One idea could be to explore the backstory of a minor character. For example, what was the life of a random student in Class 1 - B like before coming to U.A. High? Another could be a 'what if' scenario, like what if Izuku Midoriya didn't get One For All. Maybe he'd develop his own unique quirk through sheer determination and hard work. Or a fanfic could focus on the villains' side, showing how they came to be and their motives in more depth.
A cool plot for a My Hero Academia fanfic could be a time - travel story. A character goes back in time and tries to prevent a major disaster from happening in the hero world. It could also be about a new hero agency that is formed by some of the students who want to do things differently than the established agencies. They could face unique challenges and discrimination from the older heroes. And then there could be a story where a quirkless person creates a support item so powerful that it makes them a sort of 'hero' in their own way.
You could write a fanfic where the heroes and villains have to team up against a common, greater threat. Maybe an alien invasion or a powerful ancient quirk user awakens and wants to reshape the world. Also, a story about a character who has a quirk that is considered useless at first but they find a creative and unexpected way to use it to become a great hero. For instance, a quirk that makes you able to talk to plants could be used to gather intelligence from nature about villain hideouts.
A great plot could be that there is a mystery surrounding the origin of the dragon quirk. Is it related to some ancient power or a genetic experiment? The character sets out on a journey to discover the truth about their quirk. Along the way, they meet other characters with unique quirks and form alliances. They might also encounter villains who want to use their quirk for evil purposes, adding a layer of danger and excitement to the story.
One idea could be that Naruto characters are transported to the My Hero Academia world. Naruto himself could be seen as having a very unique quirk, like his chakra manipulation could be considered a superpower. They could team up with the students of UA to fight against a common enemy, like a group of villains who are after the secrets of chakra. Another plot could involve the My Hero Academia characters traveling to the Naruto world and learning about ninjutsu and how it differs from their quirks.
A great plot could involve Tsu going on a training journey outside of UA. She discovers a new aspect of her quirk during this journey. Like she finds out she can communicate with a certain type of animal that she previously couldn't. This new discovery then becomes crucial in a battle against a group of villains who are causing trouble in the area she's training in. She uses her newfound ability to gather intel and then defeat the villains.
One idea could be that Ladybug's Miraculous powers are somehow connected to a Quirk in the My Hero Academia world. For example, maybe her Lucky Charm ability could be seen as a very unique and unpredictable Quirk. Another plot could involve Ladybug and a My Hero Academia character teaming up to fight a common enemy that is causing chaos in both their worlds. This would require them to learn about each other's powers and work together in a way that combines the best of both universes.
One idea could be Deadpool getting transported to the My Hero Academia universe and causing chaos with his fourth - wall - breaking antics while also teaming up with Deku to take on a powerful villain. Another could be Deadpool trying to join UA High and his interactions with the teachers and students during the entrance exam.
One idea could be that the Pokemon have quirks like in My Hero Academia. For example, a Pikachu with an electricity - based quirk that allows it to not only use electric attacks but also manipulate the electricity in unique ways, like creating shields. Another idea is to have the characters from My Hero Academia become Pokemon trainers. Deku could start his journey with a weak - looking Pokemon that he trains to become very powerful, just like he does with his quirk. And a third idea could be to set the Pokemon world in the My Hero Academia universe, where there are both heroes and villains trying to control powerful Pokemon for different purposes.
One idea could be a crossover with the Harry Potter universe. Imagine Deku going to Hogwarts and learning magic while also using his Quirk. He could make friends with Harry and they could learn from each other's skills. Another idea is a crossover with the Avengers. The heroes from My Hero Academia could team up with the Avengers to fight a common, super - powerful enemy. Maybe All Might and Captain America could have an interesting conversation about leadership and heroism.
An interesting concept would be an OC who has a quirk that is based on art. For example, they can bring paintings to life. This OC could be a part of an art school within the My Hero Academia universe and use their quirk to fight villains who are attacking art galleries or museums. They would also have to train their quirk to be more combat - effective.
One plot idea could be a villain who is secretly a double agent, working for the heroes all along. They infiltrate the villain group and gather information. Another idea is a hero who loses their quirk and has to rely on their wits and combat skills alone, like Batman in the DC universe. And a villain - hero team - up to face a greater threat that neither can handle alone.
An interesting plot could involve an anti - hero who has a hidden agenda that is not entirely evil but also not in line with the traditional hero goals. Maybe they are trying to expose a corrupt part of the hero society from within. They could form alliances with some villains who also have a vendetta against the corrupt elements. This would create a complex web of relationships and moral dilemmas.