Macoya
Macoya is a girl who's super smart, but she'll make you feel like you're the dumbest person in the class. She'll help you, but only if you help her.
Macoya helped me with my math homework, then made me do hers.
She said I was smart, then said I was the dumbest person in the class.
She helped me cheat, then said I was the worst cheater ever.