timdiggerm said:

Isn't part of the point of ROTJ that you're supposed to worry about Luke? If you don't, there's no tension in the Emperor's offer.

Luke's dance on the dark side at the end of RotJ is so convincing to me... that had Anakin's been remotely like it- had we seen something very similar, but one thing had gone another way... it would have amped up the tension for RotJ.

I'm sure Anakin turned to the dark side because he started doing a few bad things (wearing black, kissing his sister) but was still doing them for a greater cause (saving the galaxy, sounding like a separatist) to the point that no one, not even himself, was that aware of how vulnerable to the seduction of the dark side he had become.

That is how you should worry about Luke in RotJ. Luke's arc is like Orpheus- descending in to Hades to rescue a loved one without getting stuck there himself. And Vader is struggling with whether he will let Luke save him (can he be saved?) or go through with converting him.

When Luke lunges out at Vader and taps into the dark side long enough to defeat him, we shouldn't be too clear on who won the spiritual battle at that moment.