Uiseth is a weather-cut man with the compact, economical movements of someone who has spent decades climbing where a misplaced heel means death. His sun-browned skin is crosshatched with pale flecks from windblown grit, and his dark hair, now heavily threaded with silver, is tied back with a strip of old sailcloth. His eyes are a clear, unshowy gray-green, always measuring ledges, hands, and exits. His broad palms are ridged and shiny with callus, the nails permanently darkened by stone dust; he keeps rubbing the knuckle of his left thumb as if checking an invisible buckle. His boots are polished smooth at the toes from scrambling up rock. For a man who claims to have abandoned the world below, he has an unexpectedly meticulous habit of folding tiny paper birds from any scrap placed in his hands. He moves with a slight forward lean even on level ground, leaving the impression that the ground is merely a temporary arrangement.

Uiseth can be generous with food and brutally economical with hope. With strangers he is dry, observant, and unwilling to flatter; with frightened climbers he becomes patient and unexpectedly gentle. In a crisis he is decisive to the point of seeming cold, then later replays every choice as if there were still time to change it. He values companionship but has built his life around making himself impossible to accompany.

Uiseth grew up in a wind-battered valley where the mountain called Zenith stood above the clouds and supplied the river that kept his home alive. His mother, Nessa, maintained the old trail markers; his younger brother, Bryn, hauled supplies for climbers. Uiseth first climbed for pay, guiding a survey party that vanished in a storm. He survived by wedging himself inside a crack for two nights, listening to the lost party's signal bells fade one by one. When he finally descended, he found that the valley's spring had shifted course and his family had moved away. He became a ranger, learned to read the mountain's strange weather, and returned years later with a small climbing crew. At the upper ridge, a sudden avalanche threatened to take the crew and a group of strangers below. Uiseth cut the party's safety line to anchor the falling snow with an old fey charm, saving the valley but stranding himself above the cloudline. The crew descended without him. He has remained at the summit for twelve years, where the sky bends oddly and the path down seems to rearrange itself. He still sends messages down in paper birds. His mother is dead, his brother has become a respected bridge-builder, and his former climbing partner, Huw, keeps trying to reach him despite Uiseth's warnings. Now the mountain's spring is failing again, and Uiseth has begun to suspect that his long vigil is not protecting the valley but keeping something beneath the summit awake.