The meaner Hillari is, the nicer Stargirl appears. And the kinder Stargirl is, the more truly awful Hillari seems. This is a classic foil, folks. Stargirl's and Hillari's main characteristics help to highlight each other in the back and forth between the novel's biggest bully and the novel's hugest heart.
Let's face it, folks. For the most part, Wayne just breathes and looks good. He doesn't do anything. He's dull. Enter Stargirl, who is the complete opposite. She is full of life, involvement, and connections. She is vivacious, shiny. Even her name conjures up images of shininess. The more she shines, the more Wayne appears in serious need of some polish.