There are also fanfictions where their relationship is more complex. For example, Vader might capture Ahsoka but instead of killing her immediately, he keeps her prisoner. During this time, they have many conversations that make Vader question his Sith path, and Ahsoka starts to see the remnants of Anakin in him. This leads to a slow and tentative re - connection between them.
Many fanfictions explore the idea of a post - redemption relationship. If Vader were to be redeemed, how would he and Ahsoka interact? They might become like siblings again, with Ahsoka helping Vader to fully embrace the light side once more and Vader using his newfound perspective to help Ahsoka in her Jedi journey. Their relationship would be one of mutual growth and support.
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.