Lou is an assertive 12-year-old girl who aspires to be a writer like her father. Following a devastating car accident that leaves her family fractured, she moves to the Virginia mountains to live with her great-grandmother. She relies on pragmatism and facts to cope with her new reality. She initially struggles to adapt to the physical hardships of rural life and harbors skepticism toward her brother's magical thinking.

Oz is Lou's seven-year-old brother. He possesses an active imagination and a deep capacity for hope. Following the family's tragic car accident, he refuses to accept the permanence of their situation. He actively tries to cure his mother using a quartz necklace and earnest wishes, serving as an emotional counterweight to his sister's strict reliance on facts.

Louisa is Lou and Oz's formidable eighty-year-old great-grandmother. She has survived decades of hardship on the high rock mountains and treats her farmland with deep reverence. Having raised her grandson Jack after his own family fractured, she steps in once again to provide a home for his orphaned children. She manages a demanding agricultural life despite her advanced age.

Cotton is a transplanted Bostonian who moved to rural Virginia to escape the shadow of his famous ancestor, Henry Wadsworth Longfellow. He works as a country lawyer and befriends Louisa and her newly arrived great-grandchildren. He takes a particular interest in Amanda's condition and begins reading aloud to her in hopes of sparking a recovery.

George is a harsh, ill-tempered landowner whose property borders the Cardinal farm. Despite his relative prosperity, he forces his own family to live in squalor while he hoards his agricultural yields for profit. He reacts aggressively to anyone trespassing on his land and views the mountain solely as a resource to be exploited for personal gain.

Jack is a critically acclaimed but impoverished author who left the Virginia mountains in his youth to pursue a writing career in New York. His sentimental novels reflect a deep nostalgia for his childhood home. A sudden car crash cuts his life short, leaving his children to discover his roots by moving to the very mountains he wrote about.

Amanda is Jack's wife and the mother of Lou and Oz. Shortly after begging her husband to return to the Virginia mountains instead of moving to Hollywood, she survives a horrific car accident that claims his life. The sheer shock of the event plunges her into a catatonic state. She remains physically present but mentally absent as her children transport her to her husband's ancestral home.

Eugene is a lame Black man who works the farm alongside Louisa. Abandoned as a baby by his father, he was raised by Louisa and remains fiercely loyal to her. He serves as a steady, quiet presence on the homestead. He patiently teaches Lou and Oz how to manage morning chores like milking cows and slopping hogs.

Diamond is an orphaned teenager living alone in a mountain cabin following the deaths of his parents. Possessing a folksy charm and a deep familiarity with the local wilderness, he quickly befriends the Cardinal children. He introduces them to a hidden wishing well and shares local lore. He acts as their guide to the mysteries of the high rock.

Billy is George Davis's eldest son and a student at the local school. Growing up in a deeply abusive and impoverished household, he acts out his frustrations by bullying his classmates. He specifically targets the Cardinal children because of their Northern origins and their father's literary reputation. This animosity leads to physical altercations with Lou.

Estelle is the sole teacher at the one-room schoolhouse that serves grades one through seven in the mountains. She struggles to maintain order among her diverse group of students, many of whom frequently miss class to help with farm work at home.

Hugh Miller is an executive representing commercial interests looking to exploit the natural resources of the Virginia mountains. He approaches the Cardinal family with lucrative offers to buy their land, viewing the landscape solely as a source of profit.