Agba is a young Moroccan stableboy with a speech disability who serves in the royal stables. Wearing a turban and a hooded mantle, he approaches his difficult circumstances with a tireless work ethic and quiet, patient endurance. He forms a profound bond with the horse Sham, dedicating his energy to nurturing the animal despite facing severe displacement, neglect, and poverty. His lack of speech often leaves him vulnerable to misunderstandings with human authorities, solidifying his preference for the company of animals.

Sham is a golden bay Arabian horse born in the royal stables of Morocco. He bears two distinct markings: a white spot on his hind heel signifying incredible speed, and a wheat ear pattern on his chest denoting misfortune. Spirited, joyful, and deeply inquisitive, he refuses to let anyone but Agba hold his reins or guide him. His unyielding will and fierce loyalty often put him at odds with European handlers who demand simple obedience rather than independence.

The Wood Carter is an enormously built, physically imposing man in Paris who stalks the streets like a tiger and constantly wields a horsewhip. Driven by greed and an utter lack of sympathy, he overburdens his animals in freezing weather simply to increase his profit margins. He casually exploits Agba, forcing the boy to perform heavy labor in exchange for nothing more than space in an unheated shed.

The Earl of Godolphin is an ambitious English nobleman and wealthy philanthropist who aspires to breed the finest horses at his estate, Gog Magog. He frequently engages in charitable endeavors, demonstrating a willingness to use his resources to assist the less fortunate. Though he possesses generous instincts toward Agba, his aristocratic pride and strict expectations occasionally blind him to Sham's true worth. He relies heavily on established pedigrees and the advice of his trainers when evaluating his stock.

Signor Achmet is the gruff Chief of Grooms in the royal stables of Morocco. He manages the stableboys and horses with strict discipline, constantly answering to the volatile Sultan. He harbors a strong superstitious fear regarding equine omens, immediately identifying the unlucky wheat ear mark on Sham's chest.

Mulai Ismael is the fierce and bloodthirsty Sultan of Morocco who wields absolute power over his subjects. He utilizes his horses as tokens of diplomacy, viewing them as tools for political leverage to impress the French court rather than living beings. He displays little patience for those who fail to answer his questions immediately, punishing hesitation with threats of violence.

Louis XV is the young, impressionable boy King of France, who is monarch in name only. Because he relies heavily on his grand-uncle and other advisers, he lacks the authority to properly appreciate the Arabian horses gifted to him. He treats the presentation of the animals as an amusement rather than a diplomatic exchange.

Monsieur le Duc is a haughty, vain adviser to King Louis XV. Operating with extreme cultural prejudice, he mocks the Sultan's diplomatic gift and dismisses the Arabian horses as inferior sand sifters. His arrogance directly leads to the regal horses being relegated to common manual labor in Paris.

Grimalkin is a resilient tomcat who survives on the margins of society, initially living in the Parisian wood carter's shed. He forms an immediate, comforting friendship with Agba and Sham, sharing their meals and sleeping spaces. He provides the pair with physical warmth and silent support through their most difficult and displaced times.

Jethro Coke is a widowed English Quaker and retired merchant living on the outskirts of London. He steps forward to purchase Sham after witnessing the horse's collapse in the icy streets of Paris. Although well-intentioned and instrumental in moving Sham to England, his practical approach to horses eventually causes him to prioritize his family's safety over Agba's stability.

Mistress Cockburn is the plump, nurturing housekeeper managing the household for Jethro Coke. With dark, raisin-like eyes and a warm demeanor, she provides Agba with restorative cooking and teaches him how to read English. She serves as a rare source of maternal warmth and dedicated advocacy in a world largely indifferent to the stableboy's struggles.

Benjamin Biggle is Jethro Coke's inexperienced son-in-law who resides at the merchant's estate. His complete lack of horsemanship causes him to mishandle Sham during a riding lesson, leading to a violent reaction from the horse. His subsequent fear dictates the household's decision to send the animal away.

Roger Williams is the proprietor of the Red Lion Inn in London, who temporarily houses Sham and Agba. He treats the boy relatively kindly compared to other adults and attempts to defend him against false accusations. However, his efforts to maintain peace at his inn are frequently overridden by his hostile wife.

Mrs. Williams is the cold and unyielding wife of the innkeeper. She harbors a deep disdain for Agba's silent presence, reacting to his loyalty with intense suspicion. Her hostility culminates in false accusations of theft, demonstrating her eagerness to criminalize a vulnerable outsider.

Silas Slade is a weasel-eyed man reputed to be the best horse-breaker in London. He utilizes cruel, restrictive methods in an attempt to crush the spirit of defiant horses. He views an animal's independence as a personal affront that must be beaten out of them.

Constable Muggins is a local London law enforcement officer who readily accepts Mrs. Williams's accusations against Agba. He lacks any sympathy for the boy's situation and brutally threatens the child's animal companions when they attempt to defend him. He physically chains Agba, treating the nonverbal youth as a dangerous criminal.

The Dowager Duchess of Marlborough is an aristocratic philanthropist who frequently travels to Newgate Jail to offer assistance to the incarcerated. Her chance encounter with Mistress Cockburn in the street sets off a chain of events that directly alters Agba's dire circumstances. She leverages her immense social standing to right a local injustice.

Titus Twickerham is the meticulous breeder and head trainer at the Gog Magog stables. Deeply devoted to the established hierarchy of the English stables, he takes an instant dislike to the small Arabian horse. He acts as a vocal critic of Sham's potential, preferring the massive, traditional English stallions.

Hobgoblin is an enormous, highly esteemed stallion referred to as the king of Gog Magog. Boasting an exalted pedigree and a massive frame, he is expected to sire the Earl of Godolphin's finest stock. He stands in sharp contrast to the slighter, swifter Sham, representing the traditional European ideal of a powerful draft and breeding horse.

Lady Roxana is a beautiful white mare acquired by the Earl of Godolphin for his ambitious breeding program. She proves to have her own preferences upon arriving at the estate. She shows immediate interest in the spirited Sham, joyfully rejecting the hulking stallion originally chosen for her.

Samuel Riddle is the proud 20th-century owner of the American champion racehorse Man o' War. He values his horse's health and dignity over the pursuit of endless trophies, opting to retire the animal rather than risk physical injury under heavy racing weights. He demonstrates a protective loyalty that honors the horse's historical lineage.

Man o' War is a legendary red-gold stallion renowned for his astonishing speed and immense fighting heart on the North American racing circuit. He acts as a modern representation of long-standing equine excellence. His carefully managed career connects the present day back to the endurance of his famous ancestors.