A pale, solemn toddler with a cap of unusually black hair and Oswin's bright, burning blue eyes. His hair grows in dense, straight tufts that stick up again soon after being smoothed. He moves with a careful, slightly lopsided toddle, pausing to study thresholds and shadows before crossing them. His grooming is conspicuously deliberate: Mary keeps his hair neatly combed, though one stubborn lock always falls over his brow. People expect a lord's heir to be presented like a miniature adult; instead, William often has a smear of porridge on one cuff and a wooden animal clutched in his fist.

Watchful and slow to warm, yet intensely curious once he feels secure. He resists being hurried, but seeks closeness when frightened. He can seem remote in a crowded room, then become stubbornly attached to a small toy or familiar routine. His long pauses reflect his own pace, not a secret plan or deliberate refusal.

William was born after a long, exhausting labor that frightened Mary and left the household waiting outside the birthing room in silence. He emerged with black hair and Oswin's striking blue eyes. Oswin held him with a care so solemn that even the servants fell quiet. As William grew, he spoke and learned more slowly than other children his age. His maternal uncles, Edmund and Huge, and his maternal grandparents worry that he may not be capable of inheriting the responsibilities expected of him. Their concern is practical, but it lands on Mary as a judgment of her son and on Oswin as a threat to the family's future. Mary has begun keeping notes on the words and gestures William does learn, while Oswin has quietly asked a trusted household tutor to observe him without turning every meal into an examination. William's present world is small: familiar rooms, familiar hands, and the adults who argue in careful voices just beyond his hearing.