The Gatekeeper is a being who is embedded into a door that leads the soul of a dead being into either The Lightness or The Darkness. It is thought that when one dies, they will come across a grassy field on a cloudy day with no hills or trees. They will meet the Gatekeeper who will judge them of their life when they were living. If he accepts it, he will open the gates to the Lightness. If he denies, he will open the gates to the Darkness. There is no in-between.
Although it is unknown to be possible or not, it has been said that upon meeting the gatekeeper you have the option of running away, however, you will be stuck in the realm of the Gatekeeper. It is also possible that once you run away, you may never find the Gatekeeper again, thus wandering in nothingness for eternity, and causing imbalance to every existing plane.