One common theme is mentorship. Anakin often acts as a mentor to Ashoka, guiding her in the ways of the Force. Another theme is friendship. Their relationship is a deep friendship that withstands many challenges. For example, in some fanfics, they support each other during difficult battles or when facing political intrigue within the Jedi Order.
There's a fanfic called 'Ashoka and Anakin: The Unspoken Alliance'. It focuses on the unspoken understanding between them. In this fic, they face a powerful enemy together and their bond grows stronger as they figure out how to defeat it. It's full of action and great character moments.
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, obviously Anakin and Vader are the main characters. Anakin is his pre - Darth Vader self, full of potential and hope at one point, and Vader is the dark, powerful Sith Lord he becomes.
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.
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 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.
In some fanfics, Anakin's turn to Vader during the Clone Wars might be accelerated by a series of events that test his loyalty more severely. For example, he could be framed for a crime against the Jedi Order. This false accusation could make him feel betrayed by the very people he has sworn to serve. As a result, his connection to the dark side could strengthen as his anger and confusion grow.
In such a fanfiction, one possibility is that Anakin Skywalker might initially be in shock upon seeing Darth Vader. He could struggle to come to terms with what he has become. Maybe there would be a battle of wills as Anakin tries to fight against the dark side within Vader.