Their relationship could be shown as very conflicted. Darth Vader is deep in the Dark Side, but Ahsoka still remembers the good in Anakin. She might be angry at what he has become, while also feeling a sense of pity. Vader, on the other hand, might see her as a reminder of his failure as a Jedi.
In fanfiction, their relationship could be a journey of self - discovery for both. Ahsoka could learn more about the Dark Side through her encounters with Vader, and Vader could be forced to confront his past actions towards her. They might have intense lightsaber duels that are also a form of communication, with each strike and parry saying something about their relationship.
The relationship in fanfiction could be one of reluctant respect. Despite their differences, they both know the power of the Force. Ahsoka might respect Vader's strength in the Force, while Vader could grudgingly admit that Ahsoka is a worthy opponent. This could lead to some interesting scenarios where they are forced to work together against a common enemy, even if they don't fully trust each other.
One way to further explore their relationship is through the Force. Since they are both strong in the Force, they could sense each other's emotions and intentions from a distance. For example, Vader might feel Ahsoka's determination to stop him, and it could remind him of her as a young Padawan. Also, a story could be written where they communicate through the Force without actually meeting, sharing memories and feelings about their past together.
In many fanfictions, their relationship develops in a complex way. At first, it's mainly about the enmity. But as the story progresses, there could be moments of understanding. For example, Vader might see some of his old self in Ahsoka. Ahsoka, on the other hand, might start to pity the broken man that Anakin has become. This could lead to a strange sort of respect between them, even though they are on opposite sides.
In a fanfiction, Darth Vader might finally face his past with Ahsoka. Maybe he would have moments of hesitation in their battles, as memories of their time as master and apprentice resurface. This could lead to an internal struggle within Vader, torn between the Dark Side and his former self.
Ezra's reaction would also depend on his state of mind at the time. If he was feeling confident and strong in the Force, he might be more bold in his approach to Vader. He could try to engage in a battle of wills through the Force, trying to push back against Vader's dark side influence. But if he was already weakened or doubting himself, the sight of Vader could make him feel hopeless and desperate, leading to a more erratic or panicked reaction.
In a fanfic, it's really up to the writer. However, considering their abilities, Vader is extremely powerful with the Force, but Ahsoka is very agile and has unique fighting techniques. If Ahsoka can use her speed and agility to her advantage, she might be able to outmaneuver Vader. But Vader's brute strength and experience in combat are also not to be underestimated.
In fanfiction, their duel could be more about psychological warfare. Ahsoka might use her knowledge of Anakin to try and get into Vader's head, making him question his loyalty to the dark side. For example, she could bring up memories of their time as master and apprentice. This would add a layer of complexity not always seen in the official duels.
Well, a cool plot might be that Ahsoka gets trapped in a Sith - created illusion world by Vader. In this world, she has to face her past traumas and fears related to Anakin's fall. Meanwhile, Vader is conflicted as he watches her struggle, memories of his past with Ahsoka resurfacing. Or there could be a story where they both are on a mission to retrieve a powerful Jedi/Sith artifact, and their paths cross in a race against time.
One of the most dramatic encounters could be their lightsaber duel. The contrast between Ahsoka's acrobatic and precise style and Vader's brute force is intense. Their duel is not just about physical combat but also about the ideological clash between the Jedi and Sith. Ahsoka represents the hope and the Jedi way that Vader once knew and discarded. Another aspect could be the moments of silent confrontation, where their expressions and the Force around them create a palpable tension.
In a fanfiction battle between Ahsoka and Vader, it's really hard to say who would win. Ahsoka is highly skilled and has a deep connection to the Force. But Vader is extremely powerful with his Sith abilities. It could go either way depending on how the writer wants to portray it in the fanfiction.
In Star Wars Rebels fanfiction, Anakin is often portrayed with a mix of his former self and the Vader persona. His fall to the dark side is still a big part of his character, but his love for Ahsoka can shine through. Ahsoka, on the other hand, is usually depicted as a strong and independent Jedi. She has grown since her time with Anakin and is more in tune with the Force. Their interactions in fanfiction can range from tense, due to Anakin's past actions, to warm and nostalgic as they remember their time as master and apprentice.