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.
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.
Another plot could be set in an alternate universe where Ahsoka manages to reach out to the little bit of Anakin still left in Darth Vader. She tries to redeem him, and through a series of encounters, they start to question their own paths and the Sith vs. Jedi ideology.
Yes, there are likely some fanfics with this concept. Fanfic writers often explore unique and alternative storylines. They might be interested in exploring what would happen if Ahsoka, who was Anakin Skywalker's apprentice, ended up in a situation where she worked for Darth Vader (Anakin's Sith persona). It could involve complex character dynamics and a re - imagining of the Star Wars universe.
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.
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.
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.
Well, a cool plot might be that Ahsoka gets trapped in a Sith - created illusion world by Vader. In this world, she has to face her past traumas and fears related to Anakin's fall. Meanwhile, Vader is conflicted as he watches her struggle, memories of his past with Ahsoka resurfacing. Or there could be a story where they both are on a mission to retrieve a powerful Jedi/Sith artifact, and their paths cross in a race against time.
One possible plot could be a story where Darth Vader, in his full potential, has a moment of self - realization during a battle against Ahsoka. He might start to question his dark path and Ahsoka, seeing this glimmer of Anakin in him, tries to pull him back to the light. It could be a complex emotional journey for both characters as they grapple with their past relationship as master and apprentice.
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.
Perhaps Darth Vader's dark side powers are misinterpreted in the Naruto world as a new and extremely dangerous form of jutsu. Naruto and his friends might try to find a way to seal these powers. Meanwhile, Vader is on a quest to find a way back to his own universe, and in the process, he starts to question his own dark ways after seeing the camaraderie among the Naruto characters. He could end up having a change of heart and use his powers for good in the Naruto universe.