Not really sure what you're asking here? Kreia is a Sith Lord who specializes in betrayal (hence Darth Traya).
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I think he means who is she, where did she come from, etc. While I don't know where she's from, I do know she was a Jedi Master (one of Revan's masters, actually). The Council acused her teachings of leading to Revan's fall and exiled her. She went to Malachor V (I think in search of Revan after the JCW?) where the power of the darkside there corrupted her. She later became the Master of the Trayus Academy and started the Shadow War against the Jedi, but was betrayed by Sion and Nihilus. Between that point and when you find her on Peragus, I have no idea. Most of this is probably wrong, my memory is a bit shoddy, so please correct me if I'm wrong.