A place between places, the manifestation of a personal heaven and hell built upon a stolen chunk of purgatory. Both parallel and perpendicular to heaven ,hell ,the veil and purgatory.
It shares the rules of all realms which often contradict each other, like a lucid dream. It is infinite but only has a certain area stable enough to exist in without falling into the empty. All are equals within, within it you are neither alive or dead but killing or giving birth to life within it to something that did not originate in it will kick out said being to there respective place. If the being has a vessel within a stable realm they are returned to said vessel, if a being is within there own vessel they may die and be sent to heaven hell purgatory or the empty or they may be returned to a stable plain by the porter or doorkeeper (who was originally human but discovered the middle). It is a place where you may create and bring said creation to reality or may access alternate realities.
It is a place where even god, death and the darkness avoid because of its rules and lack of them. A place where even they may die. It is possible to fish souls out of the empty if you can find them and they returned to life.
It has a few physical solid locations from the keepers nightmares and dreams as well as the physical manifestations for the outside of God's bar and deaths library although they do not exist within it.
It contains the doorways and gates to all places and times excluding the garden of eden(although souls may be restored or made with in). It is the place where dream walkers walk.
The doorkeeper only has his power over the place because of his primitive understanding of how the place works, but it has knowledge of the unknown even to God within it and contains a hidden "reset" button for existence including the light and the dark .
Being within the place may cause the being to go insane and "zero out" from knowledge and understanding destroying the beings mind if unable to handle the truth of the natural order.
It is the origin of soul eaters, their nest exist outside of the "safe space" , it is the cause of Schizophrenia. It is the only place capable of destroying souls although they usually run off the side or follow one of there manifestations of of the edge. It's also the origin of the tulpa beings although the sigil needs to be present in order for them to be drawn out of the middle.