Umbrals

Using my thought-scribe spell, I will be recording the following event on the 2nd year of the founding of this great city:
On this auspicious occasion, I, Eleazar, First Mage of the First City, do declare my mastery of the dark to be complete. The gateway to the Whispering Dark will be opened momentarily by my hand and my hand alone. I've exorcised children. Swam the ocean depths. I've survived the hellscape of a dozen infested houses in the taming of this city. Through my leadership, a full third within the wall has been rendered habitable. Despite Arraesfel and his warnings, no fire was used and we have ascended to a place supreme and unassailable. Damn him and his arrogance.
...have to delete that from the record later.
By this authority, i declare the gate open.
The living shadows are the same across my experiences. Lazy, passive, not dangerous unless one is foolish enough to enter their domain. In opening this gate, I hope to gain a better understand for fighting this nuisance. Make no mistake, they are just a nuisance.
They... well I suppose it is called the Whispering Dark. A little noise, while unusual, hardly causes any concern. I'm sure there are thousands of things in a new plane to cause sounds. thousandswhisperingthousands
They run from a little light and a little hope. A simple enough thing for a magelittle of my stature.
magelittlehopestaturelittle
What? Arraesfel? This is not the time for your games. littlegamesstaturenotwhatwhatwhat
What knocked that over? Of course, they would be strong enough for that by now. Only need a bit of cleansing. notstrongabitlittlemageoveroverover
No, they don't... you can't...get back. Get back... theycan'tcan'tnodon'tcan'tnoyougetyounoyou

---The last page of First Mage Eleazar's Tome of Living Shadows

Basic Information

Genetics and Reproduction

No reproduction has ever been observed. It is theorized that a large enough umbral will splinter into smaller ones.

Growth Rate & Stages

Umbral grow based on the amount they are able to consume. On the ocean floor, they are sustained, but consistently, so they remain in what is referred to as their primary state.
In its primary state, an umbral is a very passive creature that is an incorporeal part of every day darkness. Only concerned with feeding itself from the shadow that surrounds it, it will harm nothing that comes near it, but will begin feeding from the shadow under the creature's skin. More often than not, this leads to a parasitic life of jumping from the host to the predator that eats it until they have left the lightless world behind.
Of course, the farther they are from constant darkness the more they must rely on their incorporeal nature to feed off something less literal. They begin to draw sustenance from negativity. Anger. Sadness. Loss. Despair. Each more rich than the last and, for those in humans, each sampled more and more freely as time goes on. Though passive in this state, the mere presence of an umbral naturally skews its host to a more cynical and pessimistic outlook.
As an umbral is allowed to glut itself, it will expand beyond the bound of its host body. Its slight autonomy from its host allows it to come to terms not just with what it enjoys feeding on, but the means to make more of it. Stark shadows in otherwise lighted rooms. Objects falling over without prompting. Slight, inexplicable touches on the host's skin or hair. All signal an umbral entering its "adolescence". Harm may even befall those around the host, up to and including death, but none will happen to the host directly.
Physical harm to the host signifies the umbral reaching its full maturity. It comes to terms with both the types of things it likes to feed upon and the way it can make more of those things from the world around it. What's more, if it has experimented successfully and not been exorcised by one of the few --in the Aether, at least -- who know how to deal with it, it will have grown exponentially and be capable of fully manifesting itself into rooms of even dim lighting dim lighting without its host.
The host is nothing more than an impediment to the umbral's burgeoning freed. Not even a sufficient battery source of food for an umbral of this side, the host will begin to endure a thousand small tortures before eventually encountering the roiling form of the erstwhile parasite. Killing the host allows the umbral to permeate the entirety of the its surroundings and begin driving away or, for those that acquired the taste for it, killing those others in the area. It will remain in the area for the rest of its life--thought to be a literal eternity as there is no biology to give out on this creature --and sustain itself off of the shadows it has created and any creature unfortunate enough to walk into its area of influence.
There is believed to be a fourth stage of development a sufficiently well-fed umbral can enter. This theoretical fourth stage would have the umbral evolve from an ambush predator to a more active hunter of suffering. The umbral in question would also develop the ability to communicate as there are no accounts of umbrals communicating more than telepathically and then only with their hosts. This theory is based off the accounts of the Whispering Dark and the way it behaves in no way like even the most powerful of the umbrals found in the Aether. It is thought that these fourth stage umbrals would accomplish this in one of three ways:
The first would be in continuation of what it has already done. It would attract more and more prey, mostly the overly curious and overly desperate, to milk for as much pain as it can before the last drop of sweet nectar that is death. This aggressive consumption is thought to have occurred on an Earth-like world already where an umbral powerful enough to consume even the stars expanded to for the Whispering Dark.
Another school of thought stated that a fourth-stage umbral could find away to lead other umbral to the same stage of development. This umbral would have realized that there existed no scarcity of darkness for a group to have to fight over. Super-naturally gifted, nigh undetectable, and feeding entirely off of the suffering of others, these umbral could take whoever they wanted and feast nightly.
The last method is touted mainly by the few demon-hunters that distinguish between umbral and demons. They state that there must be people who became aware of their umbral and reached an agreement with them. Rather than being consumed and ruined, these individuals would have a promised to feed the umbral well in lieu of having them exorcised or being eaten over time.
Luckily, no proof of any fourth-stage umbrals --other than perhaps the Whispering Dark itself --exists.

Ecology and Habitats

Like humans come into the Aether by walking through crossroads or other intersections of possibility, it is believed the umbrals come from a place known as the Whispering Dark. Few accounts exist of those that encountered the Whispering Dark and survived. All describe gateways to roiling voids of shadow. A millions voices whispering dark secrets and flagrant heresies to all who will hear. And, vicious questing tentacles shooting forth to pull those within reach to a death of a thousand agonies. It is never recorded how these portals are closed.
The umbral are thought to slip from this place to sympathetic areas in the Aether. Places entirely untouched by light or those absolutely abandoned seem to be ideal for them. As such, the ocean floor is thought to the be a swirling miasma of umbral feeding passively off of the deep shadow therein or attaching themselves to the marine life that swims by. When not able to find places of absolute dark, they will instead create for themselves an area of abandonment. These areas will be relatively untouched by light and undisturbed by those beings capable of bringing light against them.
Of course, spending their first while on the surface as parasites at the whims of their hosts, they may find themselves anywhere at anytime in the lighted world.

Dietary Needs and Habits

Umbral feed upon shadow and darkness. Being only semi-corporeal themselves, it does not matter whether this shadow is literal or of a more spiritual flavor. Those at the ocean floor seem to content themselves with the literal darkness of their lightless environment, but also mindlessly attach themselves to any creature that plumbs their depths. Hiding in the shadows that lie under a creature's skin and seeing through their hosts eyes, they will quickly find themselves starved for darkness. Invariably, they begin to feed off the negative emotions and experiences of their hosts.
When attached to a sentient creature, their mere presence will trigger their hosts toward more pessimistic and cynical outlooks. This, of course, allows the creature to feed more effectively. Over time, umbral begin to create small hardships for their hosts in dumb attempts to foster their food source culminating in a much more mature umbral manifesting entirely outside their host, killing them, and breaking free to spread themselves across their environment.
The umbral that manages to fully permeate its environment has graduated from being a dumb bottom feeder turned parasite to a mature ambush predator. As it has become a part of its environment, it will lure the curious or vulnerable to its abode --usually something like an abandoned house --in order to milk them for all the panic and agony they can give before eventually disposing of them for the sweet nectar of death. It is believed that it would be possible for a sufficiently strong umbral to graduate from a predator of stealth to a more a active hunter, but fortunately, no account of such a thing exists.

Additional Information

Domestication

The only being to have ever domesticated umbral is the Reaper Grim, though this is known to no one but himself. It is unknown how he managed to do this and entirely unrecorded. Those at his command have a much more stable appearance than their more wild brethren. They're also noteworthy for their near constant chattering as the Reaper uses them as much as a weapon of terror as to inflict harm. They obey him regardless of the command, but never without question or comment from a million voices in a million directions at once.

Uses, Products & Exploitation

The Reaper uses his umbral to attack opponents in combat and camouflage his approach. He is known for entering the homes of his prey surrounded by a moving tide of shadow that covers every exposed surface and speaks incessantly of a thousand damnations. At times, he will even open gateways into the Whispering Dark to abuse the amorphous geometry of the plane and move around just that much quicker. He is loath to do this though as they are not as well behaved in their own realm as they are under his command in the Aether.

Geographic Origin and Distribution

Majority live at the bottom of the ocean with a few scattered around chronically abandoned or hopeless areas on the surface. The second largest group can be found on in the eastern third of the City of Ancients, though no one in the city is aware of this yet.

Average Intelligence

Most Umbral do not exhibit much intelligence on their own. However, after acquiring a human host, they rapidly acquire knowledge and understanding of the world equivocal to their host's despite being skewed inexorably to negative. Little is known or documented regarding the intelligence of the most mature of these beings, but if they permanently retain the knowledge of their hosts and they truly do not age or die, it is possible that the oldest of these would have knowledge and experience far surpassing that of most men.

Perception and Sensory Capabilities

The umbral are aware of anything that happens in the shadows. After learning from their hosts, they can even use the shadows to see and hear things happening in lighted areas. Of course, being a parasite of the mind as much as the body, they also have access to all the senses of their hosts if they have one.
Their favored form of assessing their environments is touch. Much like a shark, they will come into contact with anything new to assess its palatability before deciding to attack or leave it alone.

Symbiotic and Parasitic organisms

Parasitic until fully mature

Lifespan

Indefinite

Body Tint, Colouring and Marking

A roiling black similar to static.