But I do think you get a fairly similar dynamic from the prequels when you look at it from the perspective that Anakin embraced evil after falling down a slippery slope of good intentions that left him feeling like he couldn't go back.
I mean sure he starts out ESB looking for Luke with the intention of overthrowing the Emperor, but it was only to replace Palpatine as dictator.
He had gone to the dark side to save Padme, and it cost him his very humanity. After she died all he cared about was controlling the galaxy to make it the way he wanted it to be. He became more machine than man, even his thoughts were mechanical and without heart.
So then Luke enters the picture and shows Anakin an example of love and compassion that wakes up that spark that starts to grow inside Vader's helmet until he finally does the right thing at the end of ROTJ.
I personally like it better with the idea that Vader and the Emperor are so evil, they can't trust each other.