Devil

"It's over now, Lord of House Beelzebub. The reign of the Old Satans has come to a close. This is a necessary change to create a newer and better world for our kind. And sadly, in this new world, those who are stuck in their old ways such as you, cannot be allowed to live."

- Sirzechs Lucifer

Devils were the creations and descendants of the original demons from the Underworld, and the main inhabitants of the Netherworld. They, alongside the angels and fallen angels, formed the Three Factions of the Abrahamic pantheon.

Summary
Devils are beings created by the demons to serve as heirs, concubines, servants, and warriors within their armies in their conflict against the angels of Heaven and the fallen angels of Purgatory. They are native to the Netherworld, the first and highest level of the Underworld.

The first devil is Lilith, who was created by Lucifer shortly after his imprisonment and acts as the original template for all devils and cardinal devils created after her. She took on his title of Lucifer and started the royal Lucifer Clan and ruled over the devils of the Netherworld for hundreds of eons. Many royal and noble houses began to appear later on, following in the Lucifers' footsteps.

In the Great War, thousands of millions of devils were created by the demons to serve as a military force against the armies of Heaven and Purgatory, to satisfy the Emperors of Hell's ambition for total domination of the entirety of Creation. However, after the Ouroboros Barrier was created by the Four Great Seraphs' sacrificed divinity, the majority of the demons' armies were destroyed as their territory was now confined to a single realm disconnected from the Underworld, floating around aimlessly until the remaining demons got sick of it and attached it to the divine world through the Realm of the Dead.

After the deaths of the original Four Great Satans - Lucifer (Lilith), Asmodeus, Beelzebub, and Leviathan, the devils began to settle down and tried to establish their former order, especially after most demons had decided to retire and spend their time everywhere but in the Netherworld leading their servants and descendants.

The eldest children of the Four Great Satans then took over as leaders of the devils because of this, though their reputation toward their new subjects began to turn for the worst when they made their desire to continue the Great War clear, which would undoubtedly make the remaining devils went extinct.

Because of the disagreements between the new Satans and the 72 Pillars, whose power was becoming greater and were now firmly established as the nobility of the Netherworld, with some even taking over their creator's reputation as the "true" demonic entities mentioned in biblical records, a revolution was started, which then grew bigger and bigger in size until it became the Devil Civil War.

The civil war soon ended in the rebels' favor, as the second-generation Four Great Satans were overthrown by the Anti-Satan Faction's leaders, who were then appointed the leaders of the devils' new government because of their leadership, power and their accomplishments in the civil war. The remnants of the Old Satan Faction then fled the Netherworld and formed the terrorist group known as the True Satan Faction, which later joined and became the largest faction of the Khaos Brigade.

After the formation of the new devil government, Ajuka Beelzebub developed the Evil Pieces system to help replenish the decreased armies and population of the devils, eventually creating the Rating Games.

Appearance
Most devils look the same as humans, albeit with a pair of bat-like wings that they are capable of retracting back into their back as if they have disappeared entirely, though there are several noble houses whose wings appear much different from their fellow devils, resembling that of different mythical avians.

Some pureblood devils have multiple pairs of bat-like wings, however, unlike angels and fallen angels who can gain multiple wings over time as their power grows, this is limited to those who are descended from the original Satans from within at least three generations, i.e. their children, grandchildren, and great-grandchildren. Cardinal devils also possess this trait, though theirs are limited to only three pairs of wings.

There are some devils who appear to have the characteristics of creatures and monsters, such as the Vepar Clan being merling-like devils, or the Forneus Clan whose members resemble anthropomorphic sea monsters. Zephyrdor Glasya-Labolas has pointed elf-like ears and Roygun Belphegor has two horns on her head. These devils are often the children and/or descendants from interspecies marriage between devils and another species, typically daemon due to their shared nature as demonic creatures.

Reincarnated devils, being formerly of another species entirely before their reincarnation, can come in a variety of shapes and sizes, such as the case with Tannin (a former dragon), Enku (a qilin), or Koneko Toujou (a nekomata),

Characteristics
Despite their demonic origins, most studies have shown that devils aren't much different from regular humans. Their biggest differences between the two species seem to be the devils' much looser and carefree lifestyle than humans, preferring to live based on their own desire first and foremost, and having no problems indulging in their own sins than to try and contain it. They also have a much looser morality than humans, having not much of a problem with what ordinary humans would consider worrisome or problematic.

They don't have the exact same traditional values when it comes to marriage like most humans, and are known for their hedonism. While there are many couples of monogamous devils, the majority of them still practice polygamy, with many of the nobility even having multiple harems of different sexes and oritentations of their own, in addition to having multiple lovers outisde of their pre-established relationship. However, for pureblood devils, it is often required for them to produce at least two heirs for the family name before they are allowed to have a lover/partner of the same gender.

Devils aren't too afraid of what are traditionally taboo subjects. They, or at least only among the nobility, practice incestuous marriages and inbreeding, marrying family members together to ensure their bloodline pure, despite the numerous genetic disorders that could potentially befallen on their offspring, if they ever have any. However, as of 20XX, due to new laws established by the Four Great Satans, incest have been deemed illegal all across the Netherworld and all of their demonic colonies.

Most of them value strength and blood purity above everything else, though the first is predominant in nearly all devils while the latter is mainly valued by the pureblood and the nobility. Because of this, many regions and sub-cultures within the Netherworld seem to revolve around the strongest warriors and fighters, and often look down upon the non-combatants, such as scholars or entertainers.

They aren't afraid of death and destruction and seem to recover from their trauma much quicker than most sentient species, and while some devils still suffer from mental disorders such as PTSD, theirs don't seem to be permanent and can be easily dealt with provided enough psychiatric guidance. This is because devils were originally created as the demons' soldiers and were thus genetically programmed to be extremely resistant to most forms of mental and/or psychiatric damage.

Abilities
TBA

Weaknesses

 * Physical Damage: Like most supernatural creatures, devils can still be killed through mundane means if they have either received serious or immense physical damage or received fatal wounds that aren't healed in time.
 * Light Element: As demonic creatures, devils are the natural enemies of the Light element. They are vulnerable against natural sunlight, which drains them of their stamina and demonic energy if they are exposed to it for an extended amount of time. Intense light, such as the one generated through Light Magic or used in the light constructs of angels and fallen angels, are extremely deadly weapons against devils.
 * Holy Attribute: As demonic creatures, the holy attribute is the bane of all devils, regardless of their power and rankings. Religious symbols, scriptures, and prayers are extremely effective when defending oneself against a devil opponent, and items imbued with the holy attribute such as holy water or consecrated oil are considered the most effective weapons to use when fighting devils. However, depending on the amount of demonic power a devil possesses, the effects of the holy attribute has upon them may differ: The higher one's demonic power, the less effective the holy attribute will be upon them, and vice versa.
 * Hallowed Ground: Devils are incapable of entering hallowed grounds, such as churches, synagogues, mosques or other religious places without hurting themselves by every second. If a devil accidentally ingests dirt taken from these places, they will be poisoned, weakened and their stomach will slowly melt away and their innards falling out.
 * Holy Weapons: Devils are easily wounded by weapons bearing the holy attribute, like holy swords or Sacred Gears with divine properties, such as Blade Blacksmith or Twilight Healing (Asia's the single exception).
 * Heavenly Weapons: Devils can be easily killed with weapons of a heavenly or divine nature.
 * Celestial Weapons: Weapons made out of sacred metals can be used against the majority of supernatural beings, devils included.
 * Primordial Regalia: Weapons and artifacts that belong to the primordial entities can be used to permanently and absolutely destroy every and any being in existence save for other primordial entities, erasing their existence completely so that they can never be reborn or resurrected without God's involvement.

Types of Devils

 * Cardinal Devils ( 枢機卿の悪魔, Sūkikyō no Akuma ): The original devils created by the demons and progenitors of the pureblood devils. They are the secret rulers of the Netherworld through manipulating their descendants and noble houses as parts of the Great King Faction. Aside from the first members of the Satan houses, all cardinal devils are created using the original devil Lilith as the template.
 * Pureblood Devils ( 純血悪魔, Junketsu Akuma ): The natural-born devils who are from the noble houses of the Netherworld, such as the 72 Pillars and the Extra Demons. The majority of them are aristocrats and each house they are from has its own domain, as well as a hereditary power that is specific to their clan, inheriting from their cardinal devil ancestors who received it from their creator demon. The majority of them practice inbreeding in order to keep their bloodline pure and their hereditary power not get passed to other houses.
 * Reincarnated Devils ( 転生悪魔, Tensei Akuma ): The devils created by the High-class devils by using Evil Pieces to reincarnate non-celestial beings into one of them. They serve the High-class devil who reincarnated them and is the King in the peerage.
 * Stray Devils ( はぐれ悪魔, Hagure Akuma ): The reincarnated devil who killed their pureblood masters and was corrupted by their own demonic power as a side-effect of the broken bond between them and their King. The devil government takes this situation very seriously and any stray devil that appears will be immediately killed.
 * Mixed-Heritage Devils ( 混合遺産悪魔, Kongō Isan Akuma ): The devils born between either a pureblood devil and a reincarnated devil, or between two reincarnated devils. They couldn't be considered half-devils due to both of their parents being devils, but not pureblood devils as well because of their diluted bloodline, not to mention the fact most High-class devils look down upon reincarnated devils. Because of this, noble houses with only mixed-heritage devils as members are considered "extinct" by the higher-classes, as shown with the Marchosias Clan and the Andrealphus Clan.
 * Half-Devils ( 半悪魔, Han Akuma ): The devils born from the interbreeding of devils and other species, most notably humans. Due to the pureblood devils' pride and obsession with blood purity, the half-devil descendants of pureblood devil houses are often scorned and looked down upon. However, due to their mixed blood, they gain the abilities of both species, as half-devils with human heritage can manifest Sacred Gears.
 * Super Devils : The devils who are considered irregular beings due to possessing abilities surpassing the realm of devils, thus making others wonder whether or not they can just be considered devils. Some of the known Super Devils are the current Four Great Satans, the second-generation Satans, Lord Baelor Belial of the Belial Clan, and the two Heavenly Dragon Emperors: Vali Lucifer and Issei Hyoudou. The artificial devils created by Pralaya using Lilith's flesh can also be considered Super Devils, even though their existence haven't been certified by the Netherworld government.

Population
Originally, the devils possess the largest population among the Three Factions, with their number ranging in the hundred-millions of billions, created to serve as the servants, concubines, citizens, and warriors for the demons who ruled over all demonic creatures at the highest top of the infernal hierarchy. However, everything changed when the Great War came and billions of devils' corpses littered the battleground to the point where they formed entire mountain ranges.

During the Devil Civil War, the devils' population was halved again when 39 houses of the 72 Pillars were killed by the Belial Clan's army under the order of their heir, Baelor Belial, and killed off over 60% of the pureblood devil population. In addition, due to the miasma rising from the rotting corpses of slain devils, many female devils were rendered sterile as the result.

Despite their exceptionally long lifespans, they cannot reproduce easily as the rate of pregnancy among devils is very low, in addition to the natural miasma in the Netherworld which can easily induce infertility and miscarriages. Because of this, sometimes it requires the would-be-parents centuries to produce a single living child, and having more than 2 children is considered rare among devils.

Due to the excessive loss of population, the Evil Pieces system was created to replenish the number of devils by reincarnating other species into devils, with humans being the most common choice among the species.

Ranking
The devils use a hierarchical system that is split into four different ranks. The ranking here refers to the hereditary title given to devils based on their classes and clans and reflect on strength. They are:

There are three different ways to raise one's ranking:

Middle-Class Promotion Test
Once a Low-class devil has earned the right to raise their ranking, they must first be tested before actually gaining the position. And while not everyone succeeds in these tests, they can try as many times as they choose, as the permissions do not normally expire.

The Middle-class promotion test has three parts that are modeled after the tests in the mortal world since a majority of the devils who take the promotion tests are reincarnated devils, whose majority are former humans.
 * The first part is a written report that addresses the theme of aim and ambitions.
 * The second part is a written test involving the history and government of the Netherworld.
 * The third is a practical test where an individual faces off against another participant from the test in a one-on-one fight.

High-Class Promotion Ceremony
When a devil goes to their High-class promotion ceremony at the ceremonial hall, and that devil and those with them are escorted in limousines under strict guard, several security cars surround them and treat them like a VIP. They will be taken to a temple where they will go under a ritualistic cleansing of all miasma on their body and be bathed in scented oils.

At the ceremony, the promoted devil stands in front of an altar with their master by their side and the Satan in charge reads what is written on their certificate which states the reasons for their promotion. The Satan then proclaims them as a High-class devil and they kneel down on one knee to receive their certificate with words of acceptance. They display their certificate to the audience to which they applaud. Next comes the crowning ritual. For the reincarnated devil, they face their master at the altar, get down on one knee, and their master places a crown upon their head with another round of applause.

For the final part, the Satan stands on the altar once again and summons a giant block of Agreas crystal used to create the Evil Pieces. The promoted devil envelopes their hand in their demonic power and touches the monument, making the crystal block shine crimson before returning to normal. Their registration as a King is now complete and they are handed a small box containing their Evil Pieces to make their own peerage. As such, the ritual is done with the most crucial part of the ceremony.

What comes after this is the words of congratulation from the guest which is read by the host of the ceremony and a celebratory banquet, in which the words of congratulation from the guest which is read by the host of the ceremony.

Four Great Satans
Four Great Satans ( 四大魔王, Yondai Maō ) are the four leaders of the devils and the Netherworld. The current Satans are not the actual ones but were chosen to replace the original Satans who had died in the Great War and are each named after one of the four original Satans: Lucifer, Beelzebub, Asmodeus, and Leviathan. Therefore, these names are not personal names, but are more like managerial positions.

72 Pillars
72 Pillars ( 七十二柱, Nanajūni Hashira ) are the list of the 72 noble families of pureblood devils who act as the aristocracy of the Netherworld. Each clan possessed dozens of armies under them, but after the Great War, every clan lost the majority of their armies and over half of the families from the 72 Pillars even faced extinction, with only 33 families of pureblood devils remaining.

Extra Demons
Extra Demons are the houses of top-class devils who are not a part of the 72 Pillars. Currently, most of the Extra Demons have excluded themselves from the current devil society, not wanting to involve themselves with the current devil government. Devils from the Extra Demons who involve themselves with the current devil government and society will have to break all ties with their families. Many of the families of the Extra Demons are once vassal houses of the Satan Clans.

Lilith's Children
Lilith's Children, also known as Unknown Devils, refers to the group of artificial Super Devils created by Pralaya from the flesh of Lilith using the souls the demons who died and current sleeping within the Empty as the templates. It is unknown why they were created, though Uriel had amusingly said it was because "... [Pralaya]'s like that sometimes".

Anti-Satan Faction
Anti-Satan Faction is a group led by Sirzechs Gremory, Ajuka Astaroth, Serafall Sitri, and Falbium Glasya-Labolas whose mission is to overthrow the second-generation Satans and stop their plans to reignite the Great War, which would undoubtedly lead to the extinction of the devil-kind. Their rebellion ended in their victory and the leaders was crowned the new Satans, leaders of the Netherworld and of all devils.

Old Satan Faction
Old Satan Faction ( 旧魔王派, Kyūmaō-ha ) was a group compromised of pureblood devils who fanatically supported the world domination desire of the original Four Great Satans and their successors, the second-generation Satans. They were defeated by the Anti-Satan Faction and remnants of the group later resurrected as the True Satan Faction, the largest faction within the Khaos Brigade.

Trivia

 * A devil's maximum lifespan is estimated to roughly be around 8,000 - 10,000 years.
 * Anyone with devil heritage can advance in ranks, even half-devils such as Vali Lucifer or Ingvild Leviathan.
 * A devil can train their familiar to hand out fliers instead of doing it manually, though most newly-reincarnated devils are made to personally hand out fliers to potential summoners as a tradition.
 * Even after reaching physical maturity, it is still possible for a devil's body to continue growing thanks to their demonic power.
 * Devils have particular illnesses that affect their species.
 * The Devil Fever gives them the natural fever, much like the human one, in addition to them being unable to use their demonic powers and sixth sense. It is said to be caused when the patient's being tormented by anxiety.
 * The Sleep Disease which originated as a curse created by a member of the Belphegor Clan. It causes one to fall into a dead-like sleep and will cause the afflicted to grow weaker and soon die if they aren't hooked to a life-support machine. After the peace treaty between the Three Factions was signed, the disease can be permanently cured using water taken from the Garden of Eden.
 * It is considered something of a rite of passage for a young up-and-coming High-class devil to make a pact with a magician. They are warned to choose carefully when making such a pact, as if they choose the wrong magician, it will reflect poorly on them and their house.
 * Despite popular belief, consent and free will are considered the most valuable things in devil culture, and any act that takes away either one of this from someone else is heavily punished.