The first Eidolons were part of a successful project by an Arcanist named Four Crystal Mountain Hawk, 35 years ago. A member of the Skull Conclave, Four Crystal’s goal was the grafting of specially treated Abyssal tissue for the purposes of physical enhancement and the granting of magical prowess to those who are otherwise without it. Their experiments were 15 years in the making before they yielded something that was beyond failure.

Despite the 90% death rate and the rumored escape of a few subjects (including his own son), it was deemed a success to the point that Four Crystal was granted the opportunity to form his own Priory. The process has been refined and improved to the point that subject death is highly minimized when performed using a Biomancer Hatchery (less than 5%) -- many are the individuals that undergo this painful and life-altering process in service of the Templars.

Incidentally, parts and pieces of this magical rite have spread across the World Beyond the Fall. The Scavvers are said to have their own version of it as do the Skull Conclave and other organizations. Even the Illustrados have had some limited success with this dangerous procedure, though their own experiments on the matter have been promptly shut down by the Magistrados.

The introduction of an eldritch life-form to the human physiology rarely results in a happy marriage of the two beings. In fact, it usually ends with the destruction of the human or their unwilling infestation.

Magical experimentation and a powerful will have melded to create the Eidolon, whose alien organs and functions work more readily with their human hosts than their previous forebears. In addition to the hump that marks the individuals with this Stigmata, it is believed that not all the organs of the Eidolonic Spore are in our reality, tethered instead in an alternate dimension.

An individual with this Stigmata is sustained by their Eidolonic Spore, reducing their eating, drinking and breathing requirements. It is believed that it takes an Eidolon over one month before they die from starvation -- a horrifying process involving the Symbiote’s voracious appetite if it is not “fed”.

On the other hand, those with the Eidolonic Stigmata are not currently projected to have an exceptionally long natural lifespan. Many Eidolons died in the War of Embers but scholars studying the organs of current Sporelings believe that their rate of degeneration is greater than a normal human’s, barring their own Bloodline Stigmata’s interference in that regard. That said, work on Spore treatment and progression may yield improvements in this aspect and in others if the Skull Conclave’s plans continue on their path.

As an Imbued Stigmata, Eidolons cannot pass on their Graft to their children. In fact, Eidolons cannot get pregnant or impregnate someone else -- it is believed that the Stigmata is too jealous to allow children to flourish within an implanted body.

The exception to this is the Dryadic and Mycetic Eidolon -- some of these individuals are able to implant an Eidolonic spore into a willing ally.

The origin of the Eidolons are steeped in machinations of sorcery and the eldritch, thus all Sporelings are able to become Arcanists or have access to the Etheric Arcana skill. Most are influenced by the choices that they made and the powers that they wield -- the alien spore within them allows them to test their wills against reality and thus against their own fates.

Most are Diabolists, with the same spore empowering them even as it agonizes them. Others have taken to Animancy, gaining guidance through their extrinsic faith.

These are simple role-play notes that you may choose to add to your character that reflect the influence of the Eidolonic Stigmata upon their personality. You may pick any or none of them for your character.

— Distracted: The Eidolonic Stigmata not only persists in the visible flesh but also in the invisible realm of the mind. Eidolons often report hearing whispers in their quiet moments and are sometimes plagued by nightmares. This means that Eidolons are not always at the task at hand -- this is more apparent during their downtime rather than “on the field”. Whispering to a distracted Eidolon is a bad way of getting their attention as many have learned to ignore such quiet sounds.

— Motivated: For many, the whispers within their mind and the crawling inside their flesh is an irritating stimuli to be subjected to or a horrible reminder of their Graft. While more than a few Eidolons simply manifest this in grumpy irritability, others dive into work or play with great gusto -- anything to distract from the goings-on within their flesh.

— Righteous: Most Eidolonic implantation is mired in the religious tenets of the Temple. Therefore, these Eidolons are obsessed with order and the maintenance of it. They will mend broken things and wounded individuals. These individuals will right wrongs and heal the sick, trying to bring back a semblance of order and/or nature to this ruined world. They fight an uphill battle, to be sure -- but they believe that it is a battle worth fighting for:

There are currently five different types of Eidolons, although some Eidolons possess the powers and qualities of two Subtypes instead of just one via the Unique Subtype Milestone.

— Cnidarian Subtype (Dusa): Cndarian Eidolons bear some similarities to the terrestrial jellyfish and coral, particularly their colorful and shimmering hues. They are contemplative and meditative, tending toward observation over action.

— Dryadic Subtype (Dryad): Dryadic Eidolons are marked by the haunting, yet beautiful flowers that extend from their form. Despite their relatively poor senses, they tend to be focused on aesthetics as well, seeking to create or display things of beauty and form. Some rebel against this and embrace the grim and macabre instead.

— Kulexic Subtype (Louse): Kulexic Eidolons reflect the quick gnat and the bloodsucking mosquito. They are quick on their feet and with their hands, marked by chitinous plates and black fur. Some have described these Eidolons as frenetic or even manic, with the occasional periods of languorous torpor.

— Mycetic Subtype (Moldcap): The first known type of Eidolon resembles the mycotic and fungal lifeforms of Earth. They tend to be blunt and straightforward but also willing to delve into dark and dangerous places. The Spore pushes their aesthetics toward the bloody, the grotesque and the macabre.

— Umbral Subtype (Umbrals): Umbral Eidolons are likened to the octopi and the slugs of Earth’s fauna. They are known to be furtive and stealthy, preferring to remain out of most folk’s attention but their own strength and prowess easily make them known to strangers.