Who is Ginnie Maddox from Nine Stories and what is their importance?

Ginnie Mannox is a teenage girl who comes from a wealthy family, lives in Manhattan, and attends a private girls' school with Selena Graff. Ginnie is resolute and resistant to manipulation, yet, she is sometimes manipulative herself. Over the course of the story, she becomes enamored with Selena's brother, Franklin. Ginnie is the only character in this collection whose inner thoughts are described by Salinger.