Demons are the essence of mortal beings, developed into various forms depending on their spiritual makeup and level of acquired consciousness. All demons were once benign, but many have become corrupted by human or animal interference. Demons do not experience time linearly as they wander a mysterious realm parallel to the earthly world.
Nature and Origin
When a mortal creature dies, its life force dissipates into a wisp of energy- essentially a soul- which lingers in an undetectable higher dimension, namely the "demonic realm." Demons are the culmination of this energy. A demon's structure can range from that of a thousand souls, compacted into a deity guided by rage, to the essence of the ancient Earth landscape, manifesting into forests that sway without wind. As life on Earth evolved, so did demons; eventually, they began to mimick the emotions, desires, and forms of those which comprise their being. The impact of demons on the physical realm were minute before they made contact with humans, who soon learned to invoke and corrupt the previously benign anomalies.
Interactions with the mortal realm are possible if a demon is summoned by a human, or the demon latches onto a compromised vessel. (Apparitions are an exception, existing simultaneously within the physical and demonic dimensions.) For an organism to be possessed by a demon without interference from a human is very rare, not just because of the difficulty involved, but because uncorrupted demons have little incentive to do so. If a demon is summoned, it will appear in its "true form," which tends to be an approximation of whichever life forms the individual demon can conceptualize. This form is always unstable and will dissolve in time, and a flesh sacrifice is necessary for its formation.
While immortal, demons may be banished, effectively "resetting" their development and dispelling them into wisps of life energy. Studies from the Bahutha theorize that soul wisps must "clump together" in the ethereal plane to form demons in the first place. In this case, ghosts can be considered to be demons that have yet to amalgamate.
Demons' abilities are just as enigmatic as the plane of existence they occupy. They are most commonly summoned by humans to perform miracles such as necromancy or wish-granting. Mud Beasts are the best understood, as they are the only type of demon with the ability to communicate with humans. Given that they have acquired the ability to sap power from flesh sacrifices and human emotions, Mud Beasts are also the most effective at manipulating the physical world. The abilities of a demon depend on their origin and level of corruption, which is reflected in their classification. All demons leech energy from the physical world and implement it into their being.
Demons which are formed from the life force of flora become Apparitions, while those which are derived from animal souls are Lux. Lux who manage to make deals with humans or are manifested against their will are corrupted into psychic Mud Beasts, becoming extremely powerful as a result, but consumed by madness and desire.
Humans who are possessed by a Mud Beast are known as Parties, while animals that are possessed by Lux end up as cryptids or witches' familiars. Hollows are Bahut people who are augmented with the powers of a Mud Beast. Fairies were created when Mud Beasts and humans copulated during the dawn of civilization.
In areas where the barrier between the physical and demonic realms have been worn down- such as ancient Bahut worship halls- the environment of the demons' plane of existence can be observed. Fleshy growths seep into the halls and cover the surrounding architecture, implying that energy is not the only leftover from life that ends up manifesting into this alternate dimension.