Who could be the main antagonist in a 'harry becomes prefect fanfiction'?

It could be a power - hungry student who wants to undermine Hermione and Favo Prefect. This student might be jealous of their status as prefects and the respect they get from teachers and students alike. So, they try to create problems for them, like spreading false rumors or sabotaging their projects.

Maybe in the fanfiction, Harry becomes a prefect and it makes the Slytherins jealous. They start to plot against him, trying to get him removed from the prefect position. Harry then has to use his wits and newfound authority to deal with their schemes. He might also use this opportunity to improve relations between Gryffindor and other houses. He could start inter - house study groups which are initially met with resistance but eventually become a great success.

There could also be new antagonists. For example, some of the more traditional wizarding families who are against the idea of a female Harry. They might see her as a threat to the old - fashioned ways of the wizarding world and try to undermine her.

It could be Voldemort still. Even if Harry becomes associated with death, Voldemort is the ultimate symbol of death and destruction in the wizarding world. Their battle could take on a new dimension as Harry now has a different relationship with death.

There could be a jealous student. This student might be envious of Harry getting all the attention with his snake - related adventures. So, they would act as an antagonist by trying to undermine Harry's efforts in the snake fanfiction world. They could spread false rumors about snakes being dangerous or Harry's intentions being dark, causing trouble for Harry among his peers and teachers.

Maybe Voldemort or his followers could still be antagonists. Even though Harry is now a vampire, Voldemort might want to use his new state for his own evil purposes or simply view Harry as a nuisance that must be destroyed. Since Harry has changed, he might have new weaknesses that Voldemort could exploit.

Maybe a dark wizard who wants to capture the phoenix - Harry for his own evil purposes. This wizard could be after the unique powers that a human - turned - phoenix like Harry would possess. He might want to use Harry's phoenix form to gain immortality or to spread dark magic across the wizarding world.

The Ministry of Magic could be the main antagonist. They might view Harry's fascination with Dementors as a sign of him turning to the dark side. So they try to stop him from his research and exploration of Dementors, fearing he'll use their powers for evil. After all, Dementors are associated with dark magic in the eyes of the Ministry.

Another possibility is that some members of the wizarding government who oppose the idea of Harry being in Malfoy's care could be the antagonists. They might try to undermine the situation, create false accusations against the Malfoys, or even try to kidnap Harry to put him in what they consider a more 'appropriate' place.

In some cases, it could be other dark wizards or witches who are envious of Harry's new power. They might want to steal his Obscurial power for themselves or use it to gain dominance in the dark wizarding underworld. These antagonists might be minor characters in the original series but could be developed more in the fanfiction to create new and interesting conflicts for Harry.