When I first saw ROTJ, I thought there would be just a bunch of wires and such behind Vader's mask. The ultimate mind f@$k and manipulation...messing with Luke's head the whole time about the father thing. Almost like Vader cyborg had been programed so well, it almost thought it WAS Luke's father.
I remember after Empire so many people just thought Vader was lying. I never understood that. No one would ever just write off a character -- especially Darth Vader -- and just have a big cliff hanger for an entire movie be simply a lie. Makes no sense. At the climax would he just be like: Oh you fool, I was lying. Too easy an out. I was intrigued just how they would handle the Luke thing. I thought he might go dark for a bit -- and actually kill Han Solo -- which would bring him back to the light. But as much as I wanted to see Han die -- and still think he should have died making a great sacrifice -- I can see why making Luke "bad" at any time would not have worked.
With the new films though, I may get my wish on both.