Why a Sith Avatar?
Before anyone goes off on the usual Jedi propaganda rant, I'd like to point out that the whole damn Jedi order presided over a 5-millenium "republic" with zero innovation, and rather a lot of slavery. The Sith by contrast - an organization consisting of two people - pushed massive technological leaps in one generation. Of course the only ones you hear about are clone troopers, star destroyers and death star(s), and lightsabres other than a single blade, but which side is writing those movies? Also: think of the peacetime applications! Cloned organs, cities in space reducing ecological footprints (do you want your planet to turn into another Coruscant?), and the ability to supply the entire galaxy with its mining needs with just one planet blown up every decade or so! Oh, and lightsaber-based food processors and lawnmowers.
And you can join at any age, and are allowed to love.
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Actually, the non-satirical reason is that I can project myself onto a fictional character who is moved by her shadow, in touch with her id. Playing KOTOR, I realized that Lucas's good vs. evil barely holds up if you take long enough to think about it, and the Jedi are better at looking good than doing good. They are incapable of making real change. They are feel-good in-activism presented as glory. They are the state's dictum that legitimate agency in opposition to injustice starts at calm dialogue, moves into sign-carrying, and stops at passive resistance. All other forms of making change have been ruled out, cast into the shadow.
From there, both personally and politically, in projecting myself onto the "bad guy" within this narrative context, I can enter into dialogue with the parts of myself forced out of conscious acceptance (i.e. into the shadow), weigh them and give the parts that I like time to develop within a safe fictional shell. I do this with larp characters, and can separate those impulses which I fear into those I have and can/should use, those that I have and should only direct outwards when in a safe place while keeping in compassionate awareness for when I see other people living them, and those which I merely fear that I have. From this, I have learned: I can present in a dorky feminine fashion without the world ending; had, in the past, survivor guilt that I needed to acknowledge; I intuitively understand why people would submit to a tyrannical regeime but should only exercise that in my actual politics so as to fight that impulse in real life; and am basically, even when playing an awful person, motivated by fixing the world.