Tu'vok

“As human beings, we're born believing that we are the apex of creation, that we are invincible, that no problem exists that we cannot solve. But we inevitably die with all our beliefs broken.”

— Shaun David Hutchinson, We Are the Ants

A Tu'vok is a monstrous, body-snatching parasite hailing from beyond the stars.
A Tu'vok host is entirely indistinguishable from a non-host unless it wishes to reveal itself or the host is cut open to an unreasonable degree.
Due to this and their frightening intellect and supernatural abilities, Tu'vok are one of the most feared species across all the realms.

Biology

Tu'vok in their true form resemble monstrous slugs roughly the size of a cat. They are mostly a pale-white color, though if one is exposed to light for extended time periods its pigmentation may shift to a more natural looking color.
The slugs have no eyes or ears, they are blind and deaf. They are however still able to perceive the world around them through vibrations in the air and the floor.

In their natural state, the Tu'vok slug exhibits a number of unique abilities.

1. Regeneration: Tu'vok have prodigious self-healing abilities. Akin to a star-fish, they can regenerate endlessly so long as even a part of them remains alive. If a Tu'vok Parasite is cut in two and the two halves somehow remain alive, they have been known to regenerate into two new specimens. Their healing is not especially fast but it is seemingly flawless.
2. Adaptive Biology: The Tu'vok parasite is possessed of a highly adaptive biology. They can control their own biological processes, allowing them to segment off damaged portions of their body if necessary, change their metabolism to adapt to hotter or colder climates, change the texture and composition of their skin, compress or stretch their bodies and dampen their mental faculties to conserve energy. They are even able to enter a state of hibernation, remaining for years without any food, waiting.
3. Mental magic: Tu'vok have unique and powerful magical abilities, though they cannot make use of them without a Host. In this state, they can a most use them to somewhat perceive their surroundings.

Parasites by necessity
A Tu'vok is a very powerful creature, at least in theory. Their intelligence, their supernatural abilities and their regeneration should make them quite dangerous. Yet if a Tu'vok is ever without its host it will exhibit but a fraction of its true abilities, for one simple reason: Nutrition.
A Tu'vok is an obligatory parasite.
They have fangs, a mouth and digestive track, but they have no reliable method of themselves acquiring nutrients. They can digest almost anything, but their digestive tracks are so inefficient that they would run out of energy and starve even if all they did was eat.
Instead, in order to survive, a Tu'vok will instinctively use its adaptive biology to limit its intellect and mental magics in order to drastically conserve energy. In this limited state, a Tu'vok can survive for months or years with very limited food, though they will be slow, dull and impotent in this state.
A Tu'vok in its true form is in reality a stunted, diminished version of its full capabilities, barely clinging to life.

Alchemical Properties:
Tu'vok parasites are highly valued by Alchemists for their healing and other properties. Their bodies can be used to create powerful healing potions or magic-amplifying concoctions.

Parasitism

If a Tu'vok parasite is able to ambush a sleeping creature or is introduced to a restrained creature, it will enter the victims' skull by way of the ear, eye or nose. It will break any small layers of bone in the way if need be until it is able to reach the host's brain. This can also be achieved if a Tu'vok adult lays its eggs within a victim directly.
The parasite will then devour the victim's brain and in so doing will acquire its memories. It will proceed to fill up the victim's skull to the best of its ability and stretch its body along the victim's spinal cord, injecting small tendrils into the nerve strands all the while, allowing the parasite complete access to the body.
Within 3-24 hours, the victim is no more. The host's body will awake, no worse for wear, seemingly unharmed. The body will have been completely taken over by the Tu'vok parasite. Once it has assumed full control, the parasite will be able to make full use of the host's memories to perfectly mimic the victim's mannerisms, able to keep up appearances as if nothing changed, if needed. The Tu'vok will also inherit the hosts skills and most abilities, though it will also lose them again if it abandons the hosts body.

While latched into the metabolism of a host in this way, a Tu'vok will be able to use its full abilities without needing to limit itself for fear of running out of energy. It will be able to make full use of its mental abilities for whatever it deems necessary and its intellect will no longer be limited.

1. Regeneration: A host's body will be slightly healed by a Tu'vok parasite. Specifically, the host will exhibit slight regeneration. This is nothing major, but it will allow the host to eventually regrow lost body parts and heal scars, though it will likely take years. The host body will also be able to live long beyond its natural lifespan, supported by this regeneration.
2. Adaptive Biology: A Tu'vok's Adaptive biology can be used by the Parasite even whilst in possession of a host. The parasite will be able to control the host's biological processes, granting it small benefits such as allowing it to overcome its musculature's natural limits, normally imposed by the body to avoid hurting itself. The Tu'vok is also able to ignore any and all pain to its host body if it so chooses, along with being able to cut off blood-flow to injured areas. In effect this means a host will be slightly faster, stronger and more durable with the parasite than without.
3. Mental magic: If it is occupying a host, a Tu'vok is a highly intelligent creature and is gifted with strange supernatural abilities, sourced from its brain. They can with the power of their minds perceive the world around them akin to a form of echo-location, exhibit feats of telekinesis, can communicate telepathically with one-another, can stun and even kill with a mental effort.

From the moment of the parasite consuming the victim's brain, the host is dead. While they may retain their martial skills and even arcane abilities, magical talent gained through pacts or from divine sources will no longer be present, as such pacts are made with a being that is now dead; the Tu'vok merely pretends to be that creature while stealing its learned abilities. It is for this reason that Tu'vok will never possess a priest if their intent is to hide among the populace.

History

The Tu'vok keep their origins as a closely guarded secret from even most of their own population, but they were actually originally created not by any gods but by another species, one that is now extinct, in no small part because of the Tu'vok.
Originally they were a servant-race of infiltrator-killers to fight their then-enemies, but the slugs turned those selfsame abilities against their creators.

From that point onwards the Tu'vok engaged in milennia of reinforcing their world alongside raiding any and all nearby worlds for various creatures. They made no friends during those time but simultaniously remained a minor threat too costly to take out and as such were able to remain despite being alone.

They became true masters of flesh and form over the years and have had to rely on their slave raids less and less for survival and now do it almost purely for pleasure.

Culture

The Tu'vok culture is highly alien to human perceptions. They are highly hierarchical and focused on obedience, yet so long as the will of the superior is kept, any amount of personal indulgence and evil is permissible and even encouraged to keep the lower ranks happy.
The Tu'vok are an inherently parasitic species and as such they lack empathy entirely and as a result their culture formed not out of mutual cooperation but mental domination.
Weakness is to be taken advantage of, but so long as your superior is strong there is no point in trying to rebel.

Foreign species:
The Tu'vok hold little respect for any life-form that isn't Tu'vok, seeing them as tools and toys at best and pests at worst.
As a result, Tu'vok delight in taking slaves of other races, for a variety of purposes. Particularly noteworthy are those Tu'vok that enjoy rapidly switching hosts as one switches clothing, or those that enjoy feasting on the memories of new hosts. There is even some who like to bask in the psychic emanations of sentient creatures in pain, and thus do their best to facilitate that as strongly and as drawn-out as possible. Those captured by Tu'vok are not captured for necessity, but for pleasure.

Society

The Tu'vok have long ago conquered their own little pocket of the Brass realms for themselves. Whatever species they first conquered is long-lost to the eons, for nothing remains of them apart from the Tu'vok.

Independence:
The Tu'vok can parasitize almost any species found across the Brass Realms, yet they mostly choose to inhabit vat-grown hosts designed for this purpose. Created through a foul combination of alchemy, mental powers and necromancy, these creatures are born for the sole purpose of becoming hosts for the parasites.
Furthermore by use of their flesh-crafting the Tu'vok can create their own servants and with their powers control them to do their bidding. In this way the Tu'vok would be able to run an empire of mind-shackled slaves without needing to ever come into contact with the other sentient species' of the Realms.
However, the Tu'vok are not satisfied controlling weak-willed slaves created for the purpose of servitude. Their society has achieved relative stability millennia ago, now it is all about ambition and pleasures for the Tu'vok.

Tu'vok Hives:
Tu'vok settlements are sights of incredible horror for those that have even a shred of empathy within them. Only in Hades can one find worse conditions. Twisted spires and underground hives with alien architecture built for creatures able to levitate at will, dark slave-quarters with no shred of life-giving light that is not needed, Flesh-crafted monstrosities roaming the dark caverns and streets; Tu'vok hives are dreadful beyond description.

Hierarchy:
Tu'vok society is largely split into clans. Each clan has a 'Tyrant' which decides not only the actions the clan and its members shall take, but extends such tyrannical control over its members that it is the leader that decides which members of the clan may reproduce and create further Tu'vok spawn, all in accordance with their own plans for purposefully breeding a superior Tu'vok specimen.
Further below the tyrant are various ranks of Tu'vok nobility. Each rank holds those below it in a psychic hold, allowing for little to no free thought, at least in the immediate presence of a superior. However that simply means that acts of rebellion within Tu'vok society are done indirectly.
There are no Tu'vok menials, except for those who have been enslaved and now serve as entertainment for their fellows. Any manual labor or minor tasks are performed by legions of slaves and custom-grown bio-constructs.

Warfare

In combat the tu'vok can be encoutnered in one of two ways: as infiltrators and as warriors.

As infiltrators they will hide among their target population and carry out assasinations and spread general mayhem. They are comparable to adept sorcerers in the threat they represent but once uncovered an inflitrator's days are surely limited.

As warriors the Tu'vok use large warrior-constructs as dumb brutes to fight their enemies in melee while their more valuable psions support them as commanders and battle-mages. They use a variety of minor bio-constructs to assist the main force in a variety of roles.

Hunting strategy

A Tu'vok infiltrator is not able to be found by using obvious tells or some kind of physical or magical test. They have to be found out through investigating their actions or by getting them to reveal themselves by using their powers.
Most Tu'vok are endlessly arrogant creatures and will never take on an idendity that isnt at least nobility.

In combat, Tu'vok are comparable to mages, though more physically resilient and strong.

Appearance:

Tu'vok Hosts are indistinguishable from normal members of their species, unless cut open to such a degree that they are sure to die.

Tu'Vok Parasites look like slugs or worms, with fanged mouths with powerful biting jaws. They have no eyes or other visible sensory organs and are most often covered in a thin film of slimy mucus.