The Avengers themselves might feel a great sense of guilt. If they were somehow involved in the events leading to her death, or if they failed to protect her, it could strain their relationships with Spider - Man. They might also become more protective of other civilian family members of their members.
In some Avengers fanfictions, Aunt May might die from an attack by a supervillain. For example, if the villains target Spider - Man's loved ones to get to him, Aunt May could be in the crossfire. Maybe a group like the Sinister Six raids Peter Parker's home, and in the chaos, Aunt May is fatally injured.
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.
Peter might initially be in a state of shock. He could isolate himself from his friends and the world around him, constantly replaying memories of Aunt May in his head. He may also feel a great sense of guilt, thinking that he could have done more to protect her.
The Pokémon world in the fanfiction could be thrown into chaos. Ash was known as a great trainer and his presence had a certain influence on the balance of power. With his death, other trainers might start scrambling for power or resources, thinking there's a void to be filled. Also, the regions he visited might experience a decline in tourism as many trainers and fans were attracted by Ash's adventures there.
He could become more withdrawn.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.
She might be shocked at first. After all, Spiderman is constantly in danger, and she has always seen Peter as a normal boy. So, it's a big revelation for her.
One consequence could be that the Avengers are left in disarray. Tony was a key figure in terms of resources and technology. His death might mean a lack of funding and advanced equipment for the team.
The writers of the fanfiction may lose motivation. Without financial support from Tony, they might not be as enthusiastic about writing new stories, which could lead to a decrease in the quantity and quality of Avengers fanfiction available.
One consequence could be that his friends are filled with grief and a strong desire for revenge. They might go on a rampage to find the ones responsible for Naruto's death.
One possible consequence is that he could send other agents or superheroes to stop them. He has a wide network of resources and connections, so he could easily assemble a team to deal with the Rogue Avengers.