Billy looks as if he has been assembled from dock pilings: broad through the shoulders, thick-waisted, and planted so firmly that people unconsciously step around him. His hands are unusually broad and blunt, the palms crosshatched with old rope calluses and stained dark at the creases by tar. He moves with a careful, rolling gait, testing the floor before trusting it. A pale fringe of reed fuzz often clings to his cuffs, and he smells faintly of river water, smoke, and boiled apples. Unexpectedly for a veteran guard, he wears tiny, neatly mended knitted booties on his pack mule's hooves to keep them quiet on stone.

Billy is blunt and steady in a crisis, yet awkwardly tender with animals and children. He can be patient with a frightened stranger and stubborn with a well-meaning official. In a quiet mood he jokes about his own bad knees; when guilt rises, he becomes all work and no conversation.

Billy grew up on the flood-prone banks of the Morrowwash, where his mother, Sella, ferried people across and taught him to read water by its sound against pilings. He joined the town watch for a steady meal and became its best shieldman. During the disastrous spring flood of 1487, a panicked order sent him to hold a gate shut while families were still trapped on the wrong side. He disobeyed, broke the gate, and saved twenty-three people, but the flood wrecked the lower ward and killed his closest friend, Olek, who had stayed to help. Billy still carries the snapped gate's iron hinge as a reminder that orders are not the same as judgment. Now he guards barges and travelers while trying to persuade the council to rebuild the river's neglected spillway. His sister-in-law, Vima, thinks he should stop risking himself for a town that keeps delaying repairs; he quietly sends money to Olek's daughter, Neri, who believes her father died because Billy left him behind.