticed."
The announcement drew both their attention, severing the intensity back down to a concerned ambience.
Tony sighed and ran his hands down his face with a tired expression, “I built JARVIS. I programmed him to recognize symptoms and to report them back to me if he decided that they were significant. I programmed him to see Captain America as invincible- because- he’s a super soldier, he’s Captain America- He shouldn’t be here.”
"We all thought the same thing," Natasha reminded him, levelling her sharp eyes at him, "You are not responsible."
Tony sighed again, and leant back in his chair.
"Then who the hell is?"
"No one," Natasha leant forward, "We don’t know enough about his physiology. No one could have anticipated this. We know more now, and we can stop this from happening again. No one knew that his physiology came with such dramatic drawbacks. Now we do. Now we can protect him better."
"So what now?" Clint glanced between the two, and crossed his arms with a frown, "How the hell did this even happen and where the hell do we go from here?"
"His metabolism runs roughly four times faster than the average person," Tony announced with a frown, "He needs about 8,000 calories on a daily basis to ensure he stays functional. Take into account his activity level and size, he needs about 14,000 calories for his metabolic requirements."
Clint and Natasha exchanged looks.
"We knew it was high, but, hell-" Clint swore again, "He wasn’t eating enough calories? I mean, he was always snacking-"
"That’s not the problem, plenty of calories, empty calories," Tony rubbed at his eyes again, "He wasn’t meeting nutritional goals. SHIELD told him to eat calories, but didn’t give him any information on how to change his diet to a super soldier friendly eating plan. Did you know that he needs 50mg of Iron every day, because of his metabolism? I didn’t, and I’m sure as hell that Steve didn’t know. That amount would poison the average human, but for Steve? We kept giving him energy bars, loaded with sugar and salt because glucose is good for energy kicks right? We probably would have been better off giving him canisters of sugar to eat.'
"Holy shit," Clint sighed, and massaged his temples, "How long?"
"Bruce thinks his body’s been in starvation mode since we thawed him," Tony frowned, "Did no one actually wonder ‘oh golly gosh maybe the decades of being frozen might have caused some problems on his metabolism?’ No, it seems like every goddamn SHIELD agent decided he was brought back from the dead by some hippie magicks and Coulson’s fanboyish strength of will!"
Natasha shifted in her chair, and considered Steve’s pale face in concentration, “When he wakes up, we have a strict regime for him to follow. Stark persuaded a nutritionist to work with the medical staff to ensure that Rogers meets all his nutritional requirements in the future. He has a long road of fortified food, supplements and high quality protein ahead of him.”
"He’ll be okay." Clint relaxed, and watched the slumbering soldier with a look of utmost relief, letting a fond smile reach the corners of his mouth.
"So, Who wants to tell Rapunzel about the loss of his luscious locks?" Stark grinned back, in a cocky confrontational tone, ruined by the faction of his fingers caressing the edge of the shield by his side, "C’mon, I’m telling him that he’s benched for at least a month, I’m sure as hell not telling Captain tight pants to thank the heavens that his cowl will hide his bald spots. Old men tend to be self conscious about that kind of thing…"
"You’d know all about that, now, wouldn’t you Stark," Clint bit back, as Tony recoiled in mock anger and started a sarcastic pop-culture spiel.
Maybe they hadn’t noticed at first, but in the end it is a sobering reminder that sometimes things happen that doesn’t come with a cartoonish evil villain to destroy and crush, but sometimes comes in the form of things that take time to heal and change.
It is a reminder that while even Heroes can fall, they always have each other to watch their backs while they stand back up again, even stronger than before.