One example could be a story where Luke discovers Obi - Wan had a daughter and they team up to face a new threat. Maybe she has some hidden powers that are crucial in the battle.
It could introduce new storylines. For instance, if she has a unique connection to the Force, it might change how the Jedi are perceived. Maybe she has a different approach to using the Force that challenges the traditional Jedi ways.
There may not be mainstream, widely - publicized fanfictions with Obi - Wan gagged. But some independent writers might have created stories around this concept. It could be that in a story, Obi - Wan is gagged during a diplomatic mission turned hostile. His captors want to silence him to gain an advantage in negotiations. This could lead to a complex plot where his friends have to use their wits and skills to free him and resolve the diplomatic crisis.
Count Dooku could be a prominent character. Given his own fall to the dark side, he might be a mentor or a rival to Obi - Wan in the fanfiction. Mace Windu is another one. His strict view of the Jedi Code and his relationship with Obi - Wan could be explored in the context of Obi - Wan's turn. And of course, there are the various Sith Lords and dark side adepts that might surround Obi - Wan, either as allies or enemies in his new dark side life.
Often, Obi - Wan uses his mastery of the Force. He might use a Force - push to overpower his guards when they least expect it and then make a run for it. He could also use a mind trick on a high - ranking captor to order his release.
Jon Snow could be one. He has a sense of honor and leadership, much like Obi - Wan. They could bond over their shared values and Jon could learn from Obi - Wan's wisdom. Another could be Daenerys Targaryen. She is on a quest for power and Obi - Wan might see her as someone who needs guidance to use her power responsibly.
He might have adventures related to understanding the unique culture of the all - female planet. For example, he could learn about their social structure, which may be centered around female leadership and cooperation. Maybe he would encounter some challenges in communication as their values and ways of thinking could be different from what he's used to in the Jedi Order.
Ezra Bridger would be a great character to pair with Obi - Wan. Ezra is still learning about the Force, and Obi - Wan could be his wise mentor, teaching him more advanced techniques and the true nature of the Force.