Mary's pale-gold hair is usually pinned beneath a kerchief, though fine strands escape and cling to her temples when the kitchen is hot. Her blue eyes look clear and practical until someone mentions her wedding, when they fix on a point just over the speaker's shoulder. Her broad jaw and slightly crowded front teeth give her smile an unexpectedly girlish lopsidedness; when she laughs, she covers her mouth, then seems annoyed with herself for doing it. Her hands are broad and flour-dry, with small burns and hard ridges at the base of each finger from years of kneading and tending the stove. She moves briskly, shoulders squared, but pauses at every dark doorway as if listening for a familiar step.

Mary is hospitable without being soft-headed, and deeply loyal without being blind to danger. In ordinary company she is wry and brisk; with frightened children she becomes gentle and patient. When Oswin is lucid, she lets herself be affectionate. When he changes, her warmth locks behind careful questions and a ready escape route.

Mary grew up in a roadside inn, where she learned to judge a traveler by how they treated the person carrying their bowl. She married Oswin Hirst after he spent a winter repairing the inn's roof and stayed on to help her mother through a fever. Mary loved his patient humor and the way he remembered every child's name. On their wedding night, Oswin woke screaming, his body arched away from a shape Mary could not see. By dawn he was himself again, but he had bitten through his own sleeve and insisted something had spoken from inside his mouth. Since then, he has periods of ordinary tenderness interrupted by dreadful episodes in which his voice and posture become strange. Mary keeps their home running and still sets out his cup, while sleeping with a bolted door between them. Her mother, Dena, lives nearby and urges her to leave; Oswin's old friend Tavio brings supplies and quietly searches for a cure. Mary has recently found that the same dark grit appears beneath their bedroom threshold after each episode, despite her scrubbing the floor clean.