Mother May
Most mothers are inundated with advice from the moment they announce their pregnancy. Whether they wanted it or asked for it. "Be careful or you'll spoil him." "Use time-outs." "Let him know who's boss."
Aunt May never had that. When her nephew came to "stay for a while," he was already a boy, not a baby. The only advice Peter's mother gave before rushing out the door was, "He likes his crusts cut off."
Peter is seventeen, and Aunt May still cuts off his crusts. If the other mothers knew, they'd tell her he's old enough to make his own sandwich. But May doesn't know any other way.
A/N: This fanfic is obviously inspired by the scene in 'The Amazing Spider-Man' movie where Peter's parents are leaving, but it is also inspired by a scene in 'Avengers: Earth's Mightiest Heroes' where Spider-Man pulls a sandwich from his bag and says, "PB&J with the crusts cut off – thanks, Aunt May!"