Aubry is a French woman originally from Paris who suffers from an unexplainable condition that causes immense physical pain if she remains in one place for more than a few days. Forced to leave her home at age nine, she spends her life traveling across the globe to outrun her affliction. She develops survival skills like hunting and fishing out of necessity. Though initially a stubborn child, her constant movement forces her to adapt and connect with strangers.

Marta is a determined Mexican journalist who tracks Aubry across the globe to write her life story. She travels disguised as a man to avoid harassment during her long journeys. She maintains extensive binders of newspaper clippings and notes about Aubry's movements.

Uzair is an amateur scientist and wealthy collector living in Tripoli. He gathers artifacts, rare rocks, and fossils in a personal effort to understand the natural world. He firmly believes in the power of scientific reasoning and becomes obsessed with curing Aubry's affliction using herbal remedies and logic.

The Prince rules an unnamed region in India under British colonial authority. He pays British taxes out of his own pocket to protect his impoverished citizens. He shows compassion to Aubry, offering her shelter in his palace and protecting her from legal trouble.

Vincente is an older man from Patagonia who operates a hidden refuge in the Amazon rainforest. After leaving his wife, he walked across South America and discovered that lost and orphaned children naturally followed him. He calmly cares for dozens of youths, tending a garden and treating their injuries without asking questions about the impossible.

Qalima is a mysterious artist who paints elaborate, colorful visions. Her family fled their home during a war, and she now uses her prophetic artwork to assist the Prince whenever he needs guidance. She maintains a quiet, observant presence in the palace.

Lionel is a Black accountant who attended Oxford and works in Russia. He speaks French with an accent and treats Aubry with respect and gentleness. Unlike others who try to control or cure her, he views her forced movement as a reward rather than a punishment.

Pathik is a nomadic hunter living in the Himalayas with his extended family. He communicates with Aubry entirely through gestures and shared actions since they do not speak the same language. He relies on the harsh environment for survival and hunts mythic creatures to feed his people.

Emily is a vacationing mother from New Zealand traveling through Southeast Asia. She immediately recognizes Aubry from international newspaper articles and eagerly listens to the stories of her travels.

Vaughan is a father traveling with his family on a ferry in Siam. He is highly cautious and demands scientific or medical explanations for unknown situations, initially fearing that Aubry carries a contagious disease.

Sylvie is Aubry's sister who grows up in Paris. She initially resents Aubry for acting selfishly at the wishing well, believing Aubry's actions caused a tragedy in their neighborhood.

Pauline is Aubry's sister. She later studies medicine specifically to find a cure for Aubry's mysterious affliction.

Private Hayley is a British soldier stationed in India enforcing colonial rule. He actively searches for the person responsible for killing three men in a nearby ravine.

Hamza is a servant working in Uzair's household in Tripoli. He observes Uzair's harsh treatment of Aubry and ultimately acts on his own conscience to help her.

Ollie is a young boy living in Vincente's Amazon refuge. He bonds with Aubry over daily chores and finds comfort in her presence at the camp.

Kuliki is a four-year-old girl who arrives at the jungle camp after her house is destroyed in a storm. She follows fireflies to safely locate the refuge.