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.
A more complex plot could be that Ochako has an accident that causes her quirk to go out of control. The hero society blames her and ostracizes her. In her despair, she turns to villainy. She might form an alliance with other outcast villains and try to take revenge on the heroes who wronged her by using her now - enhanced and unpredictable quirk.
One popular plot idea could be a training session gone wrong. Katsuki's brashness and Ochako's determination clash during a joint training exercise, but this conflict eventually leads to a deeper understanding of each other. Another idea is a mission where they are forced to rely on each other. In a dangerous situation, Katsuki's power and Ochako's unique quirk work together in unexpected ways, sparking new feelings between them. A third idea could be a school event where they get paired up for a project. They start off at odds but as they work on the project, they discover they have more in common than they thought.
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.
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.
If Ochako becomes a villain, her relationship with Deku would be severely strained. Deku, being a hero - in - training, would be conflicted between his feelings for her and his duty to stop villains. He might try to reason with her at first, but if she continues on her villainous path, they could end up enemies.
A really cool storyline could be a time - travel one. Izuku and Ochako go back in time and meet their younger selves. They have to guide their younger selves to become better heroes without changing the future too much. Along the way, they see how their past actions and decisions led them to where they are now. And this experience also makes them realize how important they are to each other in their present lives.
One good Ochako jealous fanfiction is 'Green-Eyed Uravity'. In this story, Ochako gets jealous when Deku spends a lot of time with a new female hero in training. It really delves into her feelings of insecurity and how she tries to deal with them. The author does a great job of portraying Ochako's character.
Well, in such a fanfiction, it could be due to various reasons. Maybe Ochako realizes that their hero paths are leading them in different directions. It might also be a plot device to create more drama and character development for both Deku and Ochako.
One idea could be that Mustard discovers a new way to use his quirk that gives him an edge in the villain world. For instance, he finds a way to combine his gas - based quirk with some form of mind - control element. This could lead to a story where the heroes have to figure out how to counter this new threat.