system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] Why would Luke have turned to the dark side had he killed Palpatine, but Vader turned to the light side when he did so?

Palpatine had to die either way in order for the Empire to collapse, so what difference does it make by whose hand?
gpt
Striking him down in anger vs getting rid of him out of love (for his son), sacrifice (being electrocuted) and because it was the right thing to do.

The emperor goaded Luke into attacking him out of pure hatred and disgust, which is how the Dark Side manifests itself.