Sessa stands with her weight planted on the outside edges of her boots, as if bracing against a floor that might suddenly lurch. She has a broad, practical face, a strong jaw, and square teeth with a conspicuous gap between the front pair; when she eats, she tests each bite with a small sideways grind before committing. Her movements are economical but never still: one shoulder rolls, a thumb checks a seam, a boot nudges a loose fitting back into line. Her unexpectedly lovely habit is keeping a tiny window box of violets on the shop's soot-black forge ledge, fussed over with the same concentration she gives a precision valve. People leave with the impression of a doorstop that learned to laugh.

Sessa is blunt about bad workmanship but tender with anyone who is trying in earnest. She likes being the person others rely on, yet resents being treated as an endlessly available tool. In a crisis she becomes brisk and daring; in a quiet room she can be awkwardly sentimental. She enjoys a clever joke, though she will often explain why it works afterward.

Sessa learned repair work from her mother, who kept the sluice gates and water clocks of a river town running. At nineteen, Sessa was on shift when a neglected floodgate jammed. She chose to save a trapped apprentice rather than obey the foreman's order to hold the mechanism in place; the gate broke, the lower workshops flooded, and her mother lost her livelihood. Sessa spent years paying back the damages and learning to build devices that fail safely. She came to the city with a battered tool chest and opened The Humming Brace in a converted pump house. Her mother, Hesta, now lives upriver and writes only when she needs a repair. Sessa's former teacher, Dannel, sends her customers but resents that she has made a living from careful work instead of joining his costly engineering consortium. A recent run of stolen parts has left her shop short on supplies, and the humming in the old foundation has become too regular to dismiss as pipes settling.