Who could be the main antagonist in'rey joins the dark side fanfiction' if Rey is turning to the dark side?

In this fanfiction, it could be that Rey has some personal losses that make her turn. She might lose someone dear to her and in her grief and anger, she decides that the dark side can give her the strength to prevent such losses in the future. She then starts learning the ways of the dark side, which changes her relationships with her friends.

Kylo Ren could still be the main antagonist even if Rey turns to the dark side. He might see her as a threat to his own power within the dark side hierarchy. Maybe he wants to keep her in check or even destroy her to maintain his dominance.

A plot twist could be that Rey has a dark heritage she was unaware of. When she discovers this, she feels a pull towards the Dark Side. She may struggle with this newfound knowledge at first, but eventually give in. In the story, her transition to the Dark Side could cause chaos in the Star Wars universe. The Resistance would be shocked and some might try to bring her back. However, the Dark Side could give her new powers and a different perspective on the Force. She could then start to reshape the Sith ideology, creating a new form of the Dark Side that is more in line with her own beliefs, leading to a whole new conflict in the galaxy.

Perhaps a powerful dark side cult leader. They could manipulate Ezra into believing that their way is the right one and that the dark side is a misunderstood power. The cult leader might use Ezra's own insecurities and desires to draw him into the dark side.

It could be Hawk Moth. He might finally succeed in corrupting Adrien. Hawk Moth could use Adrien's inner doubts and fears to his advantage. For instance, if Adrien is worried about losing his loved ones, Hawk Moth could promise him a way to keep them safe if he joins the dark side.

It could be the remaining Jedi. Since Luke is turning to the dark side, the Jedi who still uphold the light side values would be against him. They would see him as a threat to the balance they are trying to maintain and would try to stop him from fully embracing the dark side.

A Sith Lord who has been manipulating events from the shadows could be the antagonist. This Sith Lord might be trying to use Rey's connection to Anakin to bring about the return of the Sith in a new and more powerful way. He could be using dark side illusions to make Rey and Anakin distrust each other.

It could be Dumbledore. In a twisted take on the story, if Harry joins the dark side, Dumbledore would be the one trying to stop him. Dumbledore has always been the guiding force for the good side, and Harry's defection would be a huge blow. Dumbledore would then have to face the difficult decision of either trying to save Harry or stopping him by any means necessary, making him the antagonist from Harry's new 'dark' perspective.

Obviously, Rey is the central character as the story is about her fall to the dark side. Kylo Ren might also be a key figure. He could be either a catalyst for her fall, perhaps by tempting her with the power of the dark side, or he could be someone who tries to bring her back later on. Finn and Poe are also likely to be involved. They would probably be the ones trying to save Rey from the clutches of the dark side.

Obviously Rey herself is the central character. Kylo Ren often plays a role too. In some fanfictions, he might be the one who either tries to stop her from fully turning to the dark side because he has some sort of connection with her, or he might be the one who encourages her to embrace the dark side to be with him.