It could be different in that the setting might be more unique. Instead of the typical Star Wars battle arenas, they could be fighting on a planet filled with strange Force - influenced creatures. These creatures could either interfere in the fight or be used by one of them as a weapon or distraction. Also, the duel could end not in a clear victory for one side, but in a stalemate where they both realize they have more in common than they thought.
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, in fanfiction their duel might involve new Force abilities. Ahsoka could have developed some new techniques during her time away from the Jedi Order, and Vader, with his connection to the dark side, could also show off some previously unseen powers. The fight could be less about brute force and more about who can outwit the other with these new abilities. Maybe Ahsoka uses a new form of Force - projection to make Vader think she's in multiple places at once, while Vader tries to counter with a dark - side - powered illusion of his own.
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 some fanfictions, their relationship is very antagonistic. Darth Vader sees Ahsoka as a reminder of his failed Jedi past and wants to destroy her. Ahsoka, on the other hand, is determined to stop Vader's evil deeds.
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.
A really exciting plotline might involve Ahsoka getting trapped in Vader's memories. She has to navigate through his past, seeing his fall to the dark side and his relationship with Anakin Skywalker. This could lead to some very emotional and thought - provoking moments as she tries to understand him better and perhaps find a way to save him.
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.
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.
One scenario could be that Darth Vader discovers Ahsoka is still alive and is conflicted between his Sith loyalty and his past connection with her. He might secretly try to protect her from other threats in the Empire without revealing his identity.
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.
It could explore their relationship by showing the contrast between their current selves. Ahsoka is a free - thinking Jedi - like figure, while Vader is a servant of the Emperor. Their relationship could be one of enmity, with Ahsoka seeing Vader as a fallen hero and Vader seeing her as a nuisance to the Empire.
If Ahsoka joins Vader in fanfiction, their relationship would become extremely complex. At first, it would likely be filled with anger and resentment from both sides. Vader might see her as a reminder of his past failure as Anakin, and Ahsoka would see him as the fallen Anakin she once knew.