But how did he get to be Darth Vader? You have to explore him in relationships, and you have to see where he started. He was a sweet kid, helpful, just like most people imagine themselves to be. Most people said, “This guy must have been a horrible little brat – a demon child.” But the point is, he wasn’t born that way – he became that way and thought he was doing the right thing. He eventually realizes he’s going down the dark path, but he thinks it’s justifiable. The idea is to see how a democracy becomes a dictatorship, and how a good person goes bad – and still, in the end, thinks he’s doing the right thing.
George Lucas on Anakin [x]