Many people still do not understand the Star Wars saga...

I suggest to all watching again the whole series and focus on all Darth Vader’s actions and words. He was actually The Balance into The Force, he was forced to join (briefly) with Emperor Palpatine, in order to bring down the Empire. His main goal was peace and be with Amidala… he knew also about the “other side” of the Jedi.

The Jedi and The Sith are just the today’s “left and right” political sides.

Darth Vader wanted Luke to join him into bringing down both sides and finally have the balance into The Force. Think again why Luke Skywalker after Vader’s death decided to isolate himself. He realized the mistake he did.