Who could be the main antagonists in 'Harry Potter goes to Marauders era fanfiction'?

Perhaps some students who are jealous of Harry's fame could be antagonists. They might try to undermine him during training exercises.

Obviously, Harry himself is a very popular character in these fanfics. After all, he's the one who has traveled to the Marauders era. Then there are the Marauders - James, Sirius, Remus, and Peter. Fans love exploring their relationships and personalities in more depth. Lily Evans is also quite popular as she's Harry's mother. Her interactions with Harry and how she develops in this different scenario are often a big draw for readers.

The main characters are Harry Potter for sure. He's the one who is reborn into the Marauders era. Then there are his parents, James and Lily. They are important as Harry gets to know them in a whole new way. The Marauders are also central. Sirius, with his wild and loyal nature, Remus with his werewolf secret, and Peter, who later betrays them in the original story. Their relationships with Harry add a lot of depth to the story.

A great plot idea could be Harry getting involved in the Marauders' pranks but also using his experiences to guide them towards more responsible magic use. He could also be a key figure in uniting different groups in the wizarding world during that time. Since he has a different perspective, he might be able to bridge the gap between pure - bloods, half - bloods, and Muggle - borns much earlier, which could have a huge impact on the future and the fight against Voldemort.

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.

The main antagonists could be those who don't want Harry to receive a proper Hogwarts education. Maybe some dark wizards who fear that Harry will become too powerful if he goes through the Hogwarts training. So, they plot to keep him away from Hogwarts.

A great plotline in such fanfics is when Harry has to deal with the time - travel paradoxes. Since he's in the Marauders era, any change he makes could have a huge impact on his own future. He might be hesitant to do too much at first. Also, his relationships with the Marauders are fascinating. He could become like a mentor figure to them in some ways, teaching them things he learned from Dumbledore. And the whole idea of him being in a world where Voldemort is still rising but in a different stage is full of potential for exciting story development.

One possible antagonist could be the time itself. Since Harry is messing with the natural flow of time, there could be some sort of time - based magic or entity that tries to stop him. It might be a time - keeper or some ancient magic that protects the integrity of the timeline.

I really like 'The Marauders' by an unknown author. It focuses on their adventures and how they formed their tight - knit group. It has some really exciting plot twists, like how they dealt with certain dark magic threats in their school days. It's a fun read that keeps you on the edge of your seat.

One possible antagonist could be a corrupt wizard in a high - ranking position in the Ministry of Magic's financial department. This wizard might be trying to cover up his misdeeds and would see Harry as a threat to his scheme.