What does Hillari's behavior at the ball tell you about her as a person?

Hilliari exemplifies the attitude of "it's all about me". She wants to be the center of attention at all times, to be admired.... to be envied. When Stargirl garners all of the attention at the ball, it's Hillari's turn to be jealous, and her jealousy, which prompts her to slap Stargirl, exposes who she really is..... a completely superficial person.