One possible reason could be disillusionment. In some crossovers, she might see the Jedi Order's flaws more clearly when exposed to different cultures or ideologies from the crossover elements. For example, if it's a crossover with a more individualistic society, she may start to question the Jedi's collectivist approach.
She could have Clone Troopers as her allies. Some of them might have defected with her and believe in her innocence. They could provide military support and loyalty.
One plot idea could be Ahsoka finding herself in a parallel universe where she's considered a rogue Jedi. She has to team up with alternate versions of her friends to fight a common enemy. Maybe an ancient Sith cult has risen and they are the only ones who can stop it.
Another idea is a crossover where Rogue Ahsoka Tano stumbles upon a world full of magic. She has to use her Jedi skills in combination with the new magical elements she discovers there. For example, she might learn to combine the Force with magic spells to defeat an evil sorcerer.
One idea could be a crossover with Star Wars Rebels. Ahsoka could be betrayed by someone she thought was an ally in the fight against the Empire. Maybe a new character who was secretly working for Thrawn all along. This would lead to a complex plot where Ahsoka has to not only survive but also figure out who she can trust again.
The other Jedi would be affected in different ways. Some might see her as a traitor and become more strict in their views, while others might secretly sympathize with her. It could create a divide within the Order in the fanfiction.
First, you need to decide on the crossover universe. If it's with another Star Wars era, research that era thoroughly. For example, if it's the Old Republic, understand the politics, the different species, and the Force - using orders. Then, plan the betrayal carefully. It should be something that makes sense for the character of Ahsoka. For instance, it could be a betrayal of trust based on a misunderstanding or a character's hidden agenda. Next, develop Ahsoka's reaction. Will she be angry, sad, or more determined? Write her internal monologues to show her emotions. Also, think about how the two universes will interact after the betrayal. Will there be new alliances formed? Finally, don't forget to add some action and adventure to keep the readers engaged.
You could start by thinking about what would make Ahsoka Tano go rogue in the context of this crossover. Maybe she discovers a dark secret within the Jedi Order in this new setting. This could be the catalyst for her actions. Then, build a plot around her journey to expose this secret or fight against those who are trying to keep it hidden. Along the way, she could encounter various characters who either help or hinder her progress.
A frequent theme is identity. In a crossover like 'Ahsoka in the DC Universe', she has to redefine herself among all these new and powerful characters. Adaptation is another common theme. For example, in 'Ahsoka and the Avatar Crossover', she has to adapt to the concept of bending and the different power structures in that world. Also, the theme of discovery is often present. In 'Ahsoka's Multiverse Adventure', she discovers new powers, new species, and new ways of thinking as she jumps from one universe to another.
In Ahsoka Tano crossover fanfiction, including Obi - Wan Kenobi would be amazing. He and Ahsoka could have some really deep conversations about Anakin. Qui - Gon Jinn could also be a good character. Ahsoka could learn from him about the Living Force in more detail. And from the new Star Wars trilogy, Finn would be a great addition. He and Ahsoka could train together in combat, with Ahsoka teaching Finn more about the Force - sensitive combat skills.