MEAN GIRLS 1: The Noble Wicked

Nicasia Donovan was raised to be a kind, noble, prim and proper type of lady. She's always an outcast but it ever bothers her. She'd rather be alone than make friends who will betray her. She's too young to explore but all of it faded when she met her second family, her step sister particularly. How come did the noble princess become the noble wicked?