Primer: Neathmortality, Correspondence, Soul Trade
Back in simpler times, the soul departed with the death of the body, but death is a bit more complicated in the Neath, though not unheard of. In the Neath, death isn't quite as reliable – and certainly not as final. Those who die sometimes get back up, in a few days or in a few years. That's not to say that denizens of the Neath don't age – they certainly do, it's just that death rarely comes for them, no matter how withered they are. Those right on the cusp of true death are so decayed they're almost incapable of movement or activity, and move to distant Vindblight to waste away into nothing.
Magic is commonplace in the Neath, and what would be thought of as bizarre or fantastic elsewhere is considered quite mundane along the Neathsea. The Neath is home to a hidden smuggler's den founded by a tiger and run by cats; hidden temples woven from ice; an empire of hands, and a lost city made of tentpoles. Very few things perturb a Neathlander. One of the things that does is Correspondence.
Correspondence is a mysterious language that only the finest scholars of the Neath understand. It's a well-known fact Correspondence sigils adorn the spires of the Floating Market. It's also known that trying to comprehend the sigils can lead to madness, and that badly written Correspondence can be fatal. Some say it's a series of confidential negotiations between the Masters and a demon. They say if you read it your eyes boil and your hair turns the white of old ice. They say it's the language bats speak. They say it's the only map of the Neathsea. They say it predicts every price change in the Floating Market for the next hundred years. They say it's the mathematics of reality. They say it's the geography of Time. They say only the Brass Keep knows.