Darth Tremor said:
Though I still like the idea of Palpatine using lightning on Vader to make him submit to the dark side, it would add gravitas to Vader’s line, “you don’t know the power of the dark side! I must obey my master.” You would then understand Vader to basically be saying, “I obey or die,” that he lives under tyranny.
However that is something that could be achieved, or at least hinted at, through fan editing. There is a moment after Anakin’s turn, before Palpatine tells him to rise, where we cut away to Yoda feeling the catastrophe through the force. One could add Palatine raising his hands and shooting Anakin with lightning just before the cut, continuing the sound effect through Yoda’s moment, add an evil laugh for the atmosphere and return to palatines office, where Anakin thanks his new master. This would retexture the function of force lightning, not just as a weapon but as a tool for control and dominion, essentially like a burn sign. It would show how Anakin is broken after his betrayal. He is paralyzed by his dependence on Palpatine, induced by his fear of loss. Furthermore he might very well want the punishment as a mean to numb his conscience, after all he just unleashed the ultimate horror on the galaxy.
I think something like that could serve the function of reinforcing Vader’s line in episode six, unless I misread your meaning here.
On an unrelated note. It just occurred to me, that Anakin’s redemption, which is essentially tied to the birth of the twins is ultimately dependent on Obi-Wan winning their duel on Mustafar.
That does not fit with an redemption arc, because it is no conscious decision to do good, which would signify hope for him. Instead it is his overconfidence to get the jump on his former master, which allows Obi-Wan, the droids, Padmé and by extension the twins to escape.