cap said:
They both know who they’re talking about, right?VADER: What is thy bidding, my master?
EMPEROR: There is a great disturbance in the Force.
VADER: I have felt it.
EMPEROR: We have a new enemy.
VADER: Yes, my master.
EMPEROR: He could destroy us.
VADER: He's just a boy. Obi-Wan can no longer help him.
EMPEROR: The Force is strong with him. The son of Skywalker must not become a Jedi.
VADER: If he could be turned, he would become a powerful ally.
EMPEROR: Yes. He would be a great asset. Can it be done? ( with the 2nd "Yes of course - Imp ;) )
VADER: He will join us or die, my master.
cap, I think it does depend on whether you think they both know who they are talking about before the conversation is started....or not. And whether the events seen and heard in the prequels muddy the waters a bit with the original dialogue....or not.
However, having thought about the original dialogue a bit more, and the exact order of each response said by both characters, I guess that Vader probably does know that the very Force-powerful Emperor has 'sensed' that it's actually Luke (who's Force-'influence' has increased greatly thanks to Yoda's teaching at this point in the movie) that has caused the "...great disturbance in the Force" that he's on about....before the Emperor goes onto confirm this disturbance is caused by "...Luke Skywalker" in his next response.
Going by his first response, I also reckon that Vader probably does also know that it is indeed Luke that is causing the "...great disturbance in the Force" too by now, even before he's contacted....and I think he probably KNOWS that the Emperor will believe that by now too, considering he knows how Force-sensitive Vader is.
Although Vader continues to respond 'grovellingly' with the "Yes, master" line as his answer to the Emperor's "We have a new enemy...Luke Skywalker", it could certainly be argued that this brief, 'submissive' agreement hides ulterior motives and he's waiting (and interested) to see what else the Emperor is going to go on to say about the matter before he says anymore himself.
So, as in your example above, I now agree that it could work equally well even if the Emperor DOESN'T specifically say something like "...Luke Skywalker" / "...young Skywalker" / **cough** "...the young rebel, Skywalker" **cough**, after he says "We have a new enemy". As I now agree that Vader probably DOES know who the Emperor is on about at the start of the conversation after all, and the fact it is certainly clarified by the Emperor during his later responses...then I guess It just becomes a 'stylistic' / 'does it sound better' kind of choice whether Adywan decides to 'emphasise' it during the Emperor's 2nd line or not. I'm not fussed as I reckon it works just as well either way now.
I also now think that the fact this dialogue and scene appears so late in the movie, doesn't conflict in any way with the fact that Vader (and by extension, the Emperor - it's his Fleet after all) is already looking for Luke from the start of the movie, whether just purely as part of the Rebel Alliance as a whole, since he's become a 'figurehead' for it, according to the 'intro. scroll'...nor even if Vader alone (or the Emperor too), had 'seperate agendas' from the start of the movie where Luke's 'possibilities' were concerned. It's only because of Luke getting VERY Force-powerful by this stage of the movie that brings about this particular conversation about his potential danger to their Sith setup, no matter what they may have discussed in the past about going after him or not.
The original dialogue can be seen to work well as a case of 'misdirection' and 'gamesmanship' between the two, despite the prequel events. So no "How is that possible?" question needed from Vader after all, to upset the applecart of what he wants the Emperor to believe at this point (his unwavering loyalty and agreement), for the sake of trying to tie things together. The original dialogue can still be seen to make complete sense without any rearranging or retconning for the prequels as the SE attempted misguidedly to do.