The Nix is a flux anomaly that lives in the Wyldewode. Known to locals as a friendly forest spirit, it will watch over a household if milk is left out for it in a specially made “Nix Bowl”. The Nix is a watery sort of spirit and has a peculiar love of stories - sometimes, when Wyldewode children are gathered to hear a tale spun by one of their village elders, the Nix can be glimpsed, watching and listening from the shadows in the corner of the room. It is adept at navigating the flux and has been known to guide travellers into Lost Places, following the stream of a story back to its source.

In The Way through the Woods, a group of adventurers introduced it to the idea of making a new story, an idea that simply hadn't occurred to it before. In Written on the Leaves, it tried to fashion the perfect story (the Monomyth, as the Nix referred to it) out of the Yarn. It subsequently trapped a number of people within the story, unaware that it had done anything wrong until an adventuring party had a quiet word with it. Expressing regret for its actions, the Nix seems to have gone back to its roots as a household spirit, and is currently being kept busy at The House That Jack Built.