Mia Mueller is the daughter of Peg Mueller and the best friend of Andie Bates. Like her mother she is also a witch but her magical abilities are barely developing. She has been secretly taking lessons from Devon. However after discovering that her mother knew Andie is succubus and didn't tell her she turns to Devon for more help.(Dog Eat Dog).
Mia is a very smart girl. She is on the Academic Team with her best friend Andie. She really likes science but her competitor is . She created a lie detector for the school fair that, ironically, united Andie and Charlie. Like her mother, she is very wise and calm while giving Andie advice about her relationship with Brett and Charlie.