Maybe a story where the Executor encounters a strange and powerful alien race. Vader has to decide whether to fight or negotiate, and this encounter could change his view of the galaxy and his place in it. The story could explore themes of power, diplomacy, and the unknown.
One possible fanfiction could be about the construction of Vader's Executor. Imagine the Sith Lord overseeing every detail, from the massive engines to the weapon systems. The story could explore the dark side influence in its creation and how it became a symbol of Vader's power in the galaxy.
One idea could be the apprentice's struggle with the dark side. For example, they start to question Vader's teachings when they see the harm it causes to innocent planets. They might secretly try to find a way to use the Force for good within the constraints of being Vader's apprentice.
A plot could involve Darth Vader having visions of a different future where he and Princess Leia are on the same side. These visions start to haunt him, and he begins to subtly protect her from the Emperor's wrath. In the meantime, Leia senses a change in Vader's behavior and tries to figure out if she can use this to the advantage of the Rebel Alliance. For example, she might try to convince him to turn against the Empire completely.
One idea could be that you insert yourself as a new apprentice to Darth Vader. You start with basic training, learning the ways of the dark side from him. Maybe you discover a hidden power within the Force that Vader is also intrigued by, and together you explore its potential.
A cool concept would be a crossover with the Star Trek universe. Darth Vader's Sith ideology would clash with the Federation's principles. He might be intrigued by the advanced technology of the Star Trek world, and there could be an epic battle between the power of the Force and the technology of the future. Or perhaps he'd form an unlikely alliance with some of the more morally ambiguous characters in Star Trek.
One plot idea could be that R2D2 is captured by Darth Vader. But instead of destroying the little droid, Vader becomes curious about the information it might hold. He tries to hack into R2D2's memory, leading to a series of tense moments as R2D2 tries to protect the secrets within. Maybe R2D2 has some long - lost Jedi knowledge that Vader thinks could help him overthrow the Emperor.
A cool idea could be a fanfiction where Vader has a vision of an alternate future where he stayed with Padmé and turned away from the dark side. This vision haunts him during his missions in the Star Wars Rebels era, making him more introspective and less ruthless for a while. He might start to make different decisions based on this vision, much to the surprise of the Emperor and his subordinates.
One idea could be exploring the origin of a new, mysterious force - user in the Shadow Wars. Maybe it's a forgotten Jedi or Sith technique that resurfaces and causes chaos. Another could be focusing on the relationship between a group of rebels and how they deal with the added threat of the Shadow Wars.
A great plot for Star Wars The Clone Wars fanfiction could be centered around a new, unknown planet that gets caught in the middle of the war. The planet has its own unique species and culture. The story could follow how the clone troopers and the Jedi interact with this new civilization, whether they try to protect it or use it for their own strategic advantages. Or perhaps a story where a group of clone troopers start to develop their own individual personalities and question their loyalty to the Republic due to some unethical orders they receive. This could lead to a conflict within the clone ranks and force the Jedi to take sides.
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.