Firedrake is a brave silver dragon who lives in a hidden valley community. When humans threaten to flood their home, he volunteers to search for the Rim of Heaven, the mythic ancestral home of the dragons. He survives purely on moonlight, which powers his ability to fly, and breathes blue fire that can heal or reveal enchantments. He is highly trusting and friendly, quickly accepting humans and other creatures as companions on his long journey.

Sorrel is a spotted sulfur-yellow forest brownie from the Scottish Highlands. She is naturally grumpy, deeply suspicious of humans, and uses various mushroom names as exclamations and insults. Despite her strong preference for staying safely in her cave, she accompanies Firedrake on his dangerous quest strictly out of loyalty to her best friend.

Ben is a young orphan living alone in an abandoned warehouse. He is adventurous, empathetic, and entirely unfazed by the sudden appearance of magical creatures in his city. Lacking any family ties, he jumps at the chance to join Firedrake and Sorrel on their journey to the Himalayas, proving to be a brave and compassionate companion.

Nettlebrand, often called the Golden One, is a massive, artificially created monster covered in indestructible golden armor. Designed centuries ago by an alchemist specifically to hunt silver dragons, he possesses an inherent drive for destruction. Though he cannot fly, he commands a flock of raven spies and travels rapidly through bodies of water, waiting for the chance to resume his hunt.

Twigleg is a spindly, red-haired homunculus—an artificial being created by alchemy. He serves as Nettlebrand's armor-polisher and spy, following the golden dragon's orders out of sheer terror of being eaten like his brothers. After stowing away with Firedrake's group, he experiences genuine kindness from Ben, causing a severe internal struggle over his loyalties.

Professor Greenbloom is an eccentric archeologist and historian who specializes in studying fantastical creatures. He encounters the travelers during a dig in Egypt and quickly becomes an invaluable ally. He offers Ben and the magical creatures vital information, specialized supplies, and steadfast friendship as they journey eastward.

Gravelbeard is a mountain dwarf who encounters Firedrake's group early in their journey. Driven entirely by his love for treasure and precious stones, he acts as a willing informant for Nettlebrand. He tracks the silver dragon and takes over armor-polishing duties in hopes of being rewarded with one of Nettlebrand's indestructible golden scales.

Rosa is an observant rat who brings the urgent warning to the silver dragons that humans are coming to flood their valley. She provides Firedrake with crucial initial advice, directing him to seek out her mapmaker cousin in the human city.

Gilbert is a white rat living in a hidden study inside a human warehouse in the city. He operates as a mapmaker, compiling geographical information from various animal travelers, and provides Firedrake's group with the route to the Himalayas.

Lola is an ace rat pilot who navigates the skies in a heavily modified toy airplane. She surveys the Himalayas for her uncle Gilbert and encounters Firedrake's group in the mountains, offering her keen navigational skills to assist them in their search.

Vita is the wife of Professor Greenbloom and a dedicated scholar of fantastical creatures in her own right. She specializes in studying brownies and shares her family's deep fascination with the magical world, supporting her husband's efforts to help Firedrake.

Guinevere is the young daughter of Professor Barnabas and Vita Greenbloom. Roughly Ben's age, she shares her family's extensive knowledge of fantastical creatures and eagerly welcomes the travelers into her life.

Zubeida is a highly knowledgeable dracologist and colleague of Professor Greenbloom. Living in a village near the Indus River, she serves as a vital guide for the travelers, sharing local legends about dragons and offering tools to aid Firedrake's flight.

Burr-Burr-Chan is a four-armed Dubidai brownie who once lived alongside the silver dragons in the Rim of Heaven. He possesses deep historical knowledge of the hidden mountain paths and agrees to lead Firedrake's group on the final leg of their journey.

Maia is a female silver dragon who resides in the Himalayas. Unlike many of her peers, she remains active and vigilant, representing a crucial link to the dragons' ancestral past and offering immediate help to Firedrake.

Slatebeard is the oldest dragon in the Scottish Highlands community. He retains faint memories of being born in the Rim of Heaven and encourages Firedrake to undertake the journey eastward to find it.