Nena is the hardworking and headstrong daughter of the patrón of Rancho Los Ojuelos. Expected by her family to marry for an alliance, she pushes back by training as a curandero (healer) to prove her worth. She shares a deep emotional bond with her childhood friend Néstor and feels an intense kinship with her family's land.

Néstor is a skilled vaquero who fled Los Ojuelos after a tragic incident involving Nena when they were thirteen. Having lost his first home to invading white settlers and his second home at the rancho, he wanders northern Mexico taking temporary work. He uses charm and alcohol to mask his persistent guilt while striving to save money for his own land.

Beto is a talkative, charming storyteller and an experienced vaquero who took Néstor under his wing six years ago. Born to a white father and a Mexican mother, he frequently faces suspicion but remains fiercely loyal to his fellow vaqueros. He possesses high emotional intelligence and frequently bridges the communication gaps between Néstor and Nena.

Don Feliciano is the powerful patrón of Rancho Los Ojuelos. He enforces strict social hierarchies on the rancho and prioritizes his family's security over the desires of his workers. Driven by a desire to protect his land from encroaching threats, he views his daughter's marriage as a strategic tool for building alliances with other wealthy landowners.

Doña Mercedes is Don Feliciano's wife and the matriarch of the Serrano family. She cares deeply about societal perception and the family's honor. She actively polices Nena's behavior and enforces strict rules about her interactions with men of lower social standing.

Félix is Nena's older brother and the responsible heir to Don Feliciano. Calm, composed, and driven by duty to his family, he holds the respect of his parents and community. He frequently uses his privileged position to speak on Nena's behalf when their parents refuse to listen to her directly.

Abuela is Néstor's grandmother and the respected lead curandero of Los Ojuelos. Though her health is deteriorating in her old age, she holds immense knowledge of traditional medicine, aura work, and local folklore. She trains Nena in healing arts and offers emotional wisdom to her family.

Bernabé is Néstor's uncle who took his nephew in and fled to Los Ojuelos after their previous rancho was violently taken over by Anglos. He works hard as a vaquero and attempts to keep his family safe under the patronage of the Serrano family.

Casimiro is Néstor's cousin and a vaquero at Los Ojuelos. Polite and generally silent, he is assigned to protect Nena on the journey to Matamoros and serves as a reliable presence among the fighting men.

Celeste is a widow who inherited a rancho and occasionally employs Néstor. She serves as a casual romantic distraction for Néstor as he tries to outrun his grief and avoid deep attachments.

Ignacio is a vaquero at Los Ojuelos who mysteriously falls ill. Nena treats him for a cultural illness called susto and discovers a strange snake-like bite under his arm, marking him as an early victim of the mysterious creatures in the area.

Elena is a pregnant woman living at Los Ojuelos who grew up alongside Nena. She anxiously doubts Nena's healing abilities until Nena successfully revives Ignacio.

Don Severo is a neighboring landowner who brings news to Don Feliciano about white Americans claiming Texas independence and threatening to take Mexican land by force.

Javiera is Nena and Félix's younger sister. She is easily frightened by the strange occurrences on the rancho and relies on Nena for comfort during tense nights.

Susana is a lead curandero who works alongside Nena during the battle at Matamoros, treating the many wounded Mexican soldiers before tragedy strikes the camp.

Diego is the leader of a traveling group that Nena and Néstor encounter on the road. He offers them food and shelter and subtly indicates his knowledge of the supernatural threats in the area.