Gaffer Tape said:
One might argue that he had character development occur offscreen in between Star Wars and ESB when he finds out that his son is alive and working for the Rebels.
Ok lets argue!
In ESB there is no certainty that Darth Vader is Lukes Father - In the original theatrical movie which is the only version that counts untill, Adywan releases his!. There is no character development of Darth Vader happening off screen or otherwise... as a character he just wasnt designed like that - he is purely a villain - he starts off a villain and he ends a villain. All the crawl says about Luke and Vader is that "Vader is obssessed with finding Luke Skywalker" nothing else..... During the conversation with the Emperor, Vader never refers to Luke as his son. (remember at this point, all the audience knows is that Anakin Skywalker was killed by Darth Vader).
During the fight with Luke....he tells Luke hes his son....but i dont think anyone really believed that untill return of the jedi was made. So i wouldnt call it proper character development. It is certainly character Development for Luke because what Vader say's has some emotional impact on him.....but Vader is unchanged by anythning that happens here.
previously i said that Darth Vader's character development is him being redeemed.
But now i think his whole character development for Vader begins - when Luke surrenders to the imps and they are brought together again. Then Vaders character does start to change....