I'm looking for a specific fic, but I only remember one part/scene/whatever from it. Steve gets hurt somehow (I think he took a hit to the arm and/or torso?) while fighting alongside the Avengers. SHIELD has the means to treat him and anesthesia that works on him, but they refuse to use it unless the Avengers (or maybe just Clint and Natasha) agree to a two-year contract that eventually gets negotiated down to one year. I don't think Steve wanted them to agree to the contract at first.
It was on AO3 and probably gen, though it might have been Stony. Thanks! :-)