recessional has posted an adorable and very practical story wherein Bucky has an Emotional Support Animal, a kitten who's gradually turning into a cat, and Clint takes it up himself to arrange to get the kitten fixed in the way that will least traumatize Bucky. Because that's what friends do. Go read
Things Creep Up On You Technically it's part of her Blue Eyed Boys fic series, but it works as a standalone if you posit that before the story started, Steve and Bucky moved into an apartment in Brooklyn, Steve has made trying to get Bucky well his raison d'ĂȘtre in life, they adopted a stray kitten some months ago, and the other Avengers (and Sam) are helping as much as they can. Which are all easy things to posit.