Who might be the antagonists in a 'Harry Potter makes an island' fanfiction?

There could be some of the house - elves that Harry has freed. They might choose to live on the island, using their magic to help with various tasks such as farming magical plants or taking care of the island's infrastructure. Also, some of the students from Hogwarts who were inspired by Harry could be there. They might be learning new forms of magic that are specific to the island or studying the unique magical ecosystem there.

Ron might be there too. He could use his skills in handling magical creatures to populate the island with friendly ones. And he could also help with fishing in the surrounding waters using magic, providing food for those on the island.

Perhaps Hagrid could assist. He has a deep understanding of magical creatures and could help Harry populate the island with them. He might also use his strength to help with the physical construction, like moving large rocks or trees.

Dumbledore, if he were still alive in the fanfiction, could offer his wisdom. He might guide Harry on the moral and magical implications of creating an island. He could also provide some powerful spells or artifacts that would aid in the construction process.

It could be the Ministry of Magic. They have often been shown to be corrupt and self - serving in the original series. If they try to manipulate Harry again, he might see them as the main antagonists and target them in his revenge.

Obviously, Voldemort could be one of the main antagonists. He might be the one who lures Harry into the League of Doom in the first place, with false promises. Another could be Bellatrix Lestrange. She is extremely loyal to Voldemort and would be very suspicious of Harry's presence in the league and try to expose or kill him.

Perhaps there are dark wizards who don't want Harry to gain more power through this lordship. They might fear that he'll use it to oppose them more effectively. So they would plot to stop him from fully taking on his new role.

Perhaps he uses the island as a secret training ground. He could practice advanced spells away from the prying eyes of Hogwarts faculty and students. Harry might also build his own magical fortress on the island for protection and privacy.

Hermione would probably be involved. She could help Harry research about the island, like its history and any magical properties it might have.

Hermione could be one. She might follow Harry to the island to help him out. Another could be Ron, his loyal friend. Or it could be some new characters created specifically for this fanfiction, like a wise old wizard who has been living on the island for centuries.