Petra was one of my least favorites among my team, but I did like her. She starts out as a noble in the Empire learning at the academy. Apparently she lived on an island vassal state that was recently conquered by the Empire.
She was a decent sword warrior on my team, but I usually sat her “on the bench” in favor of better fighters.
I did like her growth post time-skip. She grew up to be a very beautiful young woman.