Who could be the main antagonist in an 'April and the Extraordinary World Fanfic'?

I'm not entirely sure, but I assume April is one of the main characters since the title has her name in it.

Madara Uchiha is another obvious candidate. Even though he was defeated in the original story, in a fanfic he could be resurrected with even greater power. His Sharingan abilities and his knowledge of the ninja world's secrets would make him a formidable antagonist for taking over the Naruto world. He could manipulate different clans and villages against each other before making his move to take over.

One idea could be that April discovers a new hidden power within her extraordinary world. Maybe she can communicate with the long - forgotten creatures that live in the deepest parts of the world she inhabits.

Perhaps a group of anti - technology extremists could be the main antagonists in an Ultron fanfic. They see Ultron as the symbol of all that is wrong with technology and are determined to take him down, no matter the cost. They might use their own advanced, but more rudimentary, technology to fight against Ultron. This would create an interesting contrast between Ultron's high - tech abilities and their more basic, yet effective, methods.

It could be someone who opposes Naruto's newfound admiration for Ganondorf. Maybe a traditionalist ninja who thinks Naruto is straying from the true ninja path by getting influenced by Ganondorf.

Maybe a mechanical tyrant in a steampunk - inspired setting. This tyrant has created an army of mechanical beasts and is trying to rule the city. Pyro, as a girl with fire powers, is the only one who can melt the metal parts of the beasts and stop the tyrant. The tyrant sees her as a threat to his rule and is constantly trying to eliminate her.

It could be an archaeologist who has been corrupted by the power of an ancient artifact related to the mummy. This archaeologist wants to use the mummy's power for his own gain, like becoming immortal or ruling the world. He would be constantly trying to stop Harry from helping the mummy.

Maybe an ancient evil spirit that feeds on the misery of the cursed. It sees Bearskin as a long - term source of its nourishment. So it uses all kinds of dark magic and tricks to keep Bearskin in his cursed state. It might also possess other characters to do its bidding and stop any attempts to break the curse.

A dark and mysterious sorcerer could also be the main antagonist. The sorcerer has a long - standing grudge against Byakuya's family or the place he protects. Using dark magic, the sorcerer sets up a series of deadly traps and curses, which ultimately lead to Byakuya's death.

In a crossover with Snow White, the Evil Queen could be the main antagonist. She might be jealous of Tinkerbell's magic and try to capture her to use her pixie dust for her own dark purposes.