It could be the Separatists. They might see Anakin as a valuable hostage to use against the Jedi and the Republic. His skills as a Jedi Knight make him a prime target for them to gain some sort of leverage in the war.
One possible plot development could be that his friends immediately launch a rescue mission. They might use their unique skills and resources to track down the kidnappers. For example, if Obi - Wan is involved, he could use his Jedi mind tricks to interrogate possible informants in the underworld.
One popular 'Anakin kidnapped' fanfic might be 'The Rescue of Anakin'. It could involve his friends or allies trying to save him from the captors. Another could be 'Anakin's Abduction and the Jedi's Quest', where the Jedi Order undertakes a dangerous mission to bring him back.
He could interact with Luke Skywalker. Imagine Anakin finally getting to meet his son as an ally in the Rebellion. They could train together and share their knowledge of the Force.
Anakin could be angry. He might see his other self as a threat, especially if one represents his dark side and the other his light side. There could be a power struggle between the two versions of himself as they try to assert dominance over the other. Or he could be curious and eager to learn from his other self, about what he could have been or what he can still become.
Anakin could encounter future versions of his friends or enemies from the past. For instance, he could run into a future version of Obi - Wan Kenobi who has also somehow traveled to that future time. Or perhaps he meets a new generation of Sith who have different motives and methods compared to the Sith he knew in his own time. They could challenge his understanding of the dark side and the Force in general.
In fanfiction, Ahsoka and Anakin can represent different things. Anakin, with his powerful Force abilities and his tragic fall, can be a symbol of the consequences of unchecked emotions. Ahsoka, on the other hand, can be seen as a symbol of hope and redemption. Writers might use their interactions to show how these two opposing concepts can coexist and influence each other.
In fanfiction, Ventress and Anakin often represent an interesting dynamic. Ventress is a complex character, and when paired with Anakin, it can create a lot of tension. Their interactions might be filled with conflict, as they are on different sides in the Star Wars universe. However, fanfiction writers can explore their possible understanding of each other on a more personal level, beyond their allegiances.
One great aspect of Anakin in Clone Wars fanfiction is his complex character development. Fanfic writers often explore his internal struggle between the light and dark sides more deeply. For example, they might create scenarios where Anakin has to make difficult choices earlier in the Clone Wars timeline than in the official story, which adds more tension and drama to his character arc.
Often, their interactions start from a place of conflict. Anakin's past actions as Vader create a barrier. However, as the story progresses, they may start to understand each other more. For example, Anakin could reveal his true self to Leia, the self that was once a good Jedi. This could lead to moments of deep connection and mutual respect between them. They might also have to work together against a common enemy, which would force them to communicate and cooperate, leading to a more developed relationship.