A great plot idea would be a mystery - centered one. In this 'My Hero Academia Fantasy AU Light Novel', there could be a series of strange magical events occurring in the world. The characters have to use their unique magical abilities (like Todoroki's ice and fire magic) to solve the mystery. Maybe there's a dark magic user trying to disrupt the balance of the magical world, and the heroes must stop them before it's too late.
One idea could be a story where the characters are transported to a parallel fantasy world where their quirks work differently. For example, Midoriya's One for All might give him the ability to communicate with magical creatures instead of just enhancing his strength. Another could be a pre - quirk era story in a fantasy setting, where they have to rely on magic and swordsmanship like traditional fantasy heroes. A third idea might be a time - travel plot where they go back to a crucial point in the history of heroics in a fantasy version of their world and have to make sure things happen correctly to preserve the future.
It could be All for One, but in a more magically - powered form. Instead of stealing Quirks, he steals magic spells and powers from other magic - users. His goal could be to become the most powerful magic - user in the world and rule over all the magical kingdoms.
One idea could be that a kaiju suddenly appears in the My Hero Academia world and the heroes have to figure out a new way to combat it since their usual powers might not be as effective. For example, they might have to work together in a more strategic way than ever before, combining different quirks to create a new type of attack.
Well, perhaps a plot where we see the making of the hero costumes. The designers, their inspiration, and the challenges they face like getting the right materials for the students' unique quirks. Also, we could explore how the news agencies work in this AU. How they get exclusive scoops on the heroes and villains. And what if there's a group of side - characters who are the real power behind the scenes, like they secretly control the flow of information and events in the hero world.
Perhaps a plot where Mineta enters a parallel dimension where the rules of his quirk are different. He has to adapt quickly to survive and find a way back home. This could lead to some interesting character development as he faces new challenges and has to rely on himself more. He might also make new friends or enemies in this parallel dimension.
The 'Plant Symbiosis' quirk would be a great addition to a fanfiction. The individual with this quirk can form a symbiotic relationship with plants. They can communicate with plants, make them grow rapidly, and even use plants as an extension of their body for things like creating shields or lashing out at enemies. This quirk could bring a whole new element of nature to the story.
One plot idea could be that the Saiyan OC is mistaken for a new type of villain at first. As they try to prove they're not a threat, they start to make friends and learn about heroism. Another idea is that they discover a connection between Saiyan powers and some of the hidden secrets in the MHA world. Maybe there's an ancient power source that only a Saiyan can unlock.
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.
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.