Tomás is a 19th-century cartographer working for the British Ordnance Survey. A survivor of the Great Famine, he initially suppresses his childhood trauma by focusing on the precise, empirical work of mapping. Following a transformative encounter at a hidden holy well, he alters his life's course, deciding to reject colonial charts in favor of documenting the terrain based on indigenous memory and lore.

Liam is Tomás and Seraphina's ten-year-old son, who serves as a chainboy on his father's surveying missions. Frightened by both the eerie local terrain and his father's sudden erratic behavior, he desperately seeks stability. He finds comfort in the rigid structure of the Catholic Church, eventually falling under the influence of the local priest who offers him an alternative path.

Enda is the fiercely independent eldest daughter of the family. Chafing against the gender expectations of her era, she resents being excluded from her father's work and formal schooling. She discovers a profound talent for the fiddle, using traditional music to forge her own identity and maintain a deep connection to her cultural heritage.

Rose is the second daughter, naturally assuming a domestic and caregiving role within the family. While her siblings seek escape through intellectual or artistic pursuits, she remains focused on maintaining the household and caring for her younger brother. She forms a deep attachment to the family's large wolfhound, seeking security in a precarious environment.

Eugene is the youngest child, a non-verbal boy who perceives the world through a deeply intuitive connection to nature. Rather than relying on language, he communicates directly with the physical environment around him. His innate attunement to the earth leads him to discover ancient artifacts buried in the local bog.

Seraphina is Tomás's wife and a practical, grounding presence for her family. Having survived the workhouses during the Great Famine, she balances her husband's volatile nature with a strict demand for economic security. Often called Phina, she manages the household's meager resources while demonstrating deep emotional intuition regarding her children's needs.

The Widow is a resilient local woman who lost her entire family during the Great Famine. She acts as a vital source of historical memory for the depopulated peninsula. Taking in Tomás's family during moments of crisis, she provides them with practical support, shelter, and guidance in navigating the harsh realities of their world.

Father Joseph is a local Catholic priest who views indigenous spiritual practices as dangerous heresy. He subjects Tomás to a brutal, multi-day exorcism after the cartographer's awakening at the holy well. Seeking to undermine Tomás's influence over his own household, he actively mentors Liam to draw the boy toward the priesthood.

Brith is a young girl from an ancient, pre-Christian tribe whose story is preserved in the soil of the peninsula. Sacrificed near the holy well to appease the gods, her perfectly preserved remains are discovered millennia later. She represents the deep, cyclical history of the terrain.

Bran is a massive, friendly gray wolfhound who adopts the family after encountering the children on the peninsula. He serves as a fiercely loyal guardian, particularly to Rose. His presence echoes the ancient hounds that once protected the region's early inhabitants.

Anatole is an accordion player and immigrant from the Baltic region traveling with his sister. He connects with Enda over their shared love of traditional music. Their interactions provide a sense of community for displaced travelers seeking a new life away from their homelands.

The Viscount's Son is a young local aristocrat who embodies the entitlement and casual cruelty of the Anglo-Irish landowning class. His violent actions pose a persistent threat to the local tenant farmers and directly impact Rose's physical safety.