Oswin stands six feet tall, handsome in the way of a carefully carved church figure: pale, smooth-skinned, straight-nosed, with a youthful face that seems strangely untouched by passing years. His blond hair lies in straight, fine strands beneath a common flat cap, and his clear blue eyes hold a bright, furnace-like gleam when the light is low. He moves with a farmer's economical stride, but rarely plants both feet squarely; while waiting, he rests his weight on the balls of his feet, as if ready to cross a field at a run. His shadow sometimes has the long, lowered head and heavy shoulders of a hound even when he stands upright. Unexpectedly for a wary livestock owner feared as a beast, he keeps a tiny painted wooden lamb in his waistcoat pocket and rubs its worn ears with his thumb when anxious.

Oswin is kind in action but evasive in speech: he will mend a neighbor's wall before dawn, yet answer a personal question with a weather report. He is practical and shrewd about land, animals, and money, but unexpectedly tender with William. In safe company he can be wry and sociable; during haunted seasons he grows watchful and restless. He longs for the road while fiercely maintaining the domestic life he chose, and that contradiction leaves him both grateful and quietly resentful.

Oswin says he was born among the Yorkshire dales, learned sheep work from his father, and settled into a respectable life after years of wandering. The truth is older and less tidy. He is a Barguest, a shape-changing spirit of the roads and dark fields, and his memories of his roving days come in broken, contradictory fragments. He remembers a winter lane, a lost traveler, and the red eyes of something that may have been himself. When he first courted Mary, he tried to approach their wedding night in human form and failed in a way he cannot explain without admitting how little he understands human intimacy. Later that night, while Mary slept, he took the form of a headless man with red, saucer-bright eyes and consummated the marriage. Mary woke with no clear memory, only terror, and has long believed a Barguest violated her. Oswin has never told her it was him. She once cut him with iron scissors, and the shock of her fear affected him more than any wound. Their son William was born with black hair and Oswin's burning blue eyes, and is slower to speak and learn than other children his age. Mary calls him Black William, sometimes Blackby, and privately fears he is the devil's child. She does not know Oswin's nature or the truth of that night. Her father, a suspicious man, has heard enough of her account to watch Oswin closely. Mary has also suffered other failed pregnancies, which Oswin privately fears are connected to his unnatural nature. He owns a fine farmhouse and a good flock, tends both with shrewd care, and deliberately sets aside time each day for Mary and William, even when certain seasons bring sleepless nights and strange sounds across the dales. He dreams of his old wandering life, then wakes ashamed that he misses it.