At first, Atris largely struck me as being your typical sanctimonious jedi.

 

Now, with the revelation of the cut content, we know she was the other candidate for Darth Traya, which, from the revealed content in the ending, makes perfect sense. She viewed the Exile as betraying the Jedi and her personally, so she betrayed the Exile in turn. Since Kreia described Darth Traya as "one who was betrayed in their heart, and one who will betray others in turn," it works for Atris better than Kreia. We know Kreia was betrayed by Nihilus and Sion, but she was already Traya then. I guess she views herself as being betrayed by Revan, since Revan was a "paragon of the order" (till Revan found out about the "true sith") and it's clear that Kreia never wholly agreed with the order. However, with the revelation Kreia wants to kill the force, she seems to fit the title of Darth Nihilus better than her paper tiger of a student.

Atris really bugged me as a character. She was a b1tch, quite frankly. She was weak, frightened, and spat out bile for those that she secretly envied. Add to that she was delusional. Her revelation of corruption was poorly played out, and she was never really redeemed as a character. Luckily she was never the anchor to the story.

Would you think the same thing if she came with you. This is a pretty big "what if" but what if she made it clear she didn't think much of you, but after getting one Master she decides to join you. So I guess she becomes the nagging Bastila of the group...

but then again if that happened I would've been satisfied she wasn't a wasted a character and this wouldn't even exist - unless it was a petition for an improved model.