Charlotte is the first villian to come into the series and is the villian for season 1. She does die at the end of season 1, just letting you know so you are aware of that. She does need to sound like an adult, just say she's around 20-30. She also has her hands on nuclear weapons so.... Lets say she doesn't care if she starts a war and thinks she's stronger than everyone else, even though she isn't. 

Please sound as evil as possible and there is no need for any editing to make the voice sound more evil as she is just a simple woman who want's pretty much everyone dead.