@Mrs.peacock said:

In ROTS Sidious tells Anakin the only way to save Padme from death is to join the Sith after Padme dies, Sidious tells the newly minted Vader that he, himself killed her. So why would he remain a sith? What motivates him to evil when the driving force of that decision is taken away?

This is the reason i maintain that Revenge of the Sith is a horrible movie.

I see you've taken the high ground there...

@Mrs.peacock said:

In ROTS Sidious tells Anakin the only way to save Padme from death is to join the Sith after Padme dies, Sidious tells the newly minted Vader that he, himself killed her. So why would he remain a sith? What motivates him to evil when the driving force of that decision is taken away?

Based on a passing knowledge of the Clone Wars cartoons, a little bit of knowledge of a couple comics, and a slipshod recall of the prequel trilogy, I'd say that he really had little else going for him, at that point.

He sought power in order to save his wife (likely engineered by Palpatine, and never a true threat). He ultimately failed to save her, by which point everything he knew in life had just been destroyed by the person to whom he'd become beholden. It isn't shown in the movies, but he had recently come to find out that the Jedi had been keeping a secret "black site" prison for people who were "too dangerous" to try in open court. The Jedi, in addition to being blinded by the dark side by the war that Palpatine orchestrated, were becoming corrupted over time. They were acting a lot like a major world government in our present day - which is to say, unworthy of trust. The movies did show that they asked him to spy on the duly elected leader of the Republic, which is political espionage, coming from a supposedly apolitical group. Not only is that shifty, but Palpatine had long since ingratiated himself as Anakin's mentor, which was in turn a clever way of making Anakin fail to see Obi-Wan as his mentor, which a Jedi padawan certainly should.

Yet, Anakin would seem to have thought that he had some form of responsibility in the shaping of things in the galaxy, by virtue of the fact that he was extremely powerful. He also seemed to want to exercise that power to make things "better" to his own way of thinking (wanting to save his mother, wanting to free the slaves on Tatooine, wanting to maintain "order in the galaxy," etc.). That sounds to me like a form of helping other people, whether or not it would really work out in the long run.

Looking at it from Anakin's presumed perspective, he had all these ideas about how he was going to become powerful in order to help his friends and family. Then, his friends all betray him (according to his point of view), his family all dies, and the Republic which he was sworn to serve is replaced by an empire. How does one go on with their life? All he'd really have left to him, then, would be the sense of wanting to make things better, maybe a little corrupted by a jaded sense of loss or purposelessness. What would you do, other than continue to serve the person who had promised to help you save your late wife (that you believe you accidentally killed)? The person who had shown you that your friends had been violating their own religious moral code, and lying to you about it, as well as trying to stage a political coup? He could not ignore the fact that his immense power could still allow him to maintain order in the galaxy, by any means necessary, in order to create a stable, secure Empire which would provide for a way of life for untold numbers of lifeforms. Running back to Tatooine to live as a hermit would have been too irresponsible for Darth Vader's sense of needing to help people.

Even as Darth Vader, he probably had a twisted way of looking at everything he did as being for the greater good. By the end of Revenge of the Sith, there was really little else he could do, than to follow Palpatine.

Edit: Spelling is hard.

I agree with others that his motivation wasn't sufficient. The problem with so many villains is that they're treated without any sense of humanity. Hitler, for instance, was a failed artist and a deeply insecure human being. He had a remarkable talent for oration that brought him to power, where ego drove him. A sociopath, he had no issue using lies and violence to reach his goals. He was monstrous because his overweening ego had to be fed but he did care for his dogs and mistress, so he wasn't inhuman but rather intensely selfish and indifferent to the suffering of those not in his orbit.

I'd always wished Lucas had given the germ of his ideas to superior filmmakers who could have fleshed out the character and given him more humanity. Kirchner did this for Empire, creating living, breathing people in Luke, Leia, and Han where archetypes had only been in Star Wars. Vader should have loved Padme, sure, but he should have been a much more intense, volatile character. She should have had reason to fear him, though she loved him, which would have motivated her to hide her children from him at the end. And he should have been deeply mistrusting of not only that relationship, but also of the Jedi. (It would have been nice to see the Jedi a bit like the way The Boys treats superheros ...as flawed, egotists but with some great members like Obi-Wan and Yoda working to check their excesses.) Many who have a power granted to them, but which wasn't earned, treat it like a right and not a privilege.

Sadly, all water under the bridge. Vader stayed Vader because he had to, not because it made sense.