Invid Evolutionary Castes

The Invid are often compared to insects, a comparison that, while lacking in nuance is also not without merit. Like many insect species, they are divided into distinct castes based on their role in society and those evolutionary features that they possess. Likewise, they are a part of a collective hive intellect, controlled by an all-powerful queen, the Regiss. That queen dictates the existence of the Invid at every level from controlling reproductive cycles to directing their actions.

However, there are also many differences and points where the comparison breaks down. Possibly the most important of these is the fact that the Invid have the unique ability to control their own evolution. While an Invid may be hatched into a specific caste, they can be 'promoted' and uplifted to a more advanced role through a variety of means. And while it is a gross misrepresentation of the evolutionary process, the Invid's controlled evolution can only be described as 'upwards’, with each form becoming more advanced than the last.

There are seven known Invid castes (even if two of those are in doubt; see individual entries to follow) that, for the most part, represent a linear process of advancement from one form to another. However, it has to be said that this does not exclude the idea of subcastes by any means; rather these represent the most commonly seen expressions of those castes. Unfortunately, biological study of the Invid is near impossible; most lower castes cannot survive outside of their Mecha, a biological adaptation resulting from their own forced evolution and rapid militarisation. Likewise, most Invid will begin to break down once dead, making examination of corpses difficult at best. Finally, it has to be said that there may be a number of other evolutionary forms that have been discarded, have become extinct or even are simply unknown outside of the Invid.

## Stage I: Slug

The simplest form of the modern Invid, the Slug is believed to somewhat resemble the Invid in their pre-contact form. As the name suggests, the Slug resembles nothing so much as a massive slug, approximately 1 meter in length. This form lacks any limbs and crawls on its belly, serving to only further the comparison (although some subcaste examples have primitive limbs that allow them limited locomotion). The Slug is entirely dependent on its Mecha to survive, and will die if removed from its systems within minutes. However, Slugs may be preserved in independent stasis indefinitely. The Slug is the most common form of Invid, and is believed to represent the majority of extant examples.

As the lowest form of Invid, the Slug lacks any sort of individuality and ability for individual thought, or any sense of self-preservation. Normally they will act instinctively, protecting their 'territory' against anything seen as being hostile to the Invid, and mindlessly lashing out any intruders. The suicide attacks used by Invid Scouts (piloted by slugs) against UEEF spacecraft are typical behaviour of the type. Mecha controlled by Slugs typically travel in aggressive swarms and act in cohesion with each other, but rarely display any tactical acumen beyond bearing down on their targets with superior numbers.

However, the Slug's capacity for individual action markedly increases when they are being controlled by a more advanced part of the hivemind. This can be an Invid Brain, the Regiss, or even a Stage IV or V caste Invid. In those cases, the Slug can become far more cunning, given to ambush tactics or even directed attacks at specific targets.

The Slug normally pilots the Invid Scout mecha and its assorted variants.

## Stage II: Worker

The Worker is a radical departure from its predecessor. It is bipedal, standing approximately 1.5 meters tall with thick arms sporting clawed hands and a simple, mouth-like orifice. While still clumsy, it is capable of crude locomotion and manipulating objects. Its internal structure is more complicated, featuring more developed organs. Like the Slug, the Worker is entirely dependent on its Mecha to survive, and will die within minutes if removed from it. The Worker represents the second most common form of Invid.

Like its predecessor, the Worker lacks any form of individuality, but it does possess a limited ability for individual thought and awareness. Workers may be 'trained' to perform specific tasks, although how this is accomplished is unknown. They are employed in the construction of Hives, Broadcast Towers and other Invid structures, as well as other labour duties. Likewise, they display somewhat more tactical awareness and ability in combat. Workers will sometimes bury their own Mecha and then wait in ambush for an opponent, their life support systems allowing them to remain in place indefinitely. However, once engaged, they will still lash out at the nearest target or relentlessly pursue it.

As with the Slug, the Worker may also be directed by more advanced Invid towards specific tasks. It is believed that this process is often used when the Worker is tasked with specific labour roles that are beyond its usual instinctive capabilities. Likewise, Workers piloting the Mender mecha may be tasked with protecting and healing specific Invid, rather than tending to the nearest injured.

The Worker pilots the Trooper and Mender Mecha, and the unarmed models of the Soldier Power Armour.

## Stage III: Warrior

The Warrior is the next most advanced caste of Invid, and represents a more conventional evolution of its predecessor. The Warrior is humanoid in form, albeit with a hunched back and a small head. Its limbs are still chunky, with its hands and feet featuring three claws. The Warrior has a more advanced internal structure, but is still dependent on its Mecha to survive. Warriors will die within minutes of being removed from their Mecha, but are far from helpless when such happens. The Warrior represents the third most common form of Invid; while less common than the Worker, its is believed that their proportional numbers increased dramatically during the Invid occupation of Earth.

Compared to the lower castes, the Warrior displays far greater capacity for individual thought and action, and is believed to possess some degree of individuality. Warriors are by nature aggressive, but are not mindlessly such. Rather, they are capable of stalking opponents, staging ambushes or even picking out and deliberately targeting individual enemies rather than simply lashing out at the nearest foe. Warrior-caste Invid have even been known to withdraw when damaged or injured, although they are more likely to fight to the death like other, lower-caste Invid.

As with the other lower castes, the Warrior may be directly controlled by the Regiss or an Invid Brain. In such cases, the Warrior will often be used to lead other Stages I-III Invid in the field or direct operations in an area remote from the local hive. It is also possible that those instances of Warriors being used to attack specific targets were while they were under such control.

The Warrior normally pilots the Shocktrooper and Grappler, as well as the armed models of the Soldier Power Armour.

## Stage IV: Keeper

Prior to the Invid's occupation of Earth, the Keeper was the highest form of the Invid, and was a significant departure from the previous forms in terms of capability. The keeper stands about 1.8-2 meters tall with a humanoid form, with a long, slug-like neck and a 'face' dominated by pair of pseudopods. The limbs are thick and fully formed, and feature four-fingered hands. Unlike the previous forms, the Keeper is capable of surviving indefinitely outside of its Mecha. The Keeper is the least common of the traditional Invid forms, but represents only a tiny proportion over the overall Invid population.

The Keeper is fully capable of independent thought and reasoning, and has some degree of self-identity. However, it is still fully integrated into the Invid’s collective consciousness, and is still bound to the Regiss. Keepers have demonstrated a clear ability to recognise individual humans, and are capable of communicating with non-Invid life-forms; as such, they were the usual method of interaction between the Invid and collaborators during the occupation.

In the field, Keepers usually act as commanders for groups of less-evolved Invid. It is rare to see more than one Keeper at a time, but groups of them were observed during the massive second Battle of Reflex point. Keepers are capable and cunning opponents, and will adapt their tactics to suit their situation. However, this will not stop them from fighting to the death if needed. Typically Keepers pilot the Enforcer, as well as the armed version of the Soldier Power Armour; in the latter role, they will usually command squads of Warrior-caste pilots.

The Scientist caste found within the Regent’s Invid army is a subcaste of the Keeper-caste. Responsible for the creation of the Regent's weapons, it is believed that they have undergone further modification to augment their cognitive faculties. They have also been observed to display a greater degree of individual behaviours and autonomy. Some have even suggested that the Regent himself was actually a highly developed example of the Subcaste.