Who could be the main antagonist in 'Leia falls to the dark side fanfiction'?

One possible plotline could be that after facing great losses and betrayals, Leia starts to question the light side's values. Maybe the death of a close friend or the destruction of something she holds dear makes her vulnerable to the temptations of the dark side. She might then begin to explore the power that the dark side offers as a means to gain control and revenge.

It could be a long - lost moon - dwelling ninja clan that has a grudge against the Leaf Village. They see Naruto as a threat to their plans on the moon's dark side.

Palpatine could still be the main antagonist even if Luke turns to the dark side. He might try to use Luke as a more powerful weapon against any remaining Jedi or the Rebel Alliance. Palpatine would see Luke's newfound dark side power as a means to further his own control over the galaxy.

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.

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 the remaining Jedi. Since Rey is turning, the Jedi who still uphold the light side would see her as a threat. They would try to stop her from causing more harm with her newfound dark side powers.

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.

A Sith lord who has been secretly observing Ashoka could be the main antagonist. This Sith lord might see Ashoka's potential and want to turn her to the dark side to use her power for their own evil plans.

One possibility is that she becomes disillusioned with the Rebellion. Maybe she discovers some dark secrets within the Alliance that make her question their motives. For example, if she finds out that the Rebellion has been using unethical tactics in the fight against the Empire. This could push her towards the dark side as she feels betrayed by those she once trusted.