The nothing was this patch of nothingness that was popping up all over Fantastica and growed endlessly.
Those near the nothing felt an uncontrolable urge to throw themselves into it, and the more it absorbed the faster it expanded. The rate of it's expansion grew exponentialy.
The Nothingness was created by Humans who lied, because lies are made up of converted Fantasticans, and whenever you tell one, the nothing absorbs some of the essense of Fantastica and gives it to your mind. The less people who believe in Fantastica, the more Unstoppable the Nothing becomes.
No being in Fantastica can affect the Nothing, only Humans can, by giving a New name to the empress (Which restarts the story).