Jeremy is a creative, sensitive sixth-grade boy and the son of a local veterinarian. He loves art and drawing but suffers constant criticism from his school's art teacher. Socially isolated by school bullies and academic pressure, his life shifts entirely when he stumbles into a mysterious magic shop and purchases a strange, multicolored sphere that requires his care.

Tiamat is a young dragon with red scales and emerald-green eyes who hatches from an egg purchased at a magic shop. She communicates through mental images rather than spoken words and remains invisible to most humans. Curious and rapidly growing, she possesses a mischievous streak but is highly sensitive to the emotions of her caretaker.

Mary Lou is a classmate who openly harbors a crush on Jeremy, initially leaving him notes on purple paper. Her father serves on the local school board, which complicates social dynamics at school. She shares a deep interest in reading, fantasy, and animals, making her more observant than other students in Jeremy's circle.

Mr. Kravitz is a strict, critical art teacher at Jeremy's school. He favors precision and realism over imagination, actively forbidding fantasy art in his classroom. He frequently uses public humiliation as a disciplinary tactic, causing heavy tension with his creatively inclined students.

Miss Hyacinth Priest is the children's librarian at the local library, recognized by her long hair and dangling earrings. She provides unusual and specific reading material to patrons seeking specialized information. She offers quiet support and maintains a knowing attitude regarding magical subjects.

Specimen is a sixth-grade student with thick glasses, long fingers, and a clear talent for art. He eagerly anticipates the spring art contest, hoping to win the grand prize of painting the department store window. His practical nature limits his interest in fantasy or libraries, which eventually strains his friendships.

Mr. S. H. Elives is the stern, old proprietor of Elives's Magic Supplies, a mysterious shop filled with strange items. He has walnut-colored skin and long white hair. He sells a unique sphere to Jeremy with strict, specific instructions on its care and authorial knowledge of magical subjects.

Dr. Thatcher is Jeremy's father and a practicing veterinarian in Blodgett's Crossing. He often has his son assist with the animal patients at his clinic. He maintains a calm and easily amused demeanor, finding humor even during chaotic household events.

Mrs. Thatcher is Jeremy's mother, who manages the household and expects her son to contribute to chores. She places high importance on hosting successful dinner gatherings to support her husband's veterinary practice.

Mr. Martinez is the principal at Jeremy's school. He takes a gentle, understanding approach to student struggles, offering an open door and guidance when problems arise.

Howard Morton is a local student who torments others with taunts and rumors. He frequently targets classmates with mocking noises and playground intimidation.

Freddy is a local bully who engages in cruel behavior toward both students and animals. His malicious actions often force other children to intervene or flee to protect themselves.

Grief is the Thatcher family's large, enthusiastic dog. He drools frequently and is easily frightened by unusual occurrences in the household, resulting in occasional domestic chaos.

Fat Pete is a cat associated with the veterinary clinic who often crosses paths with the neighborhood children. He occasionally finds himself at the mercy of local troublemakers.

Uwila is an owl belonging to Mr. Elives. The bird often sits perfectly still in the shop, leading visitors to mistake it for a stuffed animal.