Light Eaters

Light Eater(暗い中空; raitoītā, lit. Dark hollows) is a term to describe a human/devil who obtained special abilities and powers by devouring any holy creature, mainly Angels and Fallen angels. lost in history, Light Eaters are growing more and more as the balance between the Three Factions and the human world becomes more thinner, as well as the boundaries between them and their powers becomes less noticeable. Because of this nature, they usually are the main force antagonizing Heroes, and thus being called Anti-heroes( ''反英雄; Han eiyū). ''Devils guilty of such crime, unless they're powerful enough, are purged from devil society and killed if ever found.

A special division, called Lilith's nest(リリスネスト; Ririsunesuto), was specially made to create new Light Eaters in the Miyama House, an underground facility that plans to purge all the supernatural creatures from earth. Strangely enough, only one subject among the experiments was a boy. Aside from it, all the other recent light Eaters are girls.

Summary
It is unknown the exact origin of the term or phenomenon, but it is hinted that it was during the great war between the three factions, in which Devils would eat their holy counterparts out of desperation or just sick sadistic desire. While some would die instantly due to sacred nature of their prey's flesh, others would suddenly show new powers and abilities in a short spam of time, like a new pair of wings, pseudo-imunity to holy objects, the ability to create light weapons and so on. The Light eaters were the pinnacle of the devil evolution, but when the conflict stopped, all of them were judged and executed for war crimes beyond repair. During the events of the Original Highschool DxD timeline, the existence of light eaters had completely vanished from history as an old shame and a war atrocity that should not ever be repeated. The second time such event was recorded was during the Great Apocalypse, when one of the most powerful devil soldiers and future Satan, Cohen Alastor, devoured a dying angelic ally out of desperation, gaining a fair shade of light immunity and an extra pair of wings, earning the nickname "The two-winged monster". The phenomenon would quickly spread through the battlefield, and so several devils and humans alike would eat their dying angelic/fallen angelic allies to gain their abilities and continue with the war. However, such event caused an severe drawback, as only strong devils could withstand the overwhelming holy powers, while others would perish into dust. After the war, because of their indispensable aid during the war even with the dark origins of their newly-formed powers, Light-Eaters received amnesty, although some of them are still labeled as war monsters.

Enma Miyama, knowing about such phenomenon, created a special division in the Miyama House to help create human Light Eaters to serve as his soldiers in his rage against the devils and angels. Named Lilith's nest, Enma used a broken, tortured and shell-shocked Shemhazai and other fallen angels as a food source for the children and himself to enjoy, and soon all of them develop Light eaters abilities. Helena, a fallen-angel/human hybrid, would later become another light Eater after devouring a mad Azazel, showing that others can turn into Light Eaters even with their holy ancestry. It is unknown if angels can become Light Eaters as well.

Abilities
While the powers gained by devouring holy creatures may vary, all Light Eaters shares one trait: they have the name of their eaten fallen angel printed on their tongue, named Mark of sin(罪のマーク; Tsumi no māku), to remind them of the unspeakable atrocity they have commited. Devils LE gain a new pair of fleshy, pulsating distorted wings, while humans gain an "eerie, chilling aura" around themselves.It is noted that, to become a Light Eater, one must devoured an angel until their "existence are completely wiped out by your mouth", and simple lumps of flesh from them will not transform one into a Light Eater. One angel/Fallen angel, however, can be shared, cooked, seasoned and even mixed with other ingredients to one and others to become LE from it, the case of Shemhazai and other fallen angels held captive by the Miyama House.

One of the most common abilties gained from it is an pseudo-immunity against holy objects: demons can still sense and feel pain by them, but their no longer possess "devilish allergy" to other objects, such as crosses, rosarios, passages from the bible, holy water and so on. They'll also gain an extreme shades of luck, since the flesh they had consumed are holy, and humans will gain stronger auras to attract or intimidate other human beings. Sacred Gear users can unlock Balance Breaker faster by turning into Light Eaters, however, such unnatural evolution may cause the Sacred Gear to break, killing it's host. One can also turn into a Light Eater by devouring another Light Eater. Labeled as Sacred Retrievers(セイクリッドレトリーバー; Seikuriddoretorībā), they receive the power of the devoured Light Eater plus their own energy and a weaker version of light powers typical of angels and fallen angels. However, becoming one Sacred Retriever may backfire and kill the SR to-be. Those who can may be blessed by the heavens and use the eaten flesh of the previous Light Eater to revived the eaten angel, however, never in history such event have occured.

Human Light Eaters, like heroes as well, cannot be hypnotized or enchanted by either devils or angels magic because of their own version of Anti-Magic(抗魔法; Kō mahō).

Known Light Eaters

 * Cohen Lucifer(Devoured thousands of fallen angels and angels; gained anti-magic, new pair of wings)
 * Helena(Devoured Azazel; gained his intelligence and a new pair of wings)
 * Lilith's Nest(Devoured Shemhazai, his family and other fallen angels, gained holy and devil immunity.)
 * Enma Miyama(Devoured Kokabiel and rests of Shemhazai and his family; gained immense magical affinity; strength,durability and control over lesser humans and magical beasts.)
 * Reiji Miyama(devoured Shemhazai, his family and other fallen angels; gained holy and devil immunity and awakened Balance Breaker.)
 * "Ryuichi Himejima"(Devoured Baraqiel; gained Holy Lightning Ability, awakened Balance Breaker.)

Trivia

 * The light Eater concept was based on the cannibalistic nature of south-american tribal culture, in which would become stronger by devouring their enemies;
 * Cohen is the only known devil that feels proud of his Light eater status.
 * The concept of "devour" is only lightly adressed, since Cohen did not gained other abilities by eating chunks of angels/fallen angels, but the girls of the Miyama house did by eating the same fallen angel by pieces.
 * When they die, Light eater's souls are destroyed completely by the Heavens.