I remember that Bruce was the first to say loves you absent-mindedly at the end of a phone call to Steve and it kind of spread through the group. It was all platonic between them, just brotherly love. But it became habit for them to say love you to each other. There is a possibility that Natasha didn't say it, but showed it and they all knew anyway. It might have been from her point of view but I'm not sure.
If anyone knows it I would be really grateful - Also if anyone has any recs for good Team as Family fics that would be brill to - prefer Gen or if pairings Natasha/Clint and Tony/Pepper.