Who could be the main antagonist in a 'Harry Potter takes in a snake' fanfiction?

It could be a jealous Slytherin student. Since snakes are often associated with Slytherin, this student might feel that Harry has no right to take care of a snake. They could try to steal the snake or cause trouble for Harry, like spreading rumors that the snake is dangerous and should be removed from Hogwarts.

It could be a dark wizard who also has the ability to communicate with snakes and wants to use this power for evil. He might be jealous of Harry's connection with the snake and try to disrupt it or steal the snake for his own dark purposes.

It could be a dark wizard who also has an interest in the snake. Maybe he wants to use the snake's powers for evil purposes, like opening a portal to a dark dimension or controlling other magical creatures. So he becomes the main obstacle for Harry as he tries to protect the snake.

Maybe it's a dark wizard who has an interest in the snakes Harry is taking care of. He wants to use the snakes for some dark magic purposes. So he constantly tries to steal the snakes from Harry or even harm Harry to get to the snakes. For example, he could be a follower of Voldemort who believes the snakes hold some special power that can help bring back the dark lord.

It could be a dark wizard who wants to steal Harry's inheritance for his own gain.

The antagonist could be a jealous Slytherin student. They might see Harry's new snake as a threat to their own status in Slytherin house. So they try to steal the snake or harm it in some way.

It could be the person who sent the venomous snake after Harry Potter. Maybe a dark wizard who wants to harm Harry.

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.

Dumbledore himself could be seen as the main antagonist in this scenario. Since Harry is set on taking him down, Dumbledore's actions, whether they are truly malicious or just misinterpreted, would be the main obstacle for Harry to overcome.

Well, it could be that the snake is a magical snake that was being hunted by some dark wizards. Harry takes it in out of kindness. The snake then forms a bond with Harry and becomes like his secret helper. For example, it could slither into places Harry can't go and gather information for him.