OK, this is meant as an antidote for certain recent stupid posts...
I was reading a historical novel recently (don't ask, you don't know it anyway, albeit it's written by Nobel prize winner) and I thought that the problems the main hero faces could be neatly used in script for Anakin's turn to dark side. (because most of us agree this was one of the weakest thing executed in Ep.III).
Meet Andrew K., a young, brave man full of vigor. It is the time of war - his country faces multiple threats, including internal ones.
Even though he served his duty and that all odds are against him (his country's forces are in retreat), he gathers a team of soldiers who know no fear to make a series of "hit & run" raids on the enemy.
His skills can't go unnoticed. A powerful aristocrat asks for his support and wants him under his wings. The young man sees this as an opportunity (I'll skip all the legal problems which all would be instantly solved by this alliance ;) ), and the old nobleman wants a man with such bravado on his side...
In the meantime a new, powerful enemy attacks the country and makes unprecedented and unexpected progress. Province after another fall into its prey.
The old nobleman ask the young hero to swear, that even in the worst of times he won't leave him. Our patriotic hero zealously agrees, as he fears no enemy and will fight even a lost battle for his country. The old man is very pleased...
During a great party with other commanders and nobles, the old aristocrat announces that... he joins his forces with the invading enemy!
Our hero is shocked... just as are some other commanders, who refuse the oath of obedience to the new masters.
...to make things worse, our hero is given the task of... subduing the "rebelling" troops.
His conscience is soothed, as the old aristocrat explains him his complex plan: he doesn't really join with the enemy, he just want to save his province/troops/resources from the pillage, wait for the moment when the enemy is exhausted by the victorious, yet long campaing - and then to strike to liberate the whole country.
So with the new energy he quells all "nay sayers" who are in fact faithful to the country. But he is convinced that the country is doomed with its current leadership, and that only the plan of his old master may be the only chance to defeat the stronger enemy.
As he was always zealous, he's fulfilling his task with great energy... and ruthlessness. In his eyes - and according to his master - those patriots are traitors!
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Of course he later finds out that the old aristocrat does this only to gain power - at any cost. He changes sides again, trying to repair all the damage he had done to his country. But that's another story...
What I wanted to say, I didn't want Vader to be a whiny youngster full of angst and fear, killing bunch of children when his mood changes. I wanted him to fall in the trap many countries do: the government doesn't want to negotiate with the rebels/rioters, no matter how good are their reasons, because "there must be order" - and sends troops to quell the uprising. People get beaten or killed. In revenge, the rebels/rioters strike at the government, blowing up sth, then they are called terrorists and treated as traitors, even though they may be true patriots and it is the government who went too far.
Vader should be ultra rightie :D At first he looks like a good guy: patriotic, church going, full of zeal. But his good zeal turns into hatred towards anything that his leaders say may be against things he believe. Even if he - at some point - realizes that things went too far, he only reinforces himself in his resolve, unable to admit "they have lied to me and used me as a tool for their evil schemes, because they saw my unbroken faith".