The Taint

Written by Heart

"We still don't know the exact details, so shrouded in folklore and lies based on fear. But, what we do know is that in bygone era's when the world was still one land, there was a dark entity that granted its servants drops of its blood. This blood was so potent that it was passed down to those servants children, and is continued to be passed down even now as diluted as it may be. Those with such blood are feared, and for good reason, it gave mortals tremendous power."

— Archmage Zeldric Romun

Tainted species have two separate tiers, those with unawakened blood, and those with awakened blood. Unawakened blood allows the host only the most innate and passive of effects connected to the dark magic coursing through their bodies. This is reflected in their pitch-black blood to represent their tainted existence of holding a fraction of the power that by natural law, only the primordial beings are meant to ever have.
As well, all of the Tainted hold abnormally potent negative emotions, and desire for freedom in its purest sense. To what degree varies on the individual, but they cannot avoid this nature that resides within them. Often this develops into psychological issues. They tend to be sadistic or sadomasochistic, or simply have strong negative emotions that they struggle to control, such as anger or depression. It isn't uncommon at all for great warlords to have Tainted blood passed down to them, explaining their tendency to conquer, pillage, and slaughter without hesitation or care.
It is to be noted that the blood only amplifies these feelings, however, and it can be resisted. There can be "Good", Tainted beings as much as there can be "Evil" normal beings.

Suffering the Taint

The process of suffering the taint is complex. One must be directly exposed to the black blood into their own bodies from the blood of a tainted, or corrupted (see below) creature. This will then result in the blood being "infected" by the taint. However, much like a sickness, this can be resisted by the body and mind. Depending on the individual's race, the quantity of tainted blood, and how it makes contact with the individual the infection rate can vary tremendously.
However, after an infection has begun and cannot be resisted, the rest depends on the host in question. Depending on their genetics (primarily the trace of genetics back to a Fristborn ancestor of some sort), willpower, health, and the process of exposure the individual will go through one of four options.

Immunity

A fairly common (by comparison to the other options) outcome among most humans and those lacking any firstborn genetics running through their veins, these individuals when exposed to the taint and corruption not only resist its mutation and painful effects; but build upon the cursed sickness. Augmenting their natural resistance to sickness and toxins, granting them complete immunity to the taint and all of its variant strains. This also grants them enhanced physical health and incredibly high resistance to other toxins.

Tainting

Becoming a tainted is often viewed, in the form of raw benefits, as the "best" option. The individual becomes what is known as a true "Tainted". Though they suffer weaknesses to natural light and heat, they are grossly more powerful than most individuals of their species. Often being noted as far denser than normal members of their species. They will gain physical strength and durability several times that of their species, with immense magical power and stamina reserves. This will also augment their lifespans, tending to triple to quadruple their natural life expectancy and allow them to heal from minor wounds in minutes, and more serious wounds such as broken bones in a mere week.
The only physical change being that their blood turns black, and their veins will darken. However, they will suffer from a sensitivity to natural light. Being easily sunburned, and intense light can easily blind them. A weakness to intense heat is also quite common, as is a consistent allergy to all forms of 'Pure' metals. Though silver is most commonly used, other pure metals are also viable such as iron, lead, etc. Contact with these metals will cause an instant rash, and intense pain that nullifies their advanced recovery rate they normally have.

Corruption

The second "best" outcome, though some would argue this, is the most common reaction to the taint spreading. This is most common in plantlife and other non-sentient life, but will spread to sentient, and even in some situations sapient life as well. Corruption is the result of a host whom is strong enough in health to survive the process of the taint, but lack the genetic irregularity required to accept the taint properly.
As such, they instead begin suffering a rapid onset of mutations that change their anatomy and often their size. Granting far more raw benefits than a normal taint, but in return magnifying the weaknesses of the taint tremendously. These mutations are painful and often viewed in the light of something akin to cancerous, but far more serious. Growing additional deformed limbs, organs, eyes, etc. Their downsides are also magnified, causing natural light to instantly turn most corrupted creatures to ash over a few seconds of direct contact.

Death

Finally, the last option for those whom suffer the taint beyond simply resisting it successfully in the first place is to die. Painfully and slowly in a sensation, many have described in screams of pain as similar to their 'organs cooking' and 'veins full of lava'. The process can take up to weeks, and often by the third or fourth day after failing to resist the taint will generally be put out of their misery by others.

Pure Blood

The rare few whom are considered of "Pure Blood" are generally only the Royal Daevata. But technically any creature whom is directly "Sired" by the blood of another Pure-Blood, or the Daemon itself directly can be called such. Pure Blooded beings have all the benefits of being tainted, and yet suffer none of the normal drawbacks and weaknesses aside from their allergy to pure metals. Yet in return, their appearance is far more easily distinguishable from their unawakened brethren.
Their skin will change in hue to become unnaturally smooth, perfect. Old scars and wounds they had will gradually begin to fade over time no matter how serious the wounds. Their veins will become easily spotted, turning pitch black. Their blood will retain its tainted, ebony pigment, and yet will hold undertones and streaks of purple, akin to the reaction of light to oils. Their cuspids will increase in size, and additional cuspids will grow from their jaws. They are similarly able to activate a unique "State" which grants them significantly increased prowess, elongated claws and cuspids, black sclera, and even greater physical abilities. Every Pure Blood will also tend to have unique additional traits, based on their root bloodline such as wings, horns, carapace-like skin, etc.

Awakened

The awakened, a sub-species now practically extinct, are the rare chosen Tainted that had their blood strengthened through a dark pact with the Daemon, the being offering a fragment of its own soul to the chosen. If accepted, they were overwhelmingly powerful compared to others that held the taint. But suffer from nightmares and whispers connecting them directly to the Daemon itself due to a fragment of its soul being hosted within their own souls. Along with this power amplification, their regeneration is the most notable increase in their passive capabilities, being rendered effectively immortal.
The fragment of sentient divinity also tends to offer its host access to forbidden magics only usually wielded by the Daemon itself. Often including the knowledge of a powerful True Name. The awakened retain all of their abilities as the normal tainted, but have their powers magnified even further. In appearance they are no different from their prior blood; but their mana is notably pitch black within the Ethereal Plane instead of the normal silver and other colors.

Origin/Ancestry

The Daemon

Lifespan

Up to quadruple their standard species average.