Peter Parker is the resident child in Avengers Tower. He had helped Tony during Civil War even though he didn’t really know the circumstances. After that he had been really eager to get back into the Avengers, eventually Y/N convinced Tony to fully recruit him. Once he was recruited and the team found out his parents had died Bucky and Y/N adopted him. He’s essentially their son and live in the Tower itself along with a secluded brownstone in Brooklyn for just Bucky, Y/N and Peter. The Avengers became one big family, though missions do get stressful.