This sounds like a reasonable beginning, though it's not what I would have done. It's still just a background, isn't it? I mean, who is the central PC in this plot?
Also, Revan left the republic a year after the events of K1, which means that by the end of K2, he has been gone for over four years. That's a pretty big gap to fill with just an explanation of him being captured by the true Sith.
And then there's the question of why they leave him alive. Revan is a great threat to the true Sith, so leaving him alive, even as a prisoner, really just gives him the option of escaping later (sort of like all the villains in the Bond movies, who always tell him all their plans, then leave him to die instead of just putting a bullet in his head and get it over with...)
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Yes, this is all just an introduction , think of it as filling in the gaps. It's a bit of backstory. You'd go a new main character in K3. I'll post more of my story later... Oh, and the reason why they kept Revan alive is to use him/her as bait, to draw out his/her allies into the unknown regions and be destroyed by a weapon that they've been building for centuries.
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And that weapon is living, yes?