Tuck has a compact, work-hardened frame and a habit of leaning his weight onto the balls of his feet, as if waiting for a ladder to wobble. His jaw is broad and slightly forward; when he laughs, his square front teeth show in a lopsided row, and he chews the inside of one cheek while thinking. He moves in quick, economical turns, always glancing up at hooks, eaves, and lamp brackets. An unexpected detail for a lamp repairer: he keeps a tiny paper puppet tucked in his cap and makes it perform for nervous children while he works.

Tuck is warm and quick to lend a hand, but his optimism becomes an iron refusal when anyone suggests Ulla is in danger. With customers he is patient and joking; under pressure he narrows the world to the next broken thing he can fix. He is brave when protecting someone nearby, yet avoids asking for help with his own troubles.

Tuck grew up with Ulla Pritch in a cramped row of rooms above a cooper's yard, where a shared lamp was a household treasure. When their mother fell ill, he learned to mend wicks and cracked glass from a patient street lamplighter, while Ulla took whatever work paid fastest. Years ago, a fire swept through a riverside lodging house. Tuck was inside repairing a stairwell lamp when Ulla dragged him out through a smoke-choked window. He came away convinced that she could always find a way through danger; she came away furious that he had nearly died waiting for her to return. Now Tuck repairs lamps across the district and insists Ulla is merely busy, even when her absences and evasions make that explanation hard to defend. He has debts for replacement glass, a landlord threatening to clear his workshop, and a growing stack of unsent notes to his sister.