William is a slight, watchful child whose thick black hair sticks up in uneven tufts no matter how often it is combed. His startling, clear blue eyes catch lamplight sharply, giving his thoughtful face an intensity beyond his years. His skin is lightly weathered from days outside, and his boots are usually edged with dried peat. He walks carefully over uneven ground, placing each foot as if the earth has already told him where it will hold. He keeps an old brass sheep bell in one pocket and rubs its worn rim with his thumb when uneasy, an oddly fidgety habit for a child raised among formal family expectations.

William is gentle with people who give him time, yet becomes stubborn when they mistake his silence for ignorance. He notices more than he can quickly explain, and he is both comforted by his mother's care and resentful of being sheltered by it. Around patient companions he can be quietly funny; under scrutiny he retreats behind stillness. Outdoors he is decisive, while in formal rooms he doubts every answer.

William Hirst was born after a punishing labor that left his mother Mary feverish and unable to hold him for long. His father Oswin, a commanding man who rarely showed uncertainty, cradled the newborn with such care that the household remembered it. William grew up reading his mother's concealed pain and his father's silences, while wishing to be trusted rather than protected. Lessons at the manor were difficult when answers had to come quickly, but out among the sheep he could spot a lame animal, a weak boundary, or a change in weather almost at once. One winter, he wandered far from the house and was found unharmed beside a spring, with ravens gathered all around him. He could not explain how he had reached it. The incident intensified family doubts about whether he could inherit the Hirst farm. His maternal uncles Edmund and Huge question his suitability, while Mary defends him and Oswin watches him with worried, guarded attention. Lately William wakes before dawn, convinced something beneath the hill is calling. He wants to investigate, but the family fears what he might find, and Oswin's own strange night wanderings make the silence between father and son more complicated.