A new character could be a family member of All Might. Maybe he has a long - lost nephew who discovers his relation to All Might and decides to follow in his footsteps, but has to overcome his own insecurities and lack of experience. Or a family member of Todoroki Shoto who has a quirk that combines both fire and ice in a unique way, and they come to help Todoroki understand and master his own dual - natured quirk better.
A character with a quirk that allows them to manipulate time on a small scale, like being able to slow down time for a few seconds in a small area. This could add a new dynamic to battles. Another could be a hero - in - training from a very different cultural background, say someone from a tribe in the Amazon with a quirk related to nature and animals. There could also be a villain whose quirk is to create illusions so real that they can even affect a person's sense of touch.
Stain could be considered as an anti - hero in fanfiction. His extreme views on heroes, while not entirely acceptable, could be delved into deeper. He believes that only true heroes should be recognized and is willing to take extreme measures to prove his point. A fanfiction could explore a different side of him, perhaps one where his actions are more nuanced.
One idea could be exploring the family backgrounds of the minor characters. For example, how the families of the students in Class 1 - B deal with their children having quirks and aiming to be heroes. Another could be a story about a hero's family dealing with the fame and danger that comes with their relative being a hero. Maybe a hero's family is targeted by villains, and they have to figure out how to protect themselves.
A group of nomadic mice. They have different skills and traditions compared to the Redwall mice. Their arrival at the abbey could cause some cultural clashes at first, but eventually, they could learn from each other and contribute to the abbey's growth. This would add more diversity to the characters in the fanfiction.
A young stargazer from Earth could be a new character. This character could be someone who has always been fascinated by the stars and dreams of traveling to other planets. When the Little Prince lands on Earth again, they meet and the stargazer becomes his guide on Earth, showing him all the new things that have happened since his last visit. Another potential character could be a talking moonbeam. It could offer the Little Prince advice and wisdom, as well as some magical abilities to help him on his journey.
A new character could be a therapist who has a unique approach to helping the main character. This therapist could introduce new ideas and methods of healing that the main character hasn't encountered before.
A healer from a far - off land could be an interesting addition. This character could bring in new knowledge of magic and medicine that the existing characters are unaware of. Maybe they have a special connection to nature that allows them to heal in ways not seen before in the story.
A young Martian inventor could be a great addition. This character could create unique gadgets and machines that help the protagonists in their adventures. For example, a flying device that can travel at high speeds across Mars.
A mysterious traveler passing through the town could be a new character. This person has seen many strange things in their travels and is not afraid of Edward. In fact, they see his potential and encourage him to leave the town and see the world.
A healer character could be added. This healer could be the one who discovers a hidden power within the apprentice that could change the course of their journey. Another potential character could be a mysterious traveler. This traveler has seen many different worlds and has knowledge that could either help or hinder the apprentice.