Shadows and Fallen Shadows

W. “These entities of darkness, also called Shadows, at first glance are a plague on the lower plain due to the primordials tampering with the balance of reality. In truth they are actually protectors of a person’s light and soul. Now this is fascinating. According to the lore, whenever a life begins a shadow is cast by its light. That shadow serves as its protector until the end of the person’s life. The light cannot leave the body without the shadows permission. But if it is forcibly taken away, the shadow will overtake the body and seek out its light. B. “Now these Fallen Shadows are the spawn of nightmares. Their charred looking bodies are actually harder than diamonds. They can rearrange the muscles and bones in their bodies so their arms become seven foot long spears. They also attack in a sporadic frenzy with claws and horns that can dig through solid steel like paper. They’re so fast that they can be a speck two miles away, then you blink and their arm is in your gut.”

Shadows are energy symbionts who bond to creatures of life and serve as their protectors. Without the consent of its Shadow, a person's will, life force, their soul if you will, cannot be taken away from them. In its natural form, the Shadow's purpose is to protect and ferry Light throughout its life. 
All things in creation cast shadows. Even the planets and stars themselves. Matter cannot contain excess (outside) energy and retain its stability. The shadows can absorb that energy to a point depending on the complexity of its host.
But it is possible to break the person, and through that method, break the Shadow. Cadmus was the first to discover this method of separating a Shadow and its Light. It was something they did to produce Etherion to power their weapons (see The country before Cadmus: Sodom). If the light is stolen from the body the shadows will possess the body and search for its light or a replacement. That is what creates a Fallen Shadow.
A body with a Shadow but no Light becomes a husk. Neither living nor dead, it is bound to a vacancy that can never be filled. To Consumed by that emptiness, they will search for weaker shadows so that they may take their lights. This process only results in the Light being lost and another being becoming trapped in the emptiness. In a way, being Fallen could be considered to be a communicable disease. The way to heal a Fallen is to give it a Source Light. The act of sharing one's light in contrast to stealing forms a sense of harmony that cancels out the shadows' corruption.
Normally when a shadow is bound to its host the energy it gathers is minute, taking the excess of whatever is left over the course of everyday life. However, if that individual has a higher concentration of energy than average, the shadow is able absorb that energy and grow stronger. They become more resistant to the Fallen and more able to preserve their Light.
For beings who cannot tap into this innate power, their shadows become vessels that fill with an individual's excess energy. Some species have a natural connection with their shadows and can tap into those reservoirs (like human Users). Others, who are more technologically adept, create devices capable of artificially bridging the gap (like Arketts do with their Etherion Resin Weaving).

Basic Information

Biological Cycle

Shadows have no proper beginning. They simply exist, and they travel, ferrying Light to and from the Source, finding fulfillment in protecting something precious, something that gives its existence value. 
They can be destroyed, if only temporarily, by taking damage from an Etherion-thing. This can be a weapon, a User, an Arkett tool, etc. And it's no surprise this hurts them -- imagine being attacked by the very thing you're trying to protect. Each Shadow, being individual, might take more or less damage before dispersing. But it's never permanent. 
Eventually the Shadow will re-form, and their state upon being re-formed depends on the *intent* of the light that destroyed it. Was the destroyer aware of what they were doing? If not, there will be little change. Was the destroyer intending to cause harm? If so, the Shadow is prone to be more malicious, more Fallen. Was the destroyer in fact doing their best to help? In this case, the Shadow has a chance of being reset to their benign state, pain eliminated, returned to their true purpose of protecting the Light.

Additional Information

Uses, Products & Exploitation

The purpose of a Shadow is to protect the Light. This means the beings are extremely useful to anyone who has learned to use Etherion, which is a lesser form of Light. 
Arketts capture Shadows in crystals formed from the resin of their sacred trees. Once captured in the crystal (the Shadow regards the crystal as a living body), the Shadow will collect, contain, and 'flow' up to their individual capacity of Etherion. Essentially, they become a rechargeable battery that lasts decades upon decades. Eventually the Shadow gets worn out - every being needs their rest - and the Arketts release them back into the Void they came from.
Users don't capture Shadows, but they unknowingly train their personal Shadows to increase their personal capacity to channel Etherion and fuel their User abilities. Again, the Users are ignorant of their Shadow's role in their abilities, but as they spend time training their core and gaining skills, the Shadow that protects their core grows with them. When the core is damaged, the Shadow is damaged too. If the Shadows had any kind of proper consciousness, they would consider this to be a symbiotic relationship, beneficial to both sides.

Civilization and Culture

Common Myths and Legends

When intelligence first came to be it was alone and afraid. It was not anything, and yet, it wasn't nothing. As its precious existence began to fade, it was preserved by the darkness around it. Shadows are the deities that have protected and gathered intelligences/light to itself. It doesn't have a consciousness as we understand it. More like it is the driving force of creation to protect that which is most precious: the sparks to life itself. The key to filling the vacancy of existence.