Galdan has a broad, weathered face, a blunt nose, and a habit of pausing with his lips parted as if tasting the air before he answers. His stride is slightly lopsided from years of carrying a heavy still on his left shoulder, but his hands are quick and exact when measuring powders. A small, unexpectedly polished brass toy horse dangles from his belt, carefully wrapped against spills; it belonged to his daughter. He leaves the impression of a practical man who has made room for one stubborn tenderness.

Galdan is patient with the frightened and impatient with the careless, yet his sternness often hides a deep fear of making another mistake. In a crisis he becomes brisk and commanding; when alone, he frets over small choices and fusses over his equipment. He believes remedies should be shared freely, but resents anyone who treats his knowledge as if it cost him nothing.

Galdan was raised among reed cutters on the edge of a floodplain, where his mother taught him which plants soothed fever and which merely hid it. He left home to apprentice with a traveling apothecary, then returned after a spring flood poisoned the village wells with runoff from a dye works. His first attempt at a mass remedy was badly measured; it saved many people, but his younger brother was among those who took it too late. Galdan spent years learning druidic rites from a marsh hermit and refining his craft until medicine and nature stopped seeming like rival explanations. He now treats the sick at a roadside shelter and quietly tests the water upstream. His former teacher, Vorka, wants him to sell a potent preservation formula to a wealthy river factor. His daughter, Dena, lives with her other parent in a market town and believes he chose his work over her. He sends her letters and small carved animals, none of which he has managed to deliver in person. The floodplain is suffering another strange die-off, and Galdan suspects someone has resumed dumping waste into the river.