Are you Dona? She's not really a bad guy, though she does act like a jerk to Yuna, but her goal was to bring peace to Spira by bringing the Calm...so that's my reasoning!
Yes!
Well done Avec, I didn't think anyone was going to get it. I've realised X is a really good game to pull characters from, because there are a lot of semi-important NPC's that play memorable roles, her being one of them.
You came close with your previous guess too, but I didn't want to point that out incase it made it too obvious XD.
So, Avec's turn
EDIT: Also, my "...no" response to the "are you a bad guy" question was a clue, so I'm glad you caught that too
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