Nine-year-old protagonist Peter Hatcher is an intelligent, analytical, self-disciplined fourth grader. As the book’s first-person narrator, he relates all events from his fourth-grade perspective. His younger brother, Fudge, is a toddler and constitutes the most serious source of stress in Peter’s life. High-spirited and occasionally rambunctious, Fudge receives the largest share of the Hatchers’ parental attention. Consequently, Peter often feels unappreciated and unloved by his mother and father. Nonetheless, he is very mature for his age and often functions as a younger parent figure for his brother. His overwhelmed mother frequently asks him to assist her in caring for Fudge—like standing on his head to persuade Fudge to eat—and Peter always complies with her requests.

While he feels all the normal resentments of a first child displaced by an attention-grabbing toddler, Peter does have an innate affection and true sense of responsibility toward his sibling. When the child calls to Peter from the Central Park jungle gym, declaring, “Fudgie’s a birdie” (36), Peter dashes over in an effort to rescue him. When Fudge ingests his brother’s beloved pet turtle, Peter is infuriated and desperately hurt. Nonetheless, while waiting for news of Fudge’s condition at the hospital, Peter reflects, “Maybe he wasn’t such a bad little guy after all” (116).