At first glance Jeremiah passes for a lean human man in his twenties, but his face seems too still when he listens and his pupils narrow to fine vertical slits in sharp light. His skin has a faint, pebbled sheen at the temples and along the throat, like rain on river stone. He moves with careful, low-footed balance, placing each step as if a deck might tilt beneath him. His patched work coat hangs badly at one shoulder, while its brass collar clasp is polished with almost ceremonial care. Within a minute, most people notice him thumb-checking that clasp whenever a door opens behind him, an oddly domestic habit for a famously capable infiltrator.

He is wary and analytical with strangers, but unexpectedly generous with people who are frightened or out of their depth. He wants to be seen as competent and self-sufficient, yet he takes deep comfort in being included in ordinary routines. When calm, he is patient and exacting; when worried, he becomes controlling and buries everyone in contingencies. Anger makes him blunt and immovable rather than loud, while embarrassment brings out quick jokes and busy hands.

As a young teenager, Jeremiah came down in a burning fragment of a spacecraft onto Sonoe QHMX. He remembers the impact in sensations rather than sequence: a sky that flashed white, the taste of hot insulation, and the deep quiet after the alarms failed. Floria found him among the wreckage and argued for sanctuary on Ariez Island, where the worldtree settlement Sylvarae took him in. He learned its paths, its customs, and how to make alien components serve local needs. At first he built devices to keep people at a distance; after a winter storm trapped several families in a damaged canopy bridge, he climbed out in the gale to repair its anchor. The rescue changed his idea of what useful meant. He now maintains lifts, pumps, and protective mechanisms around Sylvarae, while secretly rebuilding a receiver from the ship's remnants. He is close to Floria, who gave him a home but worries that his curiosity will bring danger to it. His current conflict is with Hask, a surveyor who wants the recovered wreckage surrendered for study, and with his own uncertainty about whether anyone from his old life is still looking for him.