Originally in Fast Ships, Black Sails.
Originally from a piratical fantasy collection, Nix has some interesting backstory underpinning an assault on a seemingly impregnable fortress. There is treasure to be had, but Hereward and his small magically animated puppet, Mr Fitz, have another reason – the removal of an unauthorised godlet. There’s a cannibalistic half-leopardess pirate, lots of swashbuckling, cthulhian monsters in the deep, and a sense of it being but one adventure in the life of its protagonists, and clearly a closer link to space opera than you might think, me hearties.