One idea could be a what - if scenario where Anakin in his pre - Vader state somehow gets a glimpse of his future as Vader. He could then fight against the dark side within himself that would turn him into Vader. Another could be a time - travel plot where Vader is sent back to face Anakin, and Anakin has to decide whether to accept his possible future or fight against it.
Well, a great plot could be a battle in the Force realm. Anakin, representing his former self with hope and light, battles Darth Vader, who is the embodiment of his fallen state. Maybe there could be a mysterious Force - related object that they both are trying to obtain, and their battle over it represents Anakin's struggle between his good and evil selves. It could also involve the ghosts of Jedi Anakin knew, guiding him in the fight against Vader.
A fan fiction could also explore a parallel universe where Anakin and Darth Vader are two separate entities that co - exist. They are forced to fight not because of Anakin's fall, but due to some external force that wants to see the two most powerful Sith - like beings battle it out. This could lead to an exploration of their different fighting styles and the power dynamics between them.
It really depends on how you write it. If it's Anakin at his peak before turning to the dark side, he has a lot of raw power and potential. But Vader has years of experience as a Sith Lord. So, it could go either way.
One plot idea could be a time - travel scenario where Ahsoka is sent back in time and has to face Darth Vader before he fully became the Sith Lord she knew. She could try to prevent his fall. Another idea is a story set in an alternate universe where Ahsoka and Vader team up against a greater threat, forcing them to put aside their differences. Maybe a plot where Ahsoka is captured by Vader and he has an internal struggle about what to do with her, given their past relationship.
One interesting plotline could be Anakin's struggle with his past self as Vader. Maybe in the fanfic, Anakin tries to prevent Vader from making the same mistakes he did, leading to intense battles of will and lightsaber duels.
Luke Skywalker could be another key character. Since he is Vader's son, his presence could add an interesting dynamic. He might be the one who somehow triggers the battle between Anakin and Vader, or he could be in a position to influence the outcome of their fight, perhaps by appealing to the remaining good in Anakin or by facing off against Vader himself in a three - way struggle.
Well, you could have a fanfic where Darth Vader travels back in time to the Clone Wars era. He could try to change certain events to better suit his later goals as a Sith. For example, he might attempt to influence the development of the clone army in a way that would make them more loyal to him personally rather than the Jedi or the Republic. This could lead to all sorts of conflicts and power struggles within the already complex Clone Wars setting.
A plot could involve Ahsoka trying to redeem Darth Vader. She might attempt to reach out to the Anakin Skywalker she once knew, and through a series of encounters, Vader starts to question his path in the dark side. For example, they could be forced to team up against a common enemy, like a new Sith Lord who wants to destroy them both. This situation would put Vader in a position where he has to choose between the Sith teachings and his old friendship with Ahsoka.
One idea could be a fanfic where Darth Vader has a secret apprentice who is an original character. This OC could be a young Force - sensitive being from a hidden planet. The story could revolve around Vader training this apprentice in the ways of the Dark Side, while also facing internal conflict as he sees some of his own past self in this young OC.
One idea could be a story that focuses on Anakin's internal struggle between his love for Padme and his fall to the dark side as Darth Vader, while Luke and Leia unknowingly grow up in the shadow of their father's actions. It could explore how their lives might have been different if Anakin had not turned, and how they eventually come to terms with his true identity.
One idea could be exploring Darth Vader's identity before he became encased in the suit. Maybe he rediscovers his old self and tries to reconnect with his past relationships. Another could be him having to face the Jedi without the intimidating suit, relying solely on his raw Force abilities.