Wesseth, known on the road as Critter, is a wiry human with the compact, spring-loaded posture of someone accustomed to slipping through broken fences and animal stalls. His close-cropped hair is combed with such exactness that the part remains sharp even after a night outdoors, while the rest of his kit is patched and weather-worn. He moves with little wasted motion, pausing at thresholds as if listening through the soles of his boots. Within a minute of meeting him, people notice his eyes: they travel first to exits, then to hands, and only last to faces. His expression is alert but not cold; he watches people the way a kennel keeper watches a roomful of nervous dogs.

Wesseth can be tender and patient with a frightened creature, then briskly unsentimental with the person who frightened it. He is generous with food and labor but guarded about his past. In calm company he makes dry observations and lets others take the lead; under pressure he becomes decisive, even reckless. He wants people to think him practical, though his conscience repeatedly makes impractical demands.

Wesseth grew up in the cramped animal yards behind a river-market, where he learned to read fear in a twitching ear before he learned his letters. As a young adult he worked for the warning-named kennel, Keep the Gate Shut, catching strays and escorting dangerous beasts for traveling handlers. During a winter transfer, the handlers' cart overturned on an iced bridge. The chained animals panicked, and Wesseth had to choose between obeying his employer's order to save the valuable cargo and opening the cages before the animals drowned. He cut the locks. Several beasts escaped, and his employer's nephew was injured in the crush. Wesseth still believes freeing them was right, but he carries guilt over the person hurt and the animals he could not reach. He now travels as a tracker and discreet rescuer, returning lost animals and quietly sabotaging cruel transport jobs. He sends most of his pay to the injured man's family, who have never learned who made the payments. His former coworker, Salk, is trying to find him before the kennel's owners do.