Steve was a king (or at least royalty) and Tony worked in the city he was residing over as a Smith. He's a foreigner, but towards the end of the story it turns out he is actually also royalty of another country (but Stane kidnapped him when he was very young (? I think ?)).
I think they originally meet because Steve is being pressured to find a husband, but not sure about that. I might be mixing this up with another medieval fic where Tony is the royal Smith who makes Steve's shield (if someone knows that fic please also let me know :D)
Thanks in advance !