ReadingRambo
Member
Who Vader? They keep goading him to strike at the emperor and let his emotions take him over to the dark side. He knows he won't fight his father so the deflection by Vader works to re-direct his anger to him but Palpatine needs Luke to kill his father in order to firmly push him to the dark side. I feel like killing Palpatine would have started him on that path though maybe not with as much finality as with Vader. Thus Vader stops him to save his son..
Maybe
I would like to think so.
But if that was Vader's goal why wouldn't he just kill the Emperor himself right then and there?