Conor is a 13-year-old English boy struggling to maintain household responsibilities while his mother undergoes medical treatments. He deals with intense social isolation at school and hides a dark, recurring nightmare he refuses to share with anyone. Fiercely independent, he repeatedly pushes away offers of help from adults and peers alike.

She is a young, divorced mother battling a serious, unnamed illness that leaves her physically exhausted and often sick. Despite her declining health, she maintains a cheerful facade and tries to shield her son from the grim realities of her condition. She relies heavily on her mother and son to keep the household running.

The Monster is an ancient, wild entity that appears as a towering figure formed from the branches and leaves of a yew tree. Claiming to be a creature of healing and destruction, it visits Conor to tell him three morally ambiguous stories. It demands that Conor eventually tell a fourth story containing his deepest truth.

Grandma is a practical, career-focused woman who wears tailored pantsuits and keeps her house like an immaculate museum. She takes a blunt, realistic approach to her daughter's illness, often clashing with Conor's denial. Despite their rocky dynamic, she works tirelessly to ensure Conor and his mother are cared for.

Conor's father lives in America with a new wife and baby, speaking with a noticeable American accent that makes him feel like a stranger to his son. He flies to England at his ex-wife's request but hesitates to disrupt his new life to offer Conor a permanent home. He attempts to bond with Conor during short visits but struggles to connect.

Harry is the school bully who singles Conor out for psychological and physical torment. Unlike typical bullies, Harry is highly observant and recognizes Conor's internal desire for punishment. He operates with an unsettling calmness and controls his cronies to ensure he is the only one who physically targets Conor.

Lily is a childhood friend of Conor whose mothers were close friends. Their relationship fractures after Lily reveals the truth about Conor's mother's illness to their classmates. Despite Conor's fierce resentment and rejection, she continues trying to support and defend him at school.

Miss Kwan is the Head of Year teacher at Conor's school. She is aware of Conor's difficult home situation and attempts to offer him leniency and a safe space to talk. Her well-intentioned pity inadvertently makes Conor feel more singled out and isolated.

Anton is one of Harry's cronies at school. He participates in intimidating Conor but strictly follows Harry's rule that only Harry is allowed to physically touch him.

Sully is another of Harry's followers. His insensitive remarks about the physical effects of Conor's mother's medical treatments prompt Lily to shove him, sparking a conflict in the schoolyard.

A character in the Monster's first story, she is the young, beautiful second wife of an old king. Suspected of poisoning the king to seize power, she rules as queen regent and attempts to force the young prince into marriage to secure her throne.

The young royal heir in the Monster's first tale. He falls in love with a farmer's daughter and flees the kingdom to escape his step-grandmother's marriage plot. His actions spark a major conflict within the kingdom.

A commoner in the ancient kingdom who captures the prince's heart. She runs away with him to seek a new life, sleeping beneath the shade of a yew tree where a sudden tragedy strikes.

An ancient healer from the second tale who relies on herbs, barks, and leaves. Bitter and demanding, he charges high prices for his cures and frequently clashes with the local parson over access to a healing yew tree.

A religious man in the second tale who publicly denounces the Apothecary's traditional medical practices. When his daughters fall gravely ill, he is forced to abandon his stated principles in a desperate bid to save them.

The lead administrator at Conor's school. She handles the fallout of a severe altercation involving Conor and Harry, deciding to offer leniency due to Conor's difficult personal circumstances rather than issuing a standard expulsion.