Inti is a biologist leading a controversial project to rewild wolves in Scotland. She has mirror-touch synesthesia, a neurological condition that causes her to physically feel the sensations of living creatures around her. She acts as the primary caretaker for her twin sister, Aggie, and struggles to balance her intense empathy with her desire to protect herself from the cruelty of others.

Aggie is Inti's identical twin sister and a former language teacher. Currently suffering from severe PTSD, she lives secluded in Inti's cottage and communicates minimally, mostly relying on a private sign language she shares with Inti. Before her trauma, she possessed an outgoing, spontaneous personality that balanced her sister's intensity.

Duncan is the police chief of the rural Scottish community where Inti's team operates. A rugged man with a distinct limp from a childhood injury, he acts as a peacemaker between the angry locals and the biologists. He balances his duty to the town with a growing personal interest in Inti.

Alexander is Inti and Aggie's Canadian father. A former logger turned passionate naturalist, he lives a subsistence lifestyle in the British Columbia wilderness. He teaches his daughters to hunt, track, and revere the natural world, though his deteriorating mental health eventually strains their relationship.

Inti and Aggie's mother works as a detective in Sydney, Australia. Pragmatic and hardened by her job, she focuses on the harsh realities of human nature. She actively warns her daughters about the dangers of extreme empathy, attempting to armor them against people who might exploit their kindness.

Stuart owns Burns Farm and holds significant influence in the local agricultural community. He possesses a volatile temper that causes most townspeople to avoid provoking him. His aggressive behavior toward his wife, Lainey, and his open hostility toward the wolf project quickly draw Inti's ire.

Red is a prominent farmer who serves as the loudest voice opposing the wolf reintroduction. He views the predators as a direct threat to the agricultural lifestyle and vows to protect the local livestock by any means necessary. His interactions with Inti are characterized by deep ideological opposition.

Lainey is Stuart's wife, a woman who breaks horses for a living. She frequently sports bruises and injuries that she dismisses as occupational hazards. She maintains a facade of normalcy to avoid triggering her husband's anger, despite Inti's direct attempts to intervene.

Gus is a medical student studying to be a neurosurgeon who becomes involved with Aggie in Australia. He is arrogant, dismissive of Inti's synesthesia, and prefers loud parties and heavy drinking. He insists that sensations reside purely in the mind, fundamentally clashing with Inti's physical empathy.

Number Six, secretly nicknamed "Ash" by the biologists, is a female wolf released into the Abernathy pack. She forms a bond with Number Nine and becomes pregnant shortly after her release. Inti watches her progress closely, seeing the wolf's survival as a vital marker of the project's success.

Number Ten is a fiercely independent female wolf from the Glenshee pack. Unlike the others who hesitate, she bolts into the wild the moment her cage opens. She displays unusual aggression and a lack of fear toward humans, making her a target of concern for both the farmers and the biologists.

Evan is a Scottish colleague working alongside Inti on the rewilding project. He handles the public relations aspect of the conservation effort, attempting to educate the angry locals about apex predators and ecosystem balance.

Gealaich, known as Gall, is a horse purchased by Inti from Stuart Burns at an exorbitant price. Initially lame and facing execution, the horse is brought to Inti's cottage paddock to live peacefully.

Bonnie is a local policewoman in the Highland town who works under Duncan MacTavish. She handles official questioning regarding community disturbances and missing persons.

Colm is a local Scottish resident who is deeply opposed to the wolf project. He takes matters into his own hands when livestock are killed, representing the direct threat the townspeople pose to the predators.

Mrs. Doyle works at the local pharmacy and represents a different faction of the town. Unlike the vocal farmers, she supports the conservation efforts and understands the importance of rewilding the Highlands.

Number Nine is a male wolf who successfully forms a mating pair with Number Six in the wild. His survival is a key focus for Inti as the wolves attempt to establish a pack near the farmlands.

Fingal is Duncan MacTavish's loyal dog, a constant companion to the police chief as he patrols the Scottish community.

Fergus is a local man and a longtime friend of Duncan MacTavish. He provides Inti with background information regarding Duncan's past.

James is Gus's cousin. He frequently attends Gus's rowdy parties and enables his volatile behavior.