Steve:
You stay with him...always. (REFERENCE ALERT)
You watch movies, and you make him soup, too.
Tony:
SO. MUCH. COMPLAINING.
Thor:
Since when does a god get sick? I have no idea. If he does, you'd keep him company and cancel all events you were going to do. You'd teach him how to do Earth tech.
Clint:
Like Tony, he complains a lot. But you hush him up with his favorite tv show and soup. And he says that you help him too, because he'd die of boredom.
Bruce:
He'd be wanting to do science, so you'd help him to the lab. He'd be doing sciency stuff on the computer, and you'd be doing experiments.
Natasha:
She hardly gets sick. I mean, she's a tough assassin. But when she does, she wants you and her to nap all day. And that's fine with you.
Loki:
Like Thor, I don't think he gets sick. But if he does, you would resume your book club you both created.
Bucky:
You would watch Supernatural or some other tv show with him and chant the intro of Supernatural...
Pietro:
He actually doesn't move when he's sick, he's just face down on the bed. You rub his back and make him eat something. Then he's back to being a miserable human on the bed.
Wanda:
You'd do the same thing when you're sick. You'd look at recipes and nap all day. Maybe you'll watch some tv.