Peter is a twelve-year-old boy entering the seventh grade. He serves as the oldest child in the Hatcher family and frequently finds himself managing his younger brother's chaotic antics. Highly self-conscious, he worries deeply about public embarrassment and what his peers think of him. He is fiercely protective of his siblings and loyal to his friends despite his frequent exasperation.

Fudge is the exuberant five-year-old middle child of the Hatcher family. He recently developed an intense fascination with money, constantly talking about his plans to get rich and printing his own currency. He can be demanding and oblivious to social boundaries, but he is also highly imaginative, sensitive, and deeply attached to his family and pets.

Warren and Anne are the parents of Peter, Fudge, and Tootsie. Anne works as a dental hygienist and prides herself on calm communication, while Warren works in advertising and takes a slightly sterner approach. They try to remain patient and positive, but their limits are tested by Fudge's obsession with money and the unexpected arrival of their relatives.

Howie is Warren's long-lost cousin, a boisterous park ranger who recently moved his family from Hawaii. He holds strong, unconventional opinions about parenting, forbidding television and sugary foods in his household. He deeply values family connections but remains oblivious to the discomfort his loud personality causes others.

Tootsie is the two-year-old baby sister in the Hatcher family. She is curious and active, occasionally serving as the star of an art show featuring her painted footprints.

Jimmy is Peter's longtime best friend. He lives with his father following his parents' divorce, and he anticipates significant life changes as his father's art career takes off. He struggles with the anxiety of moving and his shifting family dynamics.

Mr. Fargo is Jimmy's father, an artist who has recently begun to achieve financial success. He is dating a new woman and planning to expand his family's living situation, bringing both excitement and stress to his son.

Eudora is Howie's pregnant wife. She follows her husband's strict lifestyle rules but occasionally reaches her own limits regarding his inflexible expectations while staying in a cramped New York apartment.

Flora is one of Howie's twin daughters. She is homeschooled and performs alongside her sister as one of "the Heavenly Hatchers." She is oblivious to social norms, freely breaking into song and quickly gaining popularity among her peers.

Fauna is Howie's other twin daughter. Like her sister, she is homeschooled, avoids popular culture per her father's rules, and enjoys singing enthusiastically in public settings without shame.

Real name Farley Drexel Hatcher, Mini is Howie's three-year-old son. He acts wildly and mimics Fudge's behavior, which severely aggravates Fudge, who hates sharing his distinctive name with the younger boy.

Uncle Feather is Fudge's beloved pet myna bird. He typically mimics French phrases, but his sudden, unexplained silence causes deep distress for the family and initiates a chaotic search for a cure.

Rich is Fudge's new classmate and quick best friend. Coming from a wealthy background, he frequently brags about his family's money, beach house, and cooks, exacerbating Fudge's existing financial obsession.

Mrs. Osterman is an elderly resident of the Hatchers' apartment building. She is a former Broadway performer who shares glamorous stories of New York and occasionally finds herself caught up in the children's mishaps.

Sheila is a family friend and neighbor who frequently interacts with the Hatchers. She holds strong opinions about Fudge's behavior but happily befriends the visiting Hawaii cousins.

Melissa is the Hatchers' new neighbor. She attends the same school as Fudge in the "mixed-up group" and brings her cat along during the building's trick-or-treating festivities.

Beverly is Mr. Fargo's new girlfriend. Her presence and potential marriage to Mr. Fargo cause Jimmy to worry about his changing family dynamic.

Henry is the elevator operator in the Hatchers' building. He teaches the children the rules of the new self-service elevator and keeps a watchful eye on the residents' safety.

Turtle is Peter's pet dog. He is a friendly, calm companion whose pawprints are even used in Fudge's homemade art projects.