How about a story where a group of villains and heroes are transported to an alternate dimension where the roles are reversed? The heroes now have to survive in a world that hunts them, and the villains find themselves in a position of power where they have to decide whether to be good or continue their evil ways. Another plot could be a villain who creates a quirk - enhancing drug that starts to spread among the heroes, causing chaos as some heroes become addicted and lose control of their enhanced powers.
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.
One idea could be that Deku gets tired of being constantly underestimated and bullied despite his efforts to be a hero. So, he decides to use his knowledge of hero strategies against them and becomes a villain. He could form his own group of outcasts who were also treated unfairly in the hero - centered society.
One idea could be that the 'Villain Class 1A' has to team up with the real Class 1A to fight a greater threat. Maybe a new super - villain emerges who is too powerful for either group alone. This would lead to some really interesting character dynamics as they have to put aside their differences.
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.
Another plot could involve Ochako being manipulated by a charismatic villain. This villain convinces her that the hero society is corrupt and that by joining the 'dark side' she can actually make a more positive change. She then uses her gravity quirk to disrupt hero operations, like making heroes' equipment float away during battles.
One plot idea could be that your OC is wrongly accused of being a villain because their methods of killing villains are too extreme for the hero society. They then have to prove their innocence while still continuing to hunt down the real villains. Another idea is that a powerful villain organization puts a bounty on your OC's head, and they have to fight off assassins while also taking on the main villains.
A more relaxing plot could be a beach vacation where the characters just unwind. They could build sandcastles, have picnics, and share stories. But of course, there could be some small challenges like dealing with a sudden rainstorm or a seagull stealing their food.
A great plot idea could be Shinsou going undercover in a villain organization. Since his quirk is so useful for deception, he could infiltrate and gather intel. Or perhaps a story where Shinsou has to train a group of new students with difficult - to - control quirks. He'd have to use his own experiences and his mind - control quirk in a mentoring way. Also, a plot where Shinsou discovers a new aspect of his quirk during a life - or - death battle, which gives him an edge and changes the course of the fight.
One idea could be a mystery in the dorms. For example, strange things start happening like items going missing or strange noises at night. The students could team up to solve it, using their different quirks in the process. Another plot could be a friendly competition between the dorm floors, like a quirk - based Olympics. This would show off their abilities and also strengthen the bonds between the students.
A fanfiction could focus on a special training exercise that goes horribly wrong. For example, a new type of quirk - suppressing technology is used during training, but it malfunctions and Class 1A has to rely on their non - quirk skills to survive and rescue each other. It would show their growth and teamwork in a different light.
Maybe a vampire villain who is trying to turn the heroes into vampires to create an army. The heroes have to figure out how to defeat this villain without getting bitten. They could use their quirks in creative ways, like using a fire - based quirk to repel the vampires.