Demon Possession

Demon Possession (悪魔憑き) is a strange disease and magic curse cast by the demon king, Diablos, that affects people born with the demon Diablos' blood in their veins due to being the descendants of the Three Heroes that defeated him. It is a sudden event where a woman's body suddenly begins to rot until it is not recognizable as a human being anymore and dies one day.

However, these symptoms are revealed to be a form of magical overload that manifests in the female descendant of the Three Heroes, leading to the afflicted suffering physical degeneration as it progresses, thus leaving the afflicted a hunk of flesh rotting, until it dies.

Overview
Demon Possession is a state in which the excessive magical power that has been inherited by the female descendants of the Three Heroes of each tribe of Elves, Beastkins, and Humans who subjugated the demon Diablos, which manifests in the blood of the heroes' descendants to varying degrees depending on the lifespan of the race which is too powerful and has gone out of control.

At a certain stage depending upon the species' lifespan, the cells will begin to take over a female descendant's body and eventually transform them into a misshapen and rotten chunks of meat for the most part. The rate of occurrence decreases as the blood of the hero generation fades due to the change of generation, which is rate on the elves, follow the beastkins, and finally humans.

In the final stages, when the curse strongly transmutes the body of the afflicted girl, she will no longer be able to be aware of what is happening in her surroundings while she continues to mutate and slowly begins to produce, already for those stages, it is possible that she no longer knows. need to eat or drink anything, since the curse itself keeps the afflicted tormented, but does not let her die, nor does it allow her to commit suicide, not being conscious in that state, when the semifinal stages are reached. A clear example of this is Alpha, since when she was captured by the bandits in her transmutation stage, she has not been conscious of anything since then, barely remembering that she was exiled from her homeland, nor did she know what Cid kageno did to her. while experimenting with it.

Humans who have undergone many generational changes have a lower occurrence rate of demonic possession, while Elves who have fewer generational changes, have a higher occurrence rate. The greatest percentage of those who manifest are elves, due to their long lifespan they are fewer generations removed from the time Diablos was slain.

This curse as such mainly affects women, while in the case of men it is null, since these are not compatible with the blood of the devil, they would die, as seen in the experiments carried out by the Cult of Devils. Even if men were born in the lineages of the 3 Heroines, even if they inherited their blood, the blood of the demon would remain, completely inactive in an inaccessible way in their bodies, without harming them in their lives, but in the girls of the men descendants of the heroines, had with their wives that are not linked with the blood of the devil, if they contracted the curse of Diablos.

Background
After being killed by the legendary Three Heroes, Diablos placed a curse on them so that they and their descendants would suffer painful deaths. Without exception, the affected patients collapse into ugly masses of flesh, and are hated and abandoned by their families, also cast out by the society.

Due to the sufferers being a descendant of the Three Heroes, The Church then tell the public to hand over the symptoms of possession, even takes over for a fee and order these individuals to be executed under the guise of purification, in order to free them from suffering by stating that those who are possessed by demons are monsters that can infect others who are close to them. They claim that they are protecting the common folk, but not before as they actually trying to disposes of it and use them through human experiments for their research experiments.

Symptoms True Identity & Cult's Propaganda
Demon Possession's true title is the "Curse of Diablos" (ディアボロスの呪い), which only manifests and afflicts in females itself because the heroes who fought Diablos were females. Its true identity is that a person who was implanted with Diablos Cells in an experiment by the Cult of Diablos in the past was unable to adapt to the cells and had a rejection reaction, causing the cells to go out of control.

Diablos cells are controlled by magic, so if the person himself has enough magic power control ability, or if someone else controls it from the outside, it will adapt to the cells and the body will not collapse. The Three Heroes were also implanted in the same way and as a result of inheriting Diablos cells when they gave birth to their offspring, people with Diablos cells spread and the phenomenon of demonic possession began to be seen all over the world.

In order to hide the existence of the experiment, the Cult of Diablos, with its roots deep in the Church, change the true name into "Demon Possession" and treats it as a "disease" that should be avoided, and prioritizes hunting and executing those who have demon possession until disposes of it at the church to prevent the truth from being exposed. The world has been led to believe the Cult's propaganda, as the reality it's that the Three Heroes were each implanted with cells taken from Diablos by the Cult.

For this reason, it has become a business to bring demonic possessed patients to the church. The cause is that a large amount of magical power accumulated in the body went out of control. Therefore, it is possible that these patients have great power, and the Cult calls these individuals as a "Compatible" (適合者) and strives to secure them.

The reason why the Cult tried to find any individuals who which already had a possessed symptoms was because the occurrence rate had decreased with the change of generations, which made the amount of Diablos cells is much decrease considerably since they were becoming the main ingredients for to creating the Tears of Diablos.

Curing Demon Possession
While demonic possession can be cured with magic, it is said that the Cult of Diablos tried in the past but was unable to create a cure, as the curse was very powerful comparable to a demon king, assuming there wasn't a cure for it, which consider as a long lost technique.

They could only create a magical method of slowing it down, to be able to continue studying and experimenting with the possessed girls, either to turn them into living weapons, or to continue extracting blood from them, as long as it is useful to them. A clear example of this is the Viscount Grease's daughter, Millia, who fell prey to the cult, and instead of dying from demon possession, she became her deformed being but half aware of this, through the experiments that were carried out on her. they did to keep her alive as long as possible, although she was still partly deformed and mutated, and at the end, losing control of herself, becoming a very large monster with high regeneration power, receiving a dose of liquid, injected by the scientist who kept her in her cells next to Alexia Midgar.

That is until Cid Kagenō in his young age manages to discovers one of these people undergoing the effects of Demon Possession and doing magic experiment by trains his ability to use magic through the individual's enormous amount of magic power seeping from it. In consequence, Cid gained an enormous amount of magical power and control. When Cid completely suppressed the magical deviation that was getting out of control inside the already decaying possessed body, he accidentally managed to heal himself Alpha and established a cure to return it to its original form. A side effect is that the afflicted's magical power will increase a bit, after being healed of their curse, but only by 5-10% just once.

All of the Seven Shadows of Shadow Garden had Demon Possession until Cid cured them. Cid also curing his sister from demonic possession when she turned 14 years old, thinking it an error in her mana flow.

Before or after Seven Shadows leave their lord, Cid, Alpha and Epsilon are able to cure the people who had the Demon Possession beside Cid and they are able to recover any individual who have a possessed symptoms, also subsequently recruited them into the Shadow Garden organization when the "Seven Shadows" began their membership expansion. After that, it was used by Shadow Garden on manifesters, and they used the cure method to increase the number of members along with treatment. Most of the Shadow Garden members below Seven Shadows have experienced the disease, and the fact that they saved them from that situation is the source of their loyalty to the organization.

Eta's Theory Research Relation on the Vampire Progenitor's blood
Eta was conducting an research about the Demon Possession on the Vampire Progenitor's blood, to which she acquire a certain hypothesis theory. Over the course of her research, Eta discover that there’s a possibility that the blood of the possessed and the blood of the Progenitors share the same origin and that the two merely diverged as they were inherited from parent to child.

For certain result, Beta will go to the Crimson Tower at the Lawless City, where the Vampire Progenitors reside and take a blood sample from a Progenitor, so Eta could check for her lab progress. Also, her job is to continue surveying the materials in the library and collecting anything which is important to further the theory research.

After Beta has already secured the Blood Queen's blood and seals it in a vial, he takes them to the lab where Eta would analyze it. At the time of the conclusion of the research progress, it was shown that Eta's theory could be valid. With the vampiric power that could come in handy along with proper training, Shadow Garden is able to master the Progenitors' technique.

However, it is not yet 100% confirmed, since according to the previous words said by Mary, this is blasphemy against the queen of vampires, since she and her family are sure that she has no relationship to nothing. This is reaffirmed, when Aurora told Claire in her mind space, that the curse she now has caused by the vampire's blood is very different from the demonic possession she was cured of in her childhood.

Trivia

 * Cid Kagenō figured out that Demon Possession is symptoms that afflicts the individual with high mana are at risk of losing control of it, which becomes a mutation state.
 * It was then Cid are able to know how to reverse the transformation by experimenting on the mutated Alpha, which not only restored Alpha but also granted her control over her increased mana.
 * During the experiments, Cid also figured out how to replicate the effects in himself, increasing his own power in the process.
 * Every member of Shadow Garden is a girl who succumbed to the "curse", which was subsequently healed and all of them from the descendants of the Three Heroes have at least decent magical abilities.
 * During membership recruitment, Eta created a device known as Locator of Possess, that which could track anyone with possession symptoms who would later be cured and recruited by Shadow Garden.
 * Although Alpha and Epsilon are the only ones so far that can heal the Curse of Diablos, apart from their lord Cid, apparently only their lord, can heal all kinds of afflictions and curses thrown from their enemies, like when he heal everyone which afflicted the Vampire's curse during the battle that Cid/Shadow had against Elizabeth at the red tower in the Lawless City.
 * In the past, Cid in his childhood, suffered from something similar to what those possessed by the curse had, while experimenting with his magic, but instead of mutating, his body began to feel like it was going to explode strongly, but he managed to control his magic power in time.