Pethis is a compact, weather-browned human woman with a patient, forward-tilting gait, as if the ground might shift underfoot. Her movements are economical until she spots a current, when she turns her whole body to follow it. A tiny brass fish, polished nearly flat by decades of her thumb, hangs from a cord at her throat; she rubs its worn tail whenever she is thinking. Unexpectedly, she keeps a pocket-sized collection of pressed marsh flowers tucked inside her chart case, each carefully labeled.

Pethis is methodical with routes and generous with people, yet distrusts confident assurances even from those she loves. In a crisis she becomes brisk and decisive; in a calm room she can be unexpectedly playful, especially when showing someone a rare flower. When ashamed, she retreats into technical corrections instead of admitting what hurts.

Pethis was raised among the reed-island camps of Siltwake, where her mother taught her to read water by its smell and the angle of floating seed husks. As a young chart apprentice, she trusted measurements more than instinct. During a spring flood, she followed a copied map into a channel that had silted shut. Her younger brother, Tavi, drowned in the overturned boat. Pethis survived by clinging to a marker post and listening for the current beneath the storm. Afterward she began leaving deliberate blanks on her charts wherever water could not be trusted to stay put. Vael Orison later used her early surveys as the basis for his own charts; she respects his craft, but resents that people praise his copies while calling her blank spaces an insult to navigation. She now maintains a small chart room on a floating platform and is trying to persuade the Siltwake pilots to stop treating old routes as promises.