Drew is a sensitive, anxious 12-year-old boy from Chicago who prefers reading indoors to outdoor activities. He struggles with his parents' expectations that he act more stereotypically tough and outdoorsy. When he travels back to 1910, he must adapt to a new set of societal rules while discovering his own inner courage.

Andrew is Drew's relative from the year 1910, initially encountered as a boy dying of diphtheria. Before his illness, he was known as a confident, mischievous, and occasionally rough boy who adheres to his era's aggressive standards of behavior. Beneath his boasting exterior, he possesses a deep love for his family and a hidden emotional vulnerability.

Hannah is Andrew's older sister in 1910. She is a warm, free-spirited girl with sparkling eyes who resists the era's strict expectations for ladylike behavior. She enjoys climbing trees, taking off her shoes, and playing marbles, providing Drew with vital friendship and lessons in self-reliance.

Edward is Andrew's conniving and unpleasant cousin in 1910. He is a persistent bully who issues dangerous challenges and runs to his parents with lies to avoid facing consequences. His animosity stems from a larger family feud over property inheritance.

Theo is Andrew and Hannah's rambunctious younger brother. He deeply admires his older brother and expects him to display physical courage, mischief, and a willingness to brawl. His expectations for traditional toughness create a challenging standard for Drew to meet while posing as Andrew.

Aunt Blythe is Drew's energetic great-aunt who enjoys the challenging project of restoring the derelict family home. She is progressive, empathetic, and takes Drew's fears seriously. She provides a welcoming presence in the otherwise spooky house.

Papa is Andrew's stoic, authoritative father. While he possesses an underlying warmth, he strictly enforces the era's standards for gentlemanly behavior. He relies on harsh corporal punishment with a belt to discipline his children, reflecting the historical norms of his time.

Mama is Andrew's warm and kind mother. She is highly protective of her children's health, often attempting to shield the boys from overexertion. She defends them against her husband's strict punishments, asking for leniency.

Great-Grandfather, often called "Father," is Drew's cantankerous elderly relative who lives with Aunt Blythe. He is wheelchair-bound and deeply hostile toward Drew, treating the boy with immediate disdain after confusing him with a hated figure from his past.

Martin is a cruel bully from Drew's life in Chicago. The fear of facing Martin's public shaming and name-calling is strong enough that Drew prefers spending the summer in a spooky, isolated house rather than attending camp.

Drew's father is an archaeologist who encourages a traditional, stoic form of behavior in his son. He dismisses Drew's anxiety and sensitivity, advising him not to cry and hoping a summer away will make him more outdoorsy.

Drew's mother travels with her husband on archaeological digs. She agrees with leaving Drew at the ancestral home for the summer, hoping the experience will help him become less fearful and more adventurous.

John Larkin is a young man in 1910 who takes an interest in Hannah. He is patient, owns a motorcar, and is unfazed by Hannah's tomboyish behavior. He even offers to teach boxing tricks to the boys to help them defend themselves.

Mrs. Armiger is a strict music teacher in 1910. She is familiar with Andrew's past mischievous behavior, including an incident involving glue and a metronome. She is shocked by the polite demeanor displayed by the boy she believes is Andrew.

Buster is the Tylers' large, energetic family dog in 1910. He possesses a keen sense of smell and immediately senses that Drew is not actually Andrew, barking menacingly at the perceived imposter.

Binky is Aunt Blythe's small family dog in the present day. The dog provides comfort to the anxious Drew, who frequently clings to the animal when frightened by the spooky noises in the ancestral home.