Another idea is to write a fanfic about a team - up between unlikely heroes. Maybe a villain - turned - hero and a traditional hero working together to face a new threat that neither could handle alone. This can explore themes of redemption and cooperation.
A time - travel fanfic within the 'boku no hero' universe can also be interesting. A character could go back in time and try to change events, which would then have a ripple effect on the entire hero society, creating new relationships and challenges.
One popular idea could be creating an alternate origin story for a character. For example, giving Deku a different quirk acquisition experience that still leads to his growth as a hero.
One popular idea is an alternate universe where the characters have different quirks. For example, Bakugo could have a healing quirk instead of his explosive one, which would completely change his character arc and relationships. Another idea is a time - travel fanfic, where a character goes back in time to prevent a major disaster in the My Hero Academia world. It could be Deku traveling back to stop All for One from ever rising to power. And then there are the 'what - if' scenarios, like what if Izuku never got One for All? How would his life and the story unfold without this power?
A fanfic could be set during a school festival. Momo is in charge of one of the booths and Todoroki volunteers to help her. They have to deal with various problems like running out of supplies. Momo creates new items with her quirk while Todoroki helps with keeping things cool (literally with his ice) or heating up things when needed. In the process, they share some personal stories and get closer, realizing they have more in common than they thought.
One idea could be a story where Fem Todoroki has to overcome her self - doubts while training in a new and challenging environment. Maybe she's sent on a special mission with a group of heroes she doesn't know well, and she has to prove herself.
You could also write a fanfic about a time - travel plot. A character goes back in time to prevent a major disaster that happened in the 'boku no hero' world. They have to figure out how to change the past without completely disrupting the future, and along the way, they interact with younger versions of the beloved characters.
A cool plot could be that a villain in the Boku no hero world steals Iron Man's technology and starts creating chaos. The heroes then have to figure out how to stop the villain while also dealing with the unfamiliar technology. Or perhaps a young inventor in the Boku no hero world idolizes Iron Man and tries to recreate his suits, but with a twist related to quirks. This could lead to a story about the young inventor's journey, from being an unknown to becoming a key figure in fighting crime with their unique Iron Man - inspired creations.
One idea could be exploring Stain's backstory in more detail. Maybe his early life experiences that led him to his extreme views. Another could be a 'what if' scenario where Stain teams up with a hero, albeit reluctantly, to take on a greater evil. And a third idea could be to write from the perspective of someone inspired by Stain's ideology but trying to find a more peaceful way to bring about change in the hero society.
Izuku Midoriya is often a very popular character in 'boku o hero fanfic'. His journey from being a quirkless boy to a powerful hero gives a lot of room for creative interpretations. Katsuki Bakugo is also popular. His complex personality and his relationship with Midoriya provide great material for fanfic writers.
One idea could be a gamer who gets transported into the Boku no Hero Academia world and has to use their gaming skills to survive and become a hero. For example, they might have an in - game inventory system that they can use to access items that help them in battles.
A fanfic could explore what would happen if a Danganronpa character was born with a quirk in the world of Boku no Hero Academia. How would their analytical skills from Danganronpa mix with having a superpower?
One idea could be a fusion between Deku and All Might. Imagine Deku having not just One For All, but also All Might's combat experience and charisma from the start. It would change the dynamic of his battles and his relationships with other characters. Another idea is fusing Todoroki with a water - based hero, which could enhance his ice and water abilities even more and lead to new and creative ways of using his quirk in combat and rescue situations.