One plot idea could be Ahsoka crossing over into the world of Harry Potter. She could be mistaken for a powerful witch at Hogwarts. She tries to use the Force in a world where magic has different rules. Maybe she teams up with Harry to fight Voldemort, using her combat skills and the Force to give them an edge.
How about Ahsoka in the world of The Lord of the Rings? She could be seen as a strange and powerful being by the Fellowship. Ahsoka helps them in their journey to destroy the One Ring. She uses her lightsabers and the Force to fight off orcs and other dark creatures, and perhaps has some interesting conversations with Gandalf about the nature of power and good vs. evil.
Ahsoka might crossover with the Transformers. She lands on Cybertron and has to work with the Autobots. The Decepticons are after a powerful Force - related artifact that Ahsoka has knowledge of. She and Optimus Prime lead the Autobots in a battle to keep the artifact out of the Decepticons' hands, while also trying to find a way for Ahsoka to get back to her own galaxy.
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.
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.
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 plot idea could be that there is a competition of sorts between the two worlds. Naruko represents her world and Vemon represents its world. They compete in a series of challenges that test their strength, intelligence, and adaptability. As they compete, they start to understand each other better and even develop a romantic relationship. This could also involve some cultural exchanges as they learn about each other's backgrounds and the different rules and values of their respective worlds.
A possible plot could be that Naruto is somehow transported to the world of Knights of Sidonia. He then has to adapt to the new environment and its rules. He might use his ninjutsu to help the people there fight the Gauna.
One idea could be that in the fanfiction, Ahsoka is kidnapped by a group of Sith cultists who want to use her connection to the Force for their dark rituals. They could take her to a hidden lair on a remote planet.
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.
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 plot idea could be that Ken Kaneki somehow gets transported to the world of 'Fairy Tail'. He might initially be seen as a threat due to his ghoul nature, but as the story progresses, he could form alliances with the Fairy Tail guild members. Maybe he helps them fight against a common enemy that has some similarities to the ghoul - like threats in his own world.