He could become more withdrawn. Losing Aunt May, who was like a mother to him, would be a huge blow. He might isolate himself from his friends and even from his crime - fighting duties for a while as he deals with his grief.
One possible fanfiction could be about Aunt May discovering Peter's identity as Spider - Man in a more comical way. Maybe she accidentally walks in on him changing into his suit and just stares for a moment before bursting out laughing and saying something like 'Well, I should have known with all those late nights and mysterious bruises!'
One great fanfiction idea could be Aunt May finding out Peter is Spider - Man in a really emotional way. Maybe she stumbles upon his suit while cleaning his room and has to confront him. This would add a whole new layer of drama to their relationship.
New enemies could emerge. Maybe some villains would see his vulnerability after Aunt May's death and try to take advantage. As for alliances, he might team up more with other superheroes like Iron Man. He'd need more support now that he's lost his main source of emotional support at home.
Well, in certain fanfiction scenarios, Aunt May could die as a result of a villain's attack. Maybe the bad guys target Peter through her, and in the chaos of the fight, she gets fatally injured. This would add a lot of angst to Peter's story as he'd have to deal with both the loss and his thirst for revenge.
One plotline could be that Aunt May gets superpowers herself. Maybe she was exposed to some of the same stuff that created Spider - Man's powers. This would completely change the dynamic as Peter now has to deal with a superpowered Aunt May who is eager to help him fight crime, but he's also worried about her safety.
Another way to portray her differently is to make her more of a fighter. Instead of always being in the background worried about Peter, she could learn some self - defense moves and actually help Spider - Man in a physical fight. This would be a really cool and unexpected twist in the fanfiction.
Well, it would change him a great deal. He'd probably go through a period of intense grief. This could lead to him isolating himself from his friends like Ned. However, he'd also realize that Aunt May would have wanted him to keep being Spider - Man. So he'd start to focus more on the big - picture threats to the city, rather than just small - time crime. His motivation would shift from just doing the right thing to honoring Aunt May's memory.
She might also be proud. Peter is using his powers to help people, and Aunt May, being a kind - hearted person, would likely be proud of him for that. She could start to brag about him to her friends in a very discreet way, of course. And she would probably be more worried about him than ever, constantly thinking about all the risks he takes every time he goes out as Spider - Man.
One great 'Ultimate Spider - Man Aunt May fanfiction' is 'Aunt May's Strength'. It shows Aunt May in a more empowered role, dealing with the knowledge of Peter's double life. It gives her character more depth and agency.