Who could be the main antagonist in 'Harry gets turned into a snake fanfiction'?

It could be Voldemort. He might see turning Harry into an elf as a way to weaken him. Since elves are generally seen as lower in the wizarding hierarchy, Harry in this form would be less of a threat to Voldemort in the eyes of many wizards.

It could be Draco Malfoy. Maybe he somehow manages to use a new spell or a dark object to turn Harry into a ferret out of spite. He might then try to keep Harry in that form to humiliate him in front of the whole school.

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.

The main antagonist could actually be Anakin's own self - doubt. Since he's in a child's body but has an adult's memories, he might struggle with feelings of inadequacy. This internal struggle could act as an antagonist, preventing him from fully embracing his new situation and using his abilities to the fullest. It could be a psychological battle within himself that holds him back more than any external foe.

Perhaps a powerful sorceress. She could be jealous of Robin's connection to Batman and the other heroes, so she uses her magic to turn Robin into a girl as a way to humiliate and weaken him. The sorceress could then try to use Robin's new form to her advantage, like trying to make Robin turn against the heroes or something.

It could also be a new villain. Maybe someone who has been waiting for Sonic to be in a vulnerable state. This new villain could have a special power or weapon that is more effective against Sonic as a kid. For example, a device that can slow down Sonic even more or nullify his powers temporarily. They might target Sonic not just because of his weakened state, but also because they know that his friends will be distracted trying to help him get back to normal.

The main antagonist could be a jealous classmate. This classmate is envious of Ron's friendship with Harry and Hermione. So, they find a way to use dark magic to turn Ron into a fiend, hoping to drive a wedge between them. However, as the story progresses, they realize the consequences of their actions are far more serious than they thought.

Another possibility is that the main antagonist is an evil scientist who was responsible for Ash's transformation in the first place. This scientist could be trying to create some sort of chaos in the Pokémon world by turning a well - known trainer like Ash into a girl. And now, Ash as a girl has to stop this scientist from causing more harm to the Pokémon world.

There might be a jealous friend or acquaintance who feels that Stiles, as a girl, is getting too much attention. This person could then start spreading rumors or causing trouble for Stiles in an attempt to bring her down.

It could be a dark wizard who has a long - standing vendetta against Ron's family. This wizard might see turning Ron undead as a way to get revenge on the Weasleys. He could be lurking in the shadows, trying to make Ron's undead state even worse by casting more dark spells on him.