Channel72 said:
But on the other hand, there is some evidence that Lucas actually decided that Vader was Luke’s father even before Leigh Brackett wrote the first draft. Kaminski points out how ridiculous this claim seems, because it means Lucas purposely withheld vital story information from Brackett, even while paying her to write the script (presumably out of paranoia of leaking the twist). And yeah, this does seem kind of ridiculous - but maybe it’s more like Lucas was just indecisive about the idea.
I’m thinking he hadn’t decided yet, as we have multiple accounts about Lucas taking his time to mull over where exactly he wanted to go with the character. The thing is, as far as Empire goes, whether the twist is there or not is just a matter of a few lines in a couple scenes near the end. All the real details about Darth’s past are handled in the third film. In their story conference they went over Darth Vader’s motivations and he even gave Brackett a treatment to work off of. I don’t think he wasn’t counting on her bringing in the ghost of Skywalker Sr, that seemed to be something she added on her own.
