Overworld: The normal world where Humans descended from the beings that committed a crime against were sent to live out.
Underworld: Humans who have not 'fallen from grace' and where they live peacefully. This world is an inverted version of the Overworld; the vast oceans and the deepest trenches becomes the tallest mountains and the biggest land mass.
Aether: The barrier that ensures that both worlds were to destroy one another. Only Death can enter and exit this world.
Imperium: The foundation of power in this world; a catalyst that would allow only certain people to interact with beings of other worldly origins. It allows them to control the 4 elements and enter a the Underworld and everything that connects to it. People who posses this are called Misfits by their own kind.
Dark Imperium: A much more unstable version of Imperium that is created with darker influence from the demon. Also known as the Corruptor.
The Call: Mistaken and called as 'Awakening', it is the mysterious feeling that a person with Imperium will feel. It will attract them to a Reaper's home, mostly a establishment in order to keep a low and human profile. It tends to be strange whispers or attraction to certain places, or just stumbling upon it unconsciously.
Awakening: It is the sudden burst of Imperium, it is when the Misfit hits their lowest physically, mentally, and emotionally. Since it is seen as a damage Imperium will burst through trying to 'repair' it; Misfits can have this Awakening during their 'Call'.
Lower-demons/ minions: Weaker demons that has been casted down to hell by Death or dragged down by the demons with the usage of their temptations to corrupt them and add them to their legion.
Altered Ones: Mythical or Legendary creatures of supernatural or paranormal phenomenon realized by the belief of the people to that being and with dark imperium. Places that associates its history with legend or folklore tend to be the most active places for Altered Ones to appear in.
Psychopomp: Guide of souls. These are created by Death in order to guide souls to the purgatory. These souls are bounded by the 'Reapers Oath' that makes them forget their past and along with it their emotions. If somehow a 'reincarnate' (people from their past life that were significant to them) meets up with them, their attraction can cause their very own death unless they stop it. They have unfulfilled mission in their past life and Death asks them to complete only in a different way. They will be reincarnated once they have completed Death's task for them.
There are some cases where Reapers have created a horrible crime in their past they become Reapers automatically, Death will give them a 'Divine Punishment' as a way to make sure that their 'Oath' will not be broken and they can be 'reincarnated' themselves once the Oath is fulfilled. The fulfillment of the mission will be signified by a dove's feather; and a failed one will be signified by a crow's feather.
The Angel Of Death: 1 Angel that is created by Death itself who sits by the Bridge of Souls watching over them. The Bridge of souls is connected to the Purgatory where Death shall judge them.
Angels of Death: Strongest type of Reapers; this beings are able to kill and hunt down Altered-ones or Minions; they can also go up against demons. They also are able to segregate the type of soul, they can create Reapers and Ghosts with their book and quill.
Grim Reapers: Reapers who have existed for over a millennia or have 'sealed away' 1 thousand souls. They cannot fight and can only judge and take souls; if they were to break the Oath and fight they have at lest 24 hours to finish their mission and die away.
Reapers: They are half the strength of a Angel of Death; they can fight Altered ones and Lower-demons only. They can also 'judge' souls. Cannot make other Reapers. Like Misfits all 3 have imperium.
Pyschochomps Devices: These are the primary items used by the 3 beings. They can also manipulate memories.
Domain Clock: A stop watch that can be used by the Reapers to enter the Aether to ensure that the real world is not damaged. It stops time and they have up to 12 hours in order to defeat the being they trapped; if it lasts longer than the given time it will create a rife on the Aether.
Book and Quill: A book with infinite pages where the souls name and 'punishment' will be given. Reapers can turn the souls into Ghosts or sent to the purgatory in order to be judge. They use the blood of that soul in order to write their names down.
Concealing Item: An item that was of significance to the Reaper; such as wedding ring, top hat; or the stopwatch itself.
Gate: The Reapers Omnipresent abilities are shown in this way; they will use doors no matter how random even a man-hole in order to go to where the soul is.
The Reapers Oath: An Oath created by Death to ensure that his Reapers will do as they are told; they will not remember them participating on this conversation and along with it their past memory. It also locks away their emotions and the feeling of pain.
Angels: Beings made with Good Graces.
Supreme Angel: only 1 of them exist and they are the epitome of power when it comes to them.
Archangels: There are only 4 Archangels but people also consider it to be 14. They mostly stay in the Overworld and ensure balance between good and evil. Their omnipresent ability are shown by their influence over the humans in both worlds.
Guardian Angels: Angels who are given the grace in order to live until the end of the world; and at the same time it also grants them power.
Demons: Fallen Angels, corrupted by something; it allowed them to be stronger than the angels but they were all casted down to hell. But they influence stays in the humans in the form of temptations. They are much stronger than the angels naturally but they are dying and in need of souls to feed off of; but because of the aether and the authority of the angels they are only at their strongest in hell.