Eidolon

"It may look like a person and talk like a person and maybe even bleed like a person, but it's a monster."

- Jace Wayland

An eidolon (plural: eidola or eidolons) is a race of shapeshifting daemon who can possess and transform into any human being.

Overview
In ancient Greek literature, an eidolon (εἴδωλον) is a spirit-image of a living or dead person; a shade or phantom look-alike of the human form.

The concept of Helen of Troy's eidolon was explored both by Homer and Euripides. However, where Homer uses the concept as a free-standing idea that gives Helen life after death, Euripides entangles it with the idea of kleos, one being the product of the other. Both Euripides and Stesichorus, in their respective works concerning the Trojan Horse, claim that Helen was never physically present in the city at all.

In Theosophy, the astral double or perispirit or kamarupa after death, before its disintegration, is identified with the eidolon.

Summary
The eidola, much like the majority of daemon, are the creations of the original demons who used them to wreak havoc in the mortal world, especially on Earth, and bring death and destruction upon mankind. They, in particular, were created by the original Belial to sow lies and mistrust into the hearts of men and to be harbinger of misfortune of whoever sees their faces.

After the original Belial was sealed within the Underworld with many other demons because of the Ouroboros Barrier, the Alpha Eidolon pledged allegiance to the Belial Clan of the 72 Pillars, true descendants of their creator, and thus, the true leaders of the eidolon daemon.

After the Alpha Eidolon was killed in the Great War, the heads of the Belial Clan became the leaders of the eidola, with the current lord being Baelor Belial.

Appearance
Normally, eidolon daemon in their human form are practically impossible to separate from regular human beings. However, due to them only "borrowing" the appearance of a pre-existing person, there will always be two versions of the same person who are similar from their personal preference to even their DNA, possibly even more if said person's appearance is taken by more than one eidolon.

In their true form, an eidolon daimon is greasy and slimy like a giant slug, with their body covered in gray pockmarks and a glowing "brain" can be seen floating inside the dark slime. On films and cameras, their eyes will be a glowing silver-gold color.

Characteristics
Eidola are born as slug-like creatures that are "more slime than slug", but eventually grow into a human form and later on, learn how to shapeshift their form to look like anyone they want. When exactly they learn is unknown, as some can instantly learn it from infancy, while others do not learn until their teenage years, adulthood, or even much later in their lives. As all eidola, excluding the Alpha Eidolon, are born from human mothers, they are born with human impulses and desires, and are not driven by an instinct like vampires and werewolves, and thus, all acts committed by them are purely their choice.

When an eidolon takes the shape of the person they choose, they shed their skin, teeth and nails. When they change into the person's physical appearance, they access the thoughts of the person they are mimicking. Some eidola are known to change their shape in a matter of seconds, while others require several hours. Some descended from the Alpha Eidolon have displayed the ability to seamlessly shift into whoever they want without shedding their skin. They can also take the forms of fictional characters or inhuman characteristics, such as vampire fangs or werewolf claws.

Despite this, not all eidola can perfectly take on the form of another human being, either as the result of their low amount of demonic power or their lack of experience and/or age. Because of this, these eidola would often be disguised as "generic humans" with unmemorable features, or members of a crowd, rather than impersonating specific individuals.

Some old and experienced eidola can also possess the bodies of human beings and take over their mind and actions with relative ease. To do so, they are required to be in their true form, which is their most defenseless state, before slipping into their intended host's body through different means, though the most common methods are through the ears, nostrils, or throat. In this form, they can be exorcised using the standard rituals and will leave their victim's body as a "dark wisp of smoke". Extremely powerful eidola are said to even be capable of possessing electronics or automatons, though those who can do so are extremely rare to find.

While some eidola appear to simply cycle through appearances and never settle on one particular permanent appearance, other eidola appear to have a preferred appearance they use when they are not impersonating another person. Often, this chosen form is what they would have looked like had they been a normal human born between their mother and the form their eidola father took, though some forms can also simply be the one they like.

Abilities
TBA

Weaknesses

 * Physical Damage: Like most supernatural creatures, eidola 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. They can also be easily killed by mundane weapons and methods alike if they are in their true form, in which they have little to no way to defend themselves.
 * Retinal Flare: Eidola can be identified by a silver-gold retinal flare that shows when they are filmed or when light rays across their eyes.
 * Animals (Dog): Like most daemon, their presence can be identified by certain animals. In the case of eidolon daemon, dogs can identify them regardless of what forms they take, and the sight of them can turn even the most harmless dogs into deadly violent beasts.
 * Dog Blood: They can be weakened and defeated if they are covered in and/or consumed dog blood. If they are covered by it, their human form will disappear and they will be forced to transform back into their true form, and if consumed, they stomach will begin to heat up and then incinerate itself from inside out.
 * Light Element: As daemon, eidola are the natural enemies of the Light element. They are vulnerable against natural sunlight, which weakened them 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 them.
 * Holy Attribute: As demonic creatures, the holy attribute is the bane of all daemon like the eidola, regardless of their strength. Religious symbols, scriptures, and prayers are extremely effective when defending oneself against one of them, and items imbued with the holy attribute are considered to be the most effective weapons to use when fighting against them.
 * Hallowed Ground: Eidola are incapable of entering hallowed grounds, such as churches, synagogues, mosques or other religious places without hurting themselves by every second.
 * Holy Weapons: Eidola 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).
 * Celestial Weapons: Weapons made out of sacred metals can be used against the majority of supernatural beings, with daemon like eidola being no exceptions.
 * 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.

Trivia

 * Their name means "image", "idol", "double", "apparition", "phantom" or "ghost".
 * They mainly live in the Belial territory in the Netherworld and in the Circle of Sloth in the Underworld.
 * Some eidola might even work for pagan gods in exchange for human blood and flesh.
 * In the Second Giant War, Gaia is said to employed a legion of eidola in her service.
 * In the mortal world, they often make their lairs in dark and damp places like sewers.
 * They are native to Mediterranean regions, especially in the countries of Greece and Egypt.
 * Their skin can secrate a type of slime-like sweat which can transform into any clothing they want.
 * They can only breed with human women and the offspring is almost always another eidolon.
 * Offspring between eidola and those with latent magical power will usually born warlocks.
 * It is unknown if an eidolon can breed with a human man, though it's implied to be possible.
 * An eidolon named Charles Douglas had a human twin brother, suggesting that in such cases, not all children will be born eidola or warlocks, and some might even be born humans.
 * Unlike other demonic creatures, they are incapable of noticing others of their own kind.
 * Despite popular belief, they are neither ghosts or undeads.
 * While they are known as "skin-walkers", they don't seem to have any similarity with the monster of the same name from Najavo mythology, other than the shared power of shapeshifting.