The irony is that if Lucas had allowed the ‘noble death’ of Han Solo, he would’ve had the answer to the ‘why does Luke snap’ conundrum. Vader/Palpatine could have been offering to halt the battle if Luke were to agree to turn (an actual temptation as opposed to simply making Luke mad) before Luke suddenly senses Han’s death through the Force. Luke kicks Vader’s butt and no-one has to be anyone’s shoehorned sister!
I had never thought of that. That definitely could’ve worked, and that might be a good idea for a fan edit that tries to kill Han and not make Leia Luke’s sister.
I definitely agree that it is kind of obvious that making Leia Luke’s sister was a noticeable last minute decision. But to play devil’s advocate, I do think making that change was a good decision in the long run. Family is obviously a central theme in the Star Wars films, and making Luke almost turn to save his sister’s soul does make that theme even stronger. Plus, it parallels Anakin’s own fall in the prequels, giving in to the darkside to save family, to save someone he loved.
And I do think you can make a fair argument about how Vader knew Luke was his son but never knew Leia was his daughter even though they had a few face-to-face interactions. But we never are really told how Vader found out Luke was his son. In the Special Edition of ESB, the Emperor tells Vader that Luke is his son, and he apparently had know idea before that. So he didn’t just sense it and figure it out. He could tell he was strong in the Force, but that doesn’t mean that he could since that he was his son.
For what it is worth, the new canon comics apparently explain this by having Vader piece different information together: Seeing that the rebel who destroyed the Death Star wielded his own lightsaber, learning that his name was “Skywalker”, and tracking down the mortician who was responsible for Padme’s burial and discovering that he was told to make her look pregnant, meaning that she had successfully given birth before she died.
Now yeah, “we shouldn’t have to read books to know this about the movies”, I agree, but I really don’t think the movies imply that Vader just “sensed” their biological relationship. I had always just assumed Vader somehow put two-and-two together in-between ANH and ESB. While I don’t think every little detail needs to be explained in the movies, I do agree that maybe it could’ve been set up better though, since this is a frequently raised up question. I guess it was just the best they could do with coming up with that decision so late in the game, but I do think it was the best choice in the long run.
I also am glad they decided not to kill off Han in ROTJ, because I think dying at the hand of his own son is a much more interesting way for him to go than any kind of sacrificial death he could have had in ROTJ, especially after the entire first act of the film was all about rescuing him. But that is just my opinion!
On the other hand, it could possibly have worked if Han’s sacrifice had been set up as crucial to the success of the Rebel’s mission, then it may have helped add importance to that first act, if that makes sense. It’s interesting to speculate on, for sure!