Mary is a fair-skinned, blue-eyed young woman with wheat-blond hair usually braided close to her head. Her face is open and capable of startling warmth, but she watches doorways before she looks people in the eye. Her wool sleeves carry a faint lanolin smell, and a narrow shuttle-shaped wooden charm hangs at her throat; its lower edge is polished smooth from years of anxious thumb-rubbing. She moves with the guarded economy of someone carrying a sleeping child, even when her arms are empty. When rattled, she takes short, shallow breaths that catch audibly behind her teeth. The unexpected thing about her is that she keeps a little paper notebook of bird calls and can identify many by ear, a quiet pleasure unrelated to her domestic work.

Mary is tender and observant, yet suspicion sharpens her whenever night or the supernatural enters the conversation. She is patient with children and neighbors in daylight, but becomes controlling when William is out of sight after dusk. She can laugh freely about ordinary mishaps, then abruptly retreat behind careful questions if someone mentions the wedding night. She wants to trust Oswin and actively watches him for signs that trust is foolish.

Mary was raised in a hamlet where winter stores, shared labor, and the gossip carried between looms mattered as much as coin. She learned weaving from her mother and took pride in making sturdy cloth that lasted. She married Oswin because she loved his dry humor and the way he could make a difficult day feel survivable. On their wedding night, Oswin deceived her about what happened: a Barguest, a dark folkloric creature, came to her in his guise and consummated the marriage. Mary remembers the terror and intimacy of that night, but Oswin has never told her the truth. She has told her father, and her brother knows something of it in passing, though neither has the full account. Mary believes her young son William was fathered by the Barguest. William is slow to meet milestones, and his black eyes burn an uncanny blue in certain light. A later baby died soon after birth, frail and feverish; since then Mary has struggled to carry another child to term. She loves Oswin as the man she remembers and fears the creature she believes he became. When the season turns toward fae and demons, she keeps watch over husband and son, bars the shutters, and loses sleep. Her current problem is not just fear: she needs the truth, but fears that learning it will destroy her family or confirm that William is in danger.