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.
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.
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.
One idea could be a crossover with the Star Wars Rebels crew. Ahsoka could team up with Ezra and Kanan to face a new threat that combines elements from different eras of the Star Wars universe, like a Sith Lord using ancient Jedi artifacts in a new way. Another plot could involve a crossover with the Mandalorian. Ahsoka could cross paths with Din Djarin and Grogu, perhaps helping them in a battle against remnants of the Empire while also sharing her wisdom about the Force.
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.
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.
One idea could be Ahsoka getting transported to the DC universe and teaming up with Batman. She could use her combat skills and Force - sensitivity to help him fight against Gotham's villains. Another plot could involve her meeting Wonder Woman and learning about the different types of power and heroism in the DC world. Maybe she gets caught in the middle of a battle between the Justice League and their enemies and has to use her Jedi wisdom to broker peace.
Perhaps a fanfiction where they both find themselves on a mysterious planet. They have to figure out the planet's secrets and survive its strange inhabitants. Along the way, they strengthen their bond and learn more about each other's growth since they last saw one another.
One plot idea could be that the OC is a fellow Jedi in training. They start off as rivals, constantly competing in lightsaber duels and Force training exercises. As they face challenges together, like a Sith threat to the Jedi Temple, they gradually develop feelings for each other. Another idea is that the OC is a mechanic who helps Ahsoka repair her ship during a difficult mission. They bond over their shared love for adventure and over time, romance blossoms. A third idea could be that the OC is from a different planet with a unique culture. Ahsoka is intrigued by this culture and the OC's different perspective on life, leading to a romantic connection as they learn more about each other.
A possible plot could involve Ahsoka being betrayed by someone she trusts deeply within the Jedi or among her friends. This betrayal could be so severe that it pushes her over the edge, and she turns to the dark side for revenge. She then uses her newfound dark side powers to seek retribution against those who wronged her.