Originally posted by: Wesyeed
So I conclude that Vader, in some way, was warning his son about his master and what he can do to him, both mentally and physically, as it was done to him at his age.

that made me think of something. Vader/Anakin doesnt help his son until he sees Palpatine using the Lightning on him. Think maybe he realized that way back in the day when he was turned to the dark side, that maybe he didnt need to jump in to help out palpatine by cutting off mace's hands, think maybe it was just then he realized he was duped into 'rescuing' palpatine, who really didnt need to be rescued. hence why he decided to stop palpatine from zapping his son and toss him down the shaft.

just a thought.

-Darth Simon