The void between worlds where the pantheon banished the feral gods — a maddening 'inbetween' that warps those who linger.
The Nothing is the void into which the current pantheon banished the Feral Gods before creating the world. Juice Box reveals that opening the Gate of the Feral Gods rips a hole into it, and lingering there destroys the mind — as it did the boss goose Denise, who "lingered too long in the inbetween. The Nothing" during her forced passage by magical gate, paying for it with her sanity.
It is both a prison for the mad elder gods and a hazard of the very portal-magic that brought so many of the bubble's misplaced creatures here.
A featureless void 'inbetween' worlds; unseen, defined by the madness it inflicts on those who cross or dwell in it.
The maddening void between worlds — prison of the feral gods and the price of gate-travel.