She changes it a great deal. For starters, the gender difference can bring in a new type of relationship. Instead of the more traditional male - male rivalry, there could be an element of attraction or different kind of respect. Also, her way of handling the Force and Jedi teachings might be different, which would affect how Vader reacts to her.
One interesting idea could be a female Obi - Wan being a mentor to a younger generation in a different way than the male Obi - Wan. She might use her unique perspective to train Jedi. As for Vader, a fanfiction could explore his relationship with this female Obi - Wan in a more complex way, like they have a grudging respect for each other's skills.
One possible plot could be that Vader, without his suit, is found by Obi - Wan in a hidden location. Obi - Wan, despite their past, decides to help Vader recover. As they interact, they start to understand each other's perspectives better. Maybe they even form an uneasy alliance against a new common enemy in the galaxy.
Their relationship might start with suspicion. Obi - Wan would be cautious as he's seen Vader's evil deeds. But as Vader is suitless and perhaps more 'human' in a sense, Obi - Wan could start to see the Anakin he once knew. This could lead to a slow rebuilding of trust.
Well, in a lot of fanfiction, the female Obi - Wan is characterized by her grace. She moves with a certain elegance, whether she's in a lightsaber duel or just walking around the Jedi Temple. Her fighting style might be more fluid compared to the male Obi - Wan in some interpretations. Also, she can be more in touch with her emotions while still maintaining her Jedi discipline. This allows her to form deeper connections with other characters, which in turn affects the story's plot and her character development.
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.
In the fanfiction where Darth Vader travels back in time, his bond with Obi - Wan Kenobi would be full of possibilities. Imagine Vader going back to a time when he was still Anakin. He might have a newfound respect for Obi - Wan, knowing all that Obi - Wan tried to do for him in the future. Obi - Wan, for his part, could be shocked to see this changed Anakin. They could form an alliance against the emerging threat of the Sith, or Vader could try to get Obi - Wan to understand his view of the Force. Their relationship would no longer be simply that of a Jedi and his fallen apprentice, but something far more nuanced and unpredictable.
One common theme is a different take on the Jedi Code. With a female Obi - Wan, writers might explore how she interprets and perhaps bends the rules in a way that a male Obi - Wan might not. For example, in some stories, she may have a more emotional connection to certain events or characters, which could lead to different decisions.
In such fanfiction, female characters are often strong - willed. For example, they might be determined to prove themselves in the Jedi Order like Obi - Wan. They can also be highly empathetic, using their emotions to connect with others in a way that complements Obi - Wan's more stoic nature. Another characteristic is their intelligence. They are usually quick - thinking and able to come up with solutions to problems, just like Obi - Wan himself.