Well you can over think it. . .and perhaps Fabio is
, but at the very basic level, I think the general actions and motivations of characters in the original trilogy can be explained in a way that makes sense and doesn't require you to make many logical leaps. Vader's actions don't seem that odd to me.
I do have a harder time understanding some of the characters' motivations and behaviors in the prequels. And I think the biggest part of that is Lucas kind of losing it, and being motivated more by commercial interests than creative ones, but I think another part of it is due to the convoluted nature of the films. It's pretty hard to keep track of what is going on, who is where, even which characters are supposed to be important at a given time. When Lucas has to concern himself so much with trying to make a coherent narrative out of all that, I can see the actual characters themselves being a bit of an afterthought.
