Dory is an energetic six-year-old girl who spends her summer vacation running around her house in a nightgown. Known as "Rascal" by her family, she struggles to regulate her emotions and frequently throws temper tantrums when frustrated or ignored. She constructs elaborate pretend games, spots monsters in broken drawers, and interacts with imaginary friends to cope with feeling isolated from her older siblings.

Luke is the middle child of the family and frequently aligns himself with his older sister. He happily participates in the games Violet designs, such as letting her paint his toenails, and echoes her dismissive attitude toward their youngest sister to maintain his preferred status. Despite his initial aloofness, he harbors a softer side and a specific interest in dogs.

Violet is the oldest sibling in the household and the primary architect of the children's social hierarchy. She prefers structured games like playing "house" that reinforce traditional roles, rather than the chaotic fantasies her youngest sister enjoys. She frequently berates Dory for being noisy and messy, using her age to assert authority over both her siblings.

Mrs. Gobble Gracker is a fictional 507-year-old child-stealing robber invented by Violet and Luke. In Dory's active imagination, she manifests as a physical threat with black, needle-like teeth and pockets full of dirty tissues. She acts as a tangible target for Dory's frustrations and a tool Dory uses to process the frightening aspects of the adult world.

Dory's mother and father are the primary authority figures who manage the practical logistics of the household. They operate outside the logic of childhood fantasy, focusing on getting Dory dressed, taking her to medical appointments, and enforcing basic discipline. They view Dory's public outbursts and wild imagination as embarrassing disruptions to daily life.

Mary is Dory's primary imaginary friend, manifesting as a horned, striped monster roughly the same size as a six-year-old. She remains constantly available for playtime, offering Dory companionship when the older siblings refuse to engage. She acts as a docile sidekick who readily absorbs Dory's anxieties and hides under beds during scary moments.

Mr. Nuggy is a magical imaginary companion who identifies as a fairy godmother despite his gnome-like appearance. He materializes when Dory feels particularly low or questions her own maturity. He assists Dory by pretending to turn her into a pineapple or a puppy when she asks for help.

Baby Cherry is Violet's favored baby doll and a frequent prop in the older siblings' games. Though an inanimate object, the doll occupies the social role that Dory desperately wants to fill. The toy receives the gentle care, inclusion, and attention from Violet that Dory feels she deserves.

The doctor is a medical professional tasked with giving Dory a checkup and a shot. Unlike Dory's parents, the doctor attempts to negotiate with Dory on her own terms, humoring Dory's barking during an eye exam.