Oswin stands exactly six feet tall, pale and straight-backed, with a handsome face that has scarcely changed since Mary first saw it. His blond hair lies sleek and straight beneath a common flat cap, but at the temples it catches light like dried straw. His blue eyes are vivid and steady, with a cold inner brightness that becomes unmistakable when his temper or hound nature rises. He moves with a farmer's economy, placing each boot as if testing boggy ground; when startled, he turns his whole body toward a sound rather than merely his head. His wool clothes smell faintly of lanolin, peat smoke, and rain. A small iron scissor nick in the leather of his belt is easy to miss, but he never lets the scissors themselves touch him. The unexpected detail is his meticulous habit of keeping a child's slate tucked in his coat, its corners polished by his thumb.

Oswin is tender in private but guarded in public, practical about hunger and weather yet haunted by questions ordinary folk do not ask. He can be dryly humorous while mending a fence, then become remote when the season turns strange. He is devout and sincere in church, though stiff among its ironwork. He wants Mary to trust him, but his shame makes him withhold the very truth that might let her do so.

Oswin was born in the Danelaw, the son of a woman assaulted by Viking raiders. He remembers being a normal, frightened child until his mother died and he discovered that the years were passing over him differently from everyone else. Long afterward, he learned that he could wear the shape of a black hound and that something from the boundary between the mortal world and the fae had marked his blood. He roamed for centuries, learning Old Norse, Anglo-Saxon, and scraps of other human tongues, while refusing to speak the forbidden languages he encountered beyond the boundary. Eventually the dales pulled him back. He made a practical life as a sheep farmer, saved enough for a fine house for his station, and married Mary Pickles. On their wedding night, he failed to consummate the marriage in human shape. Afraid of losing her and unable to explain himself, he took his hound form. Mary fought the beast with iron scissors, then spent the years since believing a headless Barguest with glowing red eyes had visited her. Oswin has never told her the beast was him. Their son William, called Blackby by locals, has black hair, his father's burning blue eyes, and a slowness in learning that Oswin fears may be the first visible sign of their mixed blood. Mary believes the boy may be the Barguest's child. Oswin and Mary have also lost their daughters Alice and Rose before birth, and a baby son whose hellish eyes Oswin saw before he died. Mary does not know Oswin saw those eyes. Thomas Pickles, Mary's father, suspects the truth; he once saw a black hound near the family and lost his eldest daughter Alice to a winter fever. Mary's brothers Hugh and Edward remain close enough to notice how little Oswin changes. Oswin keeps working, tends his family, and takes time with William even when seasonal visitations leave him sleepless. He has friends among the beings beyond the boundary, but the old roads still call to him.