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Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] What if Vader went with Ahsoka on Malachor?

After hearing his former Padawan promise not to leave him, Vader remembers all of the good memories he had with her as Anakin and comes back to the Light early for her. He is 100% dedicated to this, and doesn’t fall to the Dark Side again. How does this change the course of galactic history? Will he join the Rebellion? How does the crew of the *Ghost* react to him being on their side? What does Palpatine do?
gpt
If Anakin sticks, he has A LOT of Intel to help the Rebellion. He knows the Death Star is almost complete though not it's weakness. When Bail Organa finds out, once Bail is convinced that Anakin truly is back, he will consult with Kenobi to confirm.

If Kenobi is convinced, he will explain what happened with Padme, Leia, and Luke. This might also means Yoda is brought into the fold.

This has a bigger problem - Palpatine takes the Rebellion much more seriously. Before it was a few starfighters and barely an army. Now it has three Jedi masters, other Jedi Knights, and more coming. The extermination of the Jedi is critical to the Sith, so the Rebellion is going to have a much tougher time.