The Boy in the Bubble — Zetta Elliott

A mysterious boy from another planet chooses an unusual girl as his guide on Earth. Both children lead solitary lives: the girl lives under a rock and lives on a diet of dreams; the boy, encased in a bubble, is unable to touch--or be touched by-- anything around him. As their friendship develops, however, the mysterious boy and the unusual girl begin to recognize the limits of their sheltered lives. The two children quarrel, but ultimately they find a way to shatter the bubble that separates them from one another and the world.