@ Xanatos - You make a good point, that if in fact she has no backstory, then she would seem rather lame. The fact that they so blantantly leave out any backstory for her though only adds fuel to the theory that she is Rinoa, which if true would provide an amazing backstory. But as noted there's no concrete proof, but with no other story to plug in for her, there seems to be a major void in the game as you said.