Slight spoilers for Captain America 2. Begins where the movie ends. I do not own the Avengers.
After she leaves Steve at the graveyard, Natasha Romanoff climbs into the discreet black car. And that is when the shaking starts.
It isn't the type of shaking that happens when she cries- no, this is much more precise, and therefore much more scary. Each part of her body tremors, shakes in its place, and. She. Can't. Breathe. Her throat is closed, her brain is switching between overcharged and not working, and Natasha Romanoff, super spy, secret assassin, Black Widow, can't do anything.
It is the slightly open window that saves her.
It is her coughs, desperate and gasping for air, that alert Steve to what is going on. Without warning, he shoves Bucky's files into Sam's hands and runs, following the all-too-familiar sounds of Nat trying to breathe. He knew that something was up, knew it when he saw her clenched jaw and tight breathing. He knew she would fight it- she always did.
When Steve gets there, Natasha is vomiting, her eyes streaming with tears that she had fought so hard to not let him see. He opens the door forcefully, but his hands are gentle as he rotates Natasha 90 degrees, so her face is towards the wind. His fingers are soft as he wipes the tears away, her body shaking as she hyperventilates. Her coughs grow more urgent as she throws up again, her body and mind retaliating against all the stress she has been put through.
Steve doesn't have to be told that this is her first panic attack. He can see it in her eyes, usually guarded with an infinite amount of secrets, now full of fear. As Sam appears behind him, Steve motions him to bring a car around. He never wraps his arms around Natasha, knowing what the enclosed feeling will do. Instead, he simply stays, a lone hand on her back as she struggles for air and for calm.
It is not a minute later that Sam pulls up and Steve directs him to Stark Tower, handing over his passcard.
"Go up to floor 35, and tell Clint exactly where we are. Clint's going to be here soon, okay? Then go to 40, and explain to Tony and Bruce. Shhhh, Nat, I'm right here. Tell them to come here with transport now." Steve explains quickly, then turns back to his best friend, still heaving in the driver's seat of a SHIELD car. His hands find their way into her hair, pulling it away from her face as he murmurs gently. He knows that panic attacks can go on for quite a while, and intends to stay as long as needed.
Within ten minutes, Clint has arrived, still in sweatpants and a grey t-shirt. He rushes over to Natasha, his movements powerful and quick, but when his fingers meet her tears, they are quiet. He, too, doesn't press for information; just presses kisses to her temples. When her chest begins to heave again, and the coughs become more rampant, he places a strong hand on her forehead so she doesn't slam it against the steering wheel as she throws up again. He murmurs in her ear soft words that seem to make the fear in her eyes dissipate, but do nothing for her shaking body and the struggle to breathe.
In half an hour, Tony is there, and Natasha has stopped vomiting, but the tears and the breathing still pose an issue. She is coughing rapidly, her breaths heavy and unnatural, as both Clint and Steve run hands through her hair. Tony is surprisingly gentle, just guiding her by the hand into the back of the car. He mumbles something that only Steve's oversensitive ears can hear.
"I know you don't want to be in the spotlight right now, so Pepper and everyone else are in another car. It's going to be me, Clint, Steve, and you. Are you okay with that?" She nods slightly. "Okay. We're going to get you to lie down now." If Steve wasn't so worried, he would wonder why- and how- Tony was so kind and understanding, but everyone had their ways of dealing with stress. It wasn't impossible that Tony hadn't broken down once.
Natasha's head rests in Clint's lap, with Steve sitting on the floor next to them. She is no longer crying, but her throat is still closed up and the shaking hasn't stop. It feels like it will never stop. Clint carries her upstairs, and it is a sign of her pure fear that she doesn't protest.
The rest of the day, coughs can still be heard from their room. Pepper is worried sick, trying to find different remedies before Tony tells her that nothing exists to stop a panic attack. Bruce comes in occasionally, supposedly to check for a fever but mainly to make sure that Natasha is okay, because he understands more than anyone how terrifying it is. Fury calls Clint's phone five times before giving up and calling Tony, who yells at him quite a bit when he realizes that the startling beeps of the cell phone woke Nat from her nap. Steve paces around quite a bit and nearly bites through his lower lip with worry.
Around nine the next morning, Natasha slowly emerges from her bedroom, eyes red and throat ragged, with Clint's arm holding her steady by the waist. She still coughs occasionally, and her slight frame shakes with every step, but everybody in the tower understands why, and nobody will question it. As she wanders into the living room with a cough, she notices a small pile of assorted objects on the coffee table, among them a pint of ice cream, cough drops, and a note from her other housemates.
Nat,
We just want you to know that we've all been there. None of us are going to think of you any differently. It's okay to be taken care of sometimes.
And even though she shakes and coughs as she does so, when Tony, Bruce, and Steve walk into the room slowly, each with a worried expression on their face, she smiles.