AN: So, to clear some things up, Natasha is dating Clint and in a queerplatonic relationship with Captain, who is dating Clint as well. :)
I do not own the Avengers.
Natasha Romanoff had a powerful immune system. Genetically engineered to fight most illness, coupled with a ridiculous amount of exercise, strictly healthy diet, strong stomach, and exposure to most diseases, she never got sick. When Tony had the flu for a week and a half and ended up spreading it to the rest of the tower? She brought water bottles and thermometers. When Clint started vomiting in the middle of the night? She kissed his temples and rubbed his stomach. When super soldier Steve Rogers had a 103.7 fever for five days? She kept ice on his forehead and stayed with him the entire time. When it was cold season and everyone around her didn't stop sniffling? She bought extra tissues. Even when Thor had brought back some Asgardian version of the common cold and the entire tower was sneezing for a month? She was fine. When Steve's asthma flared up during said cold and he literally couldn't breathe for an hour? She was the one to buy the inhalers. When allergy season came around? Nobody even expected her to sniffle.
So, when it's the middle of June and nobody has been sick in weeks, nobody expects Steve to walk downstairs to the common area, announcing that they had to cancel their picnic. "Nat's sick. It's not that bad- just congestion and a lot of coughing- but since she's never sick, I'd rather we stay here." The room quiets enough to hear a few ragged coughs from Nat, Clint, and Steve's shared room (well, floor). Tony begins to laugh as Pepper starts returning food to the fridge.
"It's about damn time she gets sick." He jokes, but the worry in his eyes is obvious. Everyone begins nervously talking again before Natasha wanders into the crowd. Her skin is pale, almost translucent, except for her flushed cheeks. Her hair is in knots, and she coughs into her hand as she walks slowly. Both Steve and Clint wrap an arm around her, Clint's on her waist and Steve's around her shoulders. An awkward silence fills the air as the three stand there, marveling at the sheer event of Natasha becoming ill.
Natasha somehow squirms her way out of her boyfriend and her queerplatonic partner to slowly get a glass of orange juice out of the fridge, drinking it slowly as the conversation starts up again. Tony is gentle but firm when he turns to her, compassion cleverly hidden. "You better stay the hell away from us, cause anything that can bring you down will probably kill me." Natasha's laugh turns into a cough and she takes slow, deep breaths.
"Shut up, Stark. It's nothing big, nothing to cancel plans over." Before she can even finish her sentence, both Clint and Steve are shaking their heads.
"Tasha, I'm pretty sure this isn't small given the fact that you never get sick. So if you have a fever," Clint's hand was resting on her forehead now, "You probably need to lay low for a while. At least we know now that you're not superhuman." He kissed the top of her head lightly as she took another swig of orange juice. Bruce had already excused himself to go retrieve his medical supplies, and Tony was hovering, trying to see what he could do. As Natasha began to cough again, her small frame shaking, he mumbled something about getting breakfast for Clint and Steve and slipped out. Pepper was busy making soup already and pulling various medicines out of the cabinet before Clint shook his head.
"Medicine will only make it worse. Don't bother." He says gently as Steve starts putting ice packs into the freezer to harden. Natasha rolls her eyes at their antics and stumbles to the TV, her impeccable balance thrown off by the illness and impending headache. Just as she is about to turn it on, Clint comes around behind her and takes the remote.
"TV will give you a headache. We're going to sleep instead." Clint takes Natasha's hand in his and Steve's hand in the other, the latter brushing his lips over the worry lines on Clint's forehead. Natasha is finally coerced into lying down, her congestion worsening as she endures a fitful sleep.
"Clint, I know that you're worried about her, and I understand that. But Tony was right- Tasha never gets sick. I would feel a lot more comfortable if you would let me take care of her, because I really can't handle both of you being ill." Steve Rogers whispers these things as he presses kisses to Clint's lips, murmuring the words gently as if he will get a kinder response. "I'm less likely to become infected, and you know Fury will get angry if both of you are down." The archer sighs, knowing that his boyfriend is right, but also knowing that he is the only one that really knows how Natasha functions under these conditions.
"Fine," he mumbles against Steve's lips, "but if you start to feel even a little ill, I'm taking over." Steve laughs, and the unexpected noise amongst their quiet whispers makes Natasha sit straight up in bed, pulling the gun out from under her pillow out of sheer instinct. She coughs and shakes as she does so, but her eyes are cold and calculating before she realizes she is aiming at Captain America.
"Calm down darlin', I'd really like to see you get better." He laughs uneasily, not liking the way her arms are shaking, and gently pries the gun out of her hands. "I'm sorry I woke you. How about we go back to sleep?" He slips into the bed easily, pulling her head into his shoulder and wrapping his arms around her waist, one hand resting on her back, tangled in her long hair. Clint laughs, pressing a kiss to both of their heads before slipping out of the room. Natasha pulls Steve closer, nestling her head against his and coughing lightly. Steve notes that she is extremely clingy when she is ill- her hands tightening around his shoulders, her legs tangling in between his- and presses a kiss into her hair. She falls asleep clinging to him, his grip on her waist never loosening.