Steve and Natasha being besties.
Steve calling Natasha when the frozen-for-almost-a-hudred-years thing is getting him down and Natasha coming over to his apartment and watching movies with him all night (“What do you mean you never saw Frozen?”)
Steve and Natasha going to a concert together and forgetting that they’re sort of famous and putting on ridiculous accents and pretending not to know who “thees Keptin Uh-muuricah and Bleek Weedow” are
natasha crashing on Steve’s couch when things get overwhelming and him finding her there in the morning and not asking how she got in, just making her coffee and waiting around for her to wake up instead of going on a run.
Natasha and Steve working out together
Steve and Natasha laughing really really really hard when they’re on tv together and the reporter asks if they’re together (the next day about 5,000 articles come out about them being in a relationship and steve pins one to his refrigerator and every time natasha comes over and sees it she dies laughing)
Natasha and steve teaching each other different fighting styles
Natasha and Steve