Qu isn't pure evil, she just doesn't have much self control. Or any, for that matter.
[hider=Regarding Balance/Technicalities]Qu is literally just a complete bother. While she is a character who is not extraordinarily dangerous, she's annoying to have around and extraordinarily difficult to get rid of. She is not completely invincible, but she's close enough that it's not conceivable for any single foe to be able to defeat her head-on. The fake Qu becomes distorted when the true Qu uses its abilities, making Qu vulnerable to attack. Additionally, if she is sufficiently hurt, she cannot just revert back to the fake Qu to avoid danger. Her biggest weakness is her personality, as she is both easily distracted and easily tricked. She isn't completely stupid, just easy to manipulate.

Oh, and she is actually a Titan. The fake Qu qualifies as a Titan both in back-story and body, and as she is an extension of the true Qu, the title applies to both of them.[/hider]