Seshin looks like someone the sea has tried and failed to digest. Their face is narrow, wind-chapped, and perpetually damp, with salt crusting the lashes beneath one eye. Their movements are quick but badly controlled, all sudden starts and aborted gestures, like a rat listening for footsteps inside a wall. Their hands are deft enough to tie a sailor's knot in darkness, yet they tremble whenever someone mentions the black-hulled ship. The unexpected contradiction is their immaculate fingernails, carefully trimmed and scrubbed clean despite the grime covering everything else about them. They leave behind a faint smell of wet iron and extinguished lamp oil.

Seshin is frightened, evasive, and sleep-deprived, but not cruel. They are suspicious of kindness when it comes freely and grateful for practical help they can repay. Around strangers, they perform helplessness to lower expectations. Around children, they become patient and protective. Around sailors, they turn sharp-tongued and commanding, revealing the competent deck runner beneath the panic. They are generous with information that protects others, yet miserly with any fact that makes them responsible. In moments of real danger, their fear condenses into courage so sudden that it frightens them afterward.

Seshin was born in a tidehouse beneath the eastern breakwater, the second child of a rope-maker who drowned before Seshin learned to swim. They became a dock runner, then a thief, and finally a smuggler aboard the black-hulled ship called the Gannet Below. At first the crew carried ordinary contraband: forbidden spices, stolen relics, fugitives, and sealed letters. Three weeks ago, the captain opened a lead-lined crate during a storm. Inside was an occult relic wrapped in whale hide, a thing that pulsed like a sleeping heart and leaked black seawater upward against gravity. The ship's crew began hearing voices from beneath the waves. Seshin escaped by cutting a cargo net and falling into the harbor, leaving behind their closest ally, the tavern lookout Jorren Pell. Since then, Seshin has rented a room above the Drowned Lantern, accrued a debt to its keeper, and threatened the owner of Brinehook Salvage into hiding the relic. Their current problem is that the captain knows the relic reached town and has sent drowned-looking deckhands to retrieve it. Seshin wants to flee through the storm drains, but guilt keeps pulling them back toward the people they abandoned.