In my story, Endless Cycle of Exile, a young purple dragon chosen by Fate fight across dimensions and time against the parasitic semi-undead specie known as the Virii. No one knows where they came from and what they want... but one thing is sure: they are brutal, merciless, and powerful. They spread through the Realms like a virus, devouring everything in their path... hence the name: Virii.

The Virii types...

Vorii: Not all beings are killed when the Virii take over a world. No one knows by what standarts they choose... but some beings are chosen to be infested by Virii larvaes, thus being turned into Vorii. Still alive and conscious, the Vorii are the unfortunate zombified survivors of the Virii raids, condemned to see themselves work themselves to death to help the Virii effort until the larvaes have matured and burst out of their bodies, killing them.

Virii: The basic form of the Virii. Inside a Vorii, a Virii will slowly devour the victim's organs while keeping it alive, slowly replacing vital organs by its own as it devour the victim. Then, once the victim is totally devoured, the now adult Virii burst out. Then, the Virii seek out new hosts or, if they are intelligent or survive long enough, "evolve"...

Defirii: If a Virii live long enough, it will become either a Defirii or a Distil. Defirii are the twisted evolved Virii. Now self-aware and better equipped, those are major threats. They also have tentacle-like limbs that serve both as their feet... and as their gender. Those were named "Defirii" because of the horrible way they infest their victims.

Distil: Smarter Virii get turned into this. A free floating monstruosity, the Distil are low-ranked officers in the Virii hordes. They control Vorii and lower Virii, using telekinesis and other psychic powers to rule over their bethrens and bring death to their victims.

Vizeonir: If a istil is smart enough and survive long enough, it will become a Vizeonir. Vizeonirs are the Virii's high-ranked officers and scientists. Wielding powerful psychic powers and very capable physically, they float above the ground seeking to achieve whatever goal they might have in mind. Extremely intelligent, Vizeonirs are known to use their powers to pass themselves off as regular beings and spy other worlds, seeking potential next targets for the Virii hordes and monitoring the hordes' foes...

Fyzic: Not all Distils are fit to be Vizeonirs. Likewise, Defirii cannot become Vizeonirs. Thus, such Virii become Fyzics. Fyzicx are gargantuan monsters, as tall as a skyscraper and able to bring them one with one punch. Those violent, brutal beserkers have given up on their awareness and psychic powers for raw power. Those are the elite Virii warriors and are just as tough as they are tall.

Antirii: Defirii that are too smart to be turned into Fyzics become Antiriis. Those assassination units are silent, quick, clever, and effective. They fly at high speeds, beheading the enemies of the Virii using two double-edged scythes.

Siccophant: The Virii hordes are scary... and thus, cowards might join them in hopes of being spared the fate of a Vorii. Likewise, there are some who believe that they might gain power from the Virii. Such traitors are infested with a single, extra-special Virii larvae, becoming a Siccophant. Unlike the Vorii, who are helpless and controlled, the Siccophants live in perfect symbiosis with their Virii and are in full control of their actions. Often the shadows of former corrupt leaders, the Siccophants are rare but extremely powerful and high-ranked Viriis. Do not let the fact that they are in control fool you ; Siccophants are totally loyal to the Virii's cause and will fight to the death.

Omnirii: Wolrds that are totally taken over suffer the most horrible of fates. A special Virii larvae is injected in the very planet's crust and after months of growing, the very planet is infested, being turned into a massive Virii entity known as an Omnirii. The Omniriis are the supreme leaders of the Virii, their brains and queens. They constantly produce new Viriis larvaes through asexual reproduction and new types of Viriis through mating with Siccophants. As massive as a mountain, no one ever managed to kill one of those monstruosities.

Veinirii (not shown): The "God of Ruin", the supreme ruler of all Virii and the very first of all Omniriis. No one has ever seen this Virii and lived to tell about it so all that is known about it are rumors. Should this being exist, it is an abomination that is basically god-like in powers and that, thus, should never ever be allowed to break free of its emprisonment within the Dark Realm.