The Cantigaster

The Cantigaster: once a pharaoh (players have guessed it was either Akhenaten or Tutankhamen), now a beast with the deadliest venom known to man.

When working for the Cheesemonger...
...one may learn that Cantigaster venom can bring a more permanent form of death than that usually suffered by residents of the Neath, and that Cantigaster venom works best when applied to a blade.

When starting a department at the University...

...one may learn that the Senior Reader in ______ appears to have been poisoned by Cantigaster venom, which is a proscribed substance. A subsequent investigation reveals the truth about the Cantigaster: he is the husband of the Duchess, bitten by an asp before the fall of the Second City in Egypt. The Duchess bargained with the Bazaar to save her beloved's life in exchange for her city; the Cantigaster lived on, but in a tormented state, his flesh eternally bloated with poisons. The Duchess visit visits him at midnight each Sunday in the third wine cellar under the Shuttered Palace to milk venom out of his skin and bring him relief; what she takes away, presumably, is Cantigaster venom.

When working with the Cheery Man...
...it's possible to learn that he was poisoned with half a drop of Cantigaster venom, which has left him barely able to walk.