Who could be the main antagonist in a 'child harry potter lives in a frost' fanfiction?

One possible plot for this fanfiction could be that Harry Potter, as a child, is lured into a world of frost by a mysterious force. This world could be a parallel dimension. He has to figure out how to get back to his own world while also dealing with the challenges of the frost world. He might have to learn new spells or magic that are specific to the cold environment. He could also uncover some long - hidden secrets about his family or Hogwarts that are somehow related to this frost world.

Perhaps a group of poachers in the wizarding world who hunt magical animals could be the antagonists. If Harry is living as a rare magical animal, they would be after him. They might not know his true identity but would be attracted to the magical properties he has in his animal form. Harry would then have to use his wits and any remaining magical abilities to avoid being caught by them.

It could be a distant relative of Voldemort who has been biding their time in the shadows. They might have a vendetta against the Potter family for what happened to Voldemort. This relative could be secretly gathering followers and planning to strike at the second child when they least expect it.

It could be a dark wizard who wants to take over the toy house for its magical properties. Maybe he believes that there are powerful artifacts hidden within the toys that can make him invincible.

It could be a new dark wizard who is jealous of Harry Potter's fame and success. This dark wizard targets Harry's child, thinking that by causing trouble for the child, they can somehow diminish Harry's reputation in the wizarding world. He might try to frame the child for various dark magic incidents around Hogwarts.

Perhaps a long - lost relative of the Potter family who feels they were unjustly excluded from inheriting the manor. This relative could be jealous of Harry's status and the wealth associated with the manor. They might use dark magic to try and claim what they think is rightfully theirs, leading to a battle of magic and loyalty within the Potter family and among Harry's friends.

It could be a descendant of one of the Death Eaters who holds a grudge against the Potter family. They might try to finish what Voldemort started and target Albus specifically.

Maybe there could be a new antagonist, a dark shapeshifter who is jealous of Harry's power. This antagonist could be an old wizard who has been in hiding for centuries, waiting for the right time to emerge and take over the wizarding world. He sees Harry as a threat to his plans and tries to eliminate him.

Another possibility is a corrupted member of the Ministry of Magic. They might be trying to use Harry as a scapegoat to gain more power within the Ministry. They could be working with the Death Eaters or acting on their own, but they would be a significant obstacle for Harry as he tries to stay alive and free while on the run.

Perhaps a new dark wizard or witch who has infiltrated the Ministry of Magic and made sure Harry was sent to Azkaban. This antagonist could be working towards a bigger plan to take over the wizarding world and sees Harry as a major threat even when he's locked up.