Eskil's beard is clipped to a blunt, practical line, but the rest of his grooming is nearly fastidious: his hair is combed flat beneath a close-fitting cap, and he scrubs his nails with a sliver of pumice until the skin around them reddens. Fine granite dust still gathers in the creases of his knuckles and the seams of his cuffs. He moves with a mason's measured economy, turning his whole body to inspect a surface rather than craning his neck. Within a minute, people notice his unexpected habit of carrying a tiny, brightly painted wooden fish on his belt, its cheerful blue scales absurd against his grey work clothes.

Eskil is painfully honest about facts that incriminate him, yet guarded about the private grief underneath them. He can be patient to the point of tenderness while teaching a craft, but grows sharp when someone treats a route marker as decoration. In ordinary company he is reserved and dryly funny; when confronted with evidence of his brother's involvement, his composure gives way to startled, almost boyish disbelief.

Eskil learned marker-smithing from his mother in the stone-cut shops above the Abyssal Trench, where a notch in a channel marker could mean the difference between a safe return and a crew lost under pressure. He was proud of making signs legible in bad light and bad weather, and took contracts from anyone who paid for honest work. A customer with proper seals hired him to recut several route markers, giving him exact measurements and an urgent deadline. Eskil cut the stone where he was told, never asking why the new notches pointed away from established lanes. When crews began vanishing and the routes went wrong, he recognized the style and understood what he had enabled. He has since kept a rubbing of every marker he altered and sought the people who ordered the work. The ring carried by Trench-Warden Oskeld Marn is the one Eskil remembers on his estranged brother, last seen leaving for the lower trenches.