Here are some ideas. A group of students from the superhero academy could be stranded on a strange planet during a field trip. They have to use their powers in new and creative ways to survive and find a way back home. Or perhaps there's a prophecy about a'special one' among the students who will bring either great glory or destruction to the academy. This leads to a lot of tension and mystery as everyone tries to figure out who it could be.
A more relationship - centered plot could be about two characters who are from rival vampire clans at the academy. They fall in love, but they have to keep it a secret because of the enmity between their clans. They then struggle to find a way to be together without causing a war within the academy.
One idea could be exploring what would happen if a new member joined the Umbrella Academy. Maybe a time - traveling superhero from the future who has knowledge of a great threat coming. Another could be a story where the members lose their powers and have to rely on their wits and teamwork in a completely different way. For example, dealing with a powerful enemy who can nullify powers.
One idea could be a story where a new student arrives at Zodiac Academy with a mysterious power that disrupts the existing power balance among the houses. This could lead to unexpected alliances and rivalries.
One idea could be a new student arriving at Unicorn Academy with a special power that no one has seen before. This could lead to both envy and admiration among the other students.
A great plot for Gotham Academy fanfiction could be a story centered around a school competition that turns out to be rigged. The main characters suspect foul play and start their own investigation. Or perhaps a story where a character from a villain's family enrolls at the academy and has to deal with the prejudice from other students while also trying to prove they're not like their family. Also, a plot about a haunted dormitory at Gotham Academy would be really cool. The students would have to figure out the mystery behind the hauntings.
One idea could be a new student arriving at Mythos Academy with a mysterious power that no one has seen before. This power could attract the attention of both friends and foes, leading to various adventures as they try to figure out its origin and how to control it.
One idea could be a new student arriving at Asagao Academy and trying to fit in with the different cliques. Another could be a mystery within the academy, like a secret society that the main character stumbles upon. Maybe a love triangle between students from different majors.
Well, you could write a fanfic where Ladybug and Chat Noir get transported to an alternate universe. In this universe, their roles are reversed, and they have to figure out how to get back to their own world while dealing with the differences. Also, a plot could revolve around a Miraculous that has been lost for centuries suddenly resurfacing, and all the chaos and mystery that comes with it. Maybe a story about Ladybug having to deal with a personal crisis that affects her superhero duties, like losing her confidence after a major defeat.
Perhaps there's a dark secret hidden in the academy's history. A group of students accidentally stumbles upon it and has to work together to either keep it buried or expose it, depending on what they find out. Along the way, they face many obstacles and learn more about themselves and their magic.
A great plot could be that The Handler gets amnesia. Losing her memory, she has to rely on the kindness of the Umbrella Academy members she once opposed. This forces her to see them in a new light and also makes her question her own actions. It could lead to a journey of self - discovery for her within the world of the fanfiction.