Oswin stands exactly six feet tall, handsome in the unnerving, well-kept way of a face that time seems to have forgotten. His skin is pale, with a cool, almost waxen cast after sleepless nights. Straight blond hair falls neatly to his collar beneath a common flat cap; his burning blue eyes seem too bright in dim rooms. He moves with a farmer's economical certainty, but every so often his weight shifts onto the balls of his feet as if he might break into a run on four legs. His unexpected softness is a tiny, carefully mended patch of blue wool sewn inside his cap, a remnant from a child's blanket. People notice how cleanly he dresses for a sheep farmer, and how his shadow sometimes seems to have a muzzle.

Oswin is gentle in daily life but not harmless: he will patiently mend a gate, then answer a threat with the cold certainty of a predator defending its den. He is practical and shrewd about money, weather, and people, yet foolishly sentimental about the home he has built. With Mary he is tender and attentive, but the more she fears him, the more carefully he edits the truth. With William he is playful and patient, though his protectiveness can become suffocating. Alone, he grows restless and nostalgic for his roving days.

Oswin says he was born among the Yorkshire dales and learned sheep-work from his father. That story is close enough to truth to survive casual questions, but not close enough to explain why he remembers old field boundaries that no living farmer has seen. For years he roamed as a black hound through moorland lanes, drawn to crossroads, funerals, and the nights when the unseen world pressed close. He grew tired of being feared and settled into a respectable life as a livestock owner, buying a fine stone house and a flock with money accumulated over a much longer life than he admits. He met Mary while trading sheep. He wanted a human marriage, but on their wedding night his human body failed him in the intimacy he had hoped for. Ashamed and afraid of losing her, he took his hound-like, headless Barguest shape while she slept and consummated the marriage. Mary remembers a headless figure with red, saucer-bright eyes, and fears she was visited by a devil. Oswin will not tell her the truth. She once slashed at him with iron scissors when he startled her in the dark; he recoiled, but she did not see how deeply the moment bound him to her. Their son William is slow to speak and think for his age, with black hair despite both parents' blondness and Oswin's unmistakable blue eyes. Villagers call him Black William or Blackby. Mary believes the boy is the Barguest's spawn. Oswin spends every possible daylight hour with Mary and William, even after sleepless nights, but certain seasons bring old supernatural activity and leave him pacing until dawn. Mary's father, whose name Oswin does not know she has disclosed, suspects that his son-in-law is not human. Oswin dreams often of the dales as they were before fences, roads, and familiar names.