Steve got food poisoning at a bar he went with Natasha and she tries to make him feel better.
This is really fluff so enjoy :)

Steve woke up in the morning with Nat in his arms, he stayed still for a couple of minutes just to admire her, but then he felt the urge to vomit.

He ran to the bathroom and vomited inside the toilet.
Natasha woke up by him running and decided to follow him, quietly so he wouldn't hear.

"Steve are you okay?" Nat asked with worry in her eyes "yeah yeah I just felt the urge to vomit it's probably nothing don't worry" Steve atood up and went to the sink to wash his mouth. "you know, you might have morning sickness, maybe you're pregnant!" nataha said sarcastically and Steve laughed at the sentence. "I have a small mission later, it's not big, just a couple of hours." Natasha said as She came up behind him and wrapped her arms around his waist. "okay, be careful" Steve said with love "I will" she said and pecked his neck.

Natasha was out, and Steve felt a little better after she made him tea, but he still didn't knew what caused his sickness because he knew the couldn't get sick, but then he remembered that two nights earlier Natasha dragged him to this bar downtown, and the food didn't seem so fancy, but at first sight he didn't care, because he used to eat much worse food at the 40', so he took some mozzarella sticks and a cheeseburger. He probably got food poisoning.

As he remembered he felt gross felling down his throat, probably vomiting again, so he ran back to the bathroom to vomit. Until Natasha got home he vomited at least 3 times.

Natasha got back from the mission exhausted, she had to run a lot, but she didn't need to fight though, she just ran inside the enemy base grabbed some files and ran straight out. When she got back all she wanted to do is sleep, but she needed to take care of Steve first. She got inside their bedroom and noticed Steve lying on the bed, pale and tired, with a warm towel on his head. She came up to home and laid on top of him, putting her legs on the sides of his body, and kissed his lips.

"hi" she said after kissing him "hey" "you feeling any better?" she asked worried "no, not really I vomited at least like 3 times before you got here. But I found the reason though" Steve said with a weak voice "well what is it?" "you remember that bar we went a few nights ago?" Natasha nodded "so the food there, it was pretty bad, I didn't really noticed I was a little waisted cause I brought that Asgardian drink that the gave me, so it's probably food poisoning." Steve explained. "is there anything I can do.to make you feel better?" nataha asked with a smirk, trying to sign him what she offered "well umm, there's this one thing but nahh I'm not sure you'll want it" Steve said with a smirk "oh come on, I'll do anything to make you feel better" Natasha said punching his shoulder
"well you can start by kissing me, and let's go with it" he said with a little giggle "I can go with it" Natasha said and smirked against his lips.

She started kissing him, and as Steve said, they just went with it, and Natasha made him completely forget that he was sick