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human
[Star Wars] Why was Luke able to bring Anakin back to the light when Ahsoka couldn’t?

We all know the story. After finding out Vader was his father and resisting the dark side, Luke Skywalker managed to bring Anakin back into the light. Son redeems father. Galaxy is saved.

Here’s my question: why was Luke able to sway Vader when Ahsoka, his former apprentice, couldn’t? In Twilight of the Apprentice the two face off. Ahsoka tells him she won’t leave him again. Vader is silent for a moment, perhaps torn by what she’s saying, but ultimately doubles down on the dark.

So what gives? Luke is obviously Vader’s son… but Ahsoka was like a little sister to him. Luke had more time to try to convert Vader. If Palpatine had zapped Ahsoka, would Vader have been swayed and acted as he did with Luke? Or did it have to be Luke, specifically, that saved him? If so, why?
gpt
Ahsoka, as a Padawan who left the Jedi, is a symbol of Anakin's failures. Luke even existing, on the other hand, is a positive reminder of his successes; the exact sort of thing to break the loop of fear and torment that Palpatine had stuck Anakin into.