As he spends more time as a Sith, he might start to feel a sense of emptiness. He realizes that the power he sought isn't fulfilling. He could then have a moment of self - reflection. Maybe he meets a character who challenges his beliefs, like a young Force - sensitive who still believes in the good in the galaxy. This makes him question his path and start to seek a way back from the dark side.
Well, a very common theme is the internal struggle. Anakin is constantly fighting within himself in these fanfics. There's also the theme of loyalty, whether it's his loyalty to the Sith or any remaining loyalty to his Jedi past. And the theme of revenge often comes up, as he might seek revenge on those he feels wronged him as a Sith.
The novel of Revenge of the Sith is canon. It aligns with the established Star Wars canon framework and adds depth and detail to the events depicted in the movie of the same name.
One great Anakin Sith fanfic is 'The Fall of Anakin Skywalker'. It delves deep into his transformation into Darth Vader. It shows how his inner turmoil and the influence of the dark side gradually overtook him. The author does a wonderful job of portraying his struggle between the light and the dark, making it a very engaging read.
Padmé is often paired with Anakin in fanfiction. Even though he has turned to the Sith, their love story still has a lot of potential for exploration. Writers might create scenarios where Padmé tries to bring Anakin back from the dark side. Another popular character is Obi - Wan. Their relationship as master and apprentice can be further developed in the context of Anakin's Sith journey. There could be intense confrontations or moments of reluctant understanding between them.