The Greek god of the sun, poetry, and healing, currently bound to the mortal form of an awkward sixteen-year-old boy named Lester Papadopoulos. Stripped of his divine powers by his father Zeus, he is on a final quest to Manhattan to stop the resurrected emperor Nero and his ancient nemesis, Python. Along his journey, he struggles with the limits of mortality while developing a deeper sense of empathy and humility.

A thirteen-year-old demigod daughter of Demeter and Apollo's loyal companion. Raising plants with her botanical magic and fighting with twin swords, she is resilient and fiercely protective of her friends. She faces the emotional trauma of being raised as a child weapon by her abusive adoptive father, Nero, as she prepares to confront him in his tower.

A resurrected, cruel Roman emperor and the leader of the Triumvirate. Operating out of a sleek corporate tower in Manhattan, he seeks to dominate the world and hoards volatile Greek fire beneath the city. He is a manipulative abuser who leverages emotional terror, particularly against his adoptive daughter Meg, to maintain absolute control.

A colossal, primordial serpent and Apollo's legendary arch-nemesis. Having seized the Oracle of Delphi, he controls prophecies and pulls the strings behind Nero's ambitions. He represents an ancient, adaptable evil seeking to choke the life out of the world and destroy Apollo completely.

A tall, muscular Gaul warrior with an elaborate mohawk who works in Nero's forces. Also known as Lu, she trained Meg as a gladiator during Meg's time in the Imperial household. Despite her fearsome reputation and employment under Nero, she secretly harbors a deep loyalty to Meg and devises a dangerous infiltration plan.

The demigod son of Hades who possesses the ability to shadow-travel and communicate with the dead. Quiet, intense, and deeply grieving the recent loss of his friend Jason Grace, he steps up to lead Apollo and Meg through dangerous subterranean routes to bypass Nero's security.

A mortal heiress who serves as the Pythia, or priestess of the Oracle of Delphi. Though Python's hold on Delphi restricts her visions, she remains a crucial source of guidance, using her prophetic gifts and knowledge of New York real estate to help Apollo navigate the dangers of Nero's tower.

The demigod son of Apollo and head healer at Camp Half-Blood. He eagerly joins the perilous journey to New York to support his father's final trials and watch over his boyfriend, Nico.

Percy Jackson's mother. She offers a warm, safe haven and fresh supplies to Apollo and Meg when they first arrive in New York, embodying the unconditional parental love that Apollo deeply admires.

Percy Jackson's mortal stepfather and Sally's husband. He helps welcome Apollo's group into his home, serving as a rare example of a supportive, loving father figure.

The king of the Olympian gods and Apollo's father. Arrogant and uncompromising, he is responsible for casting Apollo down to Earth in mortal form as a punishment for past failures.

The Greek god of wine, serving as the camp director of Camp Half-Blood. Like Apollo, he is enduring a mortal punishment from Zeus, though he uses his position to sarcastically taunt his brother rather than offer sympathy.

A sentient, magical artifact from the Grove of Dodona. Speaking in an exasperating Shakespearean dialect, it acts as a reluctant but vital prophetic guide to Apollo during his trials.

The leader of the troglodytes (trogs), a subterranean humanoid people. Named by Apollo due to his appearance, he negotiates with the heroes to help sabotage Nero's underground stores of Greek fire.

One of Nero's adopted demigod children. Though terrified of his stepfather, he is forced by Nero to carry out violent punishments against the emperor's enemies, illustrating the depth of Nero's abusive control over children.

The goddess of the hunt and Apollo's immortal twin sister. She watches over her brother's trials from Olympus with concern and serves as a comforting presence.