"If you believe so." Vader clearly doesn't, and it only had some to do with Luke being his son, his child, and the age Vader had been when he Fell.

Vader had always been...sonewhat biddable on matters of morality, adapting to his Masters as a matter of survival, not that he had the self reflection to recognize the pattern.

"I want what I accomplished on Mustafar when I slew the Banking Clan leadership although with the free others who made up the Separatists Leadership." Their handsome reward, no longer handsome. "Peace, freedom, justice, and security to my empire. Palpatine however has other plans."