All three of these characters are in a sense misfits in the community of Shady Hill. While the world of Shady Hill, an affluent suburb of New York, is one concerned with maintaining an affluent WASP ethos, focusing on good manner, understatement, not making waves, and preserving a smooth, untroubled facade, all of the three characters for different reasons are uncomfortable with that environment and the social strictures it imposes on them.
Francis Weed has (temporarily) be changed by a life-altering experience: being in a plane crash. This makes him desire to have a more authentic life, and although he eventual settles back into his traditional role, over the course of the story he is acutely aware of the inauthenticity of life in Shady Grove.
Clayton is a cynical teenager who considers the community of Shady Grove "phony." The death of his father and his family's lack of money both make him an outsider.
Gertrude is also an outsider who wanders from house to house and quietly observes the activities of the adults in Shady Grove without participating in the community ethos.