Who could be the main antagonists in 'Izuku's Time at Musutafu University' fanfiction?

Well, it could be about Izuku making new friends at the university. Maybe he joins some sort of hero - related study group and they all work together on projects.

Perhaps a new villain could emerge who specifically targets Izuku because of her new gender identity. This villain might see her as a symbol of change in the hero society that they don't want to happen. So they constantly attack her and try to break her spirit, thinking that if they can stop her, they can halt the progress of female heroes in general.

Some of the teachers at U.A. might also be antagonists. They could be secretly working for an organization that wants to control Izuku's powers for their own evil purposes. They would pretend to be helpful while actually setting traps and spreading misinformation about him.

It could be the traditional God of War villains like the gods who oppose Izuku. Maybe Ares, if he's still around in the fanfiction's version of the God of War world, would see Izuku as a threat and try to stop him.

It could be other villains who are jealous of Izuku's powerful dragon quirk. They might see his quirk as a threat to their own plans for domination or chaos.

The League of Villains would be obvious antagonists. They'd see Izuku with the All for One quirk as a threat or a potential recruit. Shigaraki, in particular, might be envious and want to take the quirk for himself.

Often, in 'izuku super soldier fanfiction', there are villains from the original series that become more menacing when facing Izuku as a super soldier. For example, All For One might be an even greater threat as he tries to either control or destroy Izuku.

There might be an ancient evil entity that has been trapped within the university grounds for centuries. When Harry arrives, it senses his power and tries to use him to break free. This entity could manipulate other students and staff to achieve its goal, making it a very dangerous and complex antagonist.

If Izuku is an alien, the antagonists could be other aliens who want to use his unique powers for their own evil purposes. Maybe they see Izuku as a key to conquering Earth or other planets.

In Kidnaped Izuku Fanfiction, likely antagonists could be rival villains who see Izuku as a threat to their plans. For example, those who want to stop him from becoming a great hero. It could also be villains who are after his unique quirk. Maybe they want to study it or use it for their own evil purposes. Another possibility is that it could be a group with a vendetta against the hero school he attends, and they target Izuku to send a message.