Gracie

Gracie is another member of the Infinite Five, known as the "wildcard" of the team. She's typically a polite, well mannered young lady, but can be quite flippant and absent-minded. However, she's capable of switching completely, and becoming sadistic and calculated, making her a feared member of the Infinite Five's roster, mostly due to her unpredictability.

She should have a normal female voice, but you should be able to shift to a different pitch drastically, as Gracie is known to be temperamental and flip out completely incredibly easily, hence her title of the 'wildcard'.

(If I had to compare her personality to that of any existing characters, I'd say Spinel mixed with Nui Harime)