Unggoy

The Unggoy, nicknamed Grunts by the UNSC, are a sapient species and one of the former client species of the Covenant. The Unggoy occupied the lowest tier in the Covenant's caste system, and comprised the majority of the hegemony's labor force as slaves or serfs; consequently, they are near-ubiquitous across the Covenant sphere. While the Unggoy had some means of social mobility, either in special laborer duties, as merchants or in the clergy, few individuals were fortunate enough to have such opportunities.

Prehistory and rise of civilization
The evolutionary and pre-Halo history of the Unggoy is a difficult one to piece together, as the Forerunners kept few records on the species, and none of these go into any depth about what their society was like. As a result, most of what is known is based on speculations from human xeno-biologists and xeno-anthropologists, who are forced to look for evidence of their past in their anatomy and behavioral quirks.

The most readily-accepted theory is that the Unggoy evolved from a genus of amphibious, vaguely arthropod-like organisms with several primatoid physical characteristics. Early prehistoric individuals led tribal societies, and sustained themselves through hunting small animals and scavenging the corpses of larger ones. It is generally held that they were an important part of their ecosystem, where they were preyed on by Balaho's apex and second-order predators due to their numbers and considerable size. These often-unstoppable threats drove a number of early migrations outside of their home continent, while those that remained invented the defensive weapons and tactics they needed to survive. Over the centuries, this manifested in an instinctual fear of nature and anything that didn't resemble an Unggoy. Because of this, the history of their civilization was permeated with massive deforestation and culling campaigns, replaced with homes for their rapidly-expanding population. By the time the Forerunners came into contact with Balaho, little of the original wildlife and natural scenery remained.

They would reportedly develop themselves into a Tier-4 civilization by Forerunner metrics, where they enjoyed limited access to spacefaring craft. However, centuries of habitat destruction, over-industrialization, and pollution would lead to a massive environmental collapse, starving their population. The damage was only mitigated by the intervention of their Forerunner overlords, who implanted massive atmospheric processors and hydrosphere filters to stabilize Balaho's condition, and supplied alternative food sources. This was the end to their assistance, as the escalating Flood invasion saw them leave the Unggoy to deal with the problems themselves. By the time the Halos fired, they were still unable to meaningfully restore their homeworld's ecosystems.

There are some additional ambiguities to the pre-Array history of the Unggoy. The most prominent of these are the ruins on the methane-rich moon of Niihkta. The surface of Niihkta is littered with the crumbled remains of what appear to have been fairly developed urban communities, which in itself is not out of the ordinary as fallen planetary civilizations abound in the galaxy. What stands out are the carvings and inscriptions on some of these buildings, featuring elaborate murals depicting unmistakably Unggoy-like figures. The ruins remain a matter of controversy among Covenant scholars as Niihkta is nearly 1000 light-years from Balaho and the ruins there have been, with a slim margin of error, dated to be at least 180,000 years old. Many dismiss the carvings as a later forgery, while others have called the dating methods into question.

The Covenant
The first Covenant scouts would discover Balaho in 238 BCE, at a time where limited-scale industrialization was rediscovered among certain tribes. The surveyor's reports of a hardy but intelligent species that were eager to be taken off-world were initially treated with little fanfare. Their small numbers, low native technology level, peculiar native atmosphere and their consequent reliance on a methane supply outside it, initially made them of little interest to the Covenant as a whole. As such, they were made a vassal-species, but no concerted effort was made to integrate them to the Covenant hierarchy. Part of this was due to the Covenant itself going through a minor interregnum at the time, but another factor was the fact the Covenant's conversion process has not yet fully solidified, and there was debate as to whether such lowly and primitive beings were even eligible for Salvation.

Over the subsequent centuries, the Unggoy began to spread across the Covenant Empire, first as curiosities, entertainers and status symbols for wealthy magnates and nobles, then, more widespread servants and slaves. Increasing numbers of Sangheili aristocrats and warlords would foster small populations of Unggoy as serfs as well as cannon fodder in their internecine clan wars. Gradually, the Unggoy became embedded in the Covenant's power structure. Eventually, the usefulness of the species was re-evaluated by the bureaucrats of High Charity, and the High Council took steps toward a proper conversion process. Scores of Ministerial officials and missionaries were assigned to study the Unggoy, reassess their worthiness of the Great Journey, and convert them to the Covenant faith and way of life. By this point, many of the Unggoy in service to Covenant warlords had already accepted the Covenant religion, mostly with open arms due to the appeal of its message of universal salvation. They were formally elevated to the status of full signatory client-species in 214 CE, becoming the second race to be assimilated following the Writ of Union.

Social status
The Unggoy are, generally speaking, the Covenant's lowest-ranking species. However, there is still considerable variance in their social status, partly owing to how eclectic the Covenant is across its constituent domains. Not all Unggoy are slaves, though many are; it is also possible for some Unggoy to earn freedom; though this is difficult and often up to luck - or more pointedly, the local laws and the whims of the local lords. Like for the other species, social mobility for Unggoy often came through distinction—usually in war, but also peacetime; e.g. a Sangheili lord impressed by a servant might grant him and his family-community freedom or even an allotment for their own colony (or at least a self-governed enclave on an existing world), which was one of the most noted distinctions Unggoy could receive.

In terms of common Unggoy social roles, there are the thralls or slaves (which themselves vary from laborers and cannon fodder to fairly well-treated household servants, interpreters, etc); there is a laborer class resembling serfs, who enjoy more rights than the average slave but are still bound to their masters. Serfs were usually under contracts in which they would, at least in theory, be free after a set period of time; however, after that contract, the reality of the Covenant's labor market, such as it exists on the local level, usually means they just have to accept a new one. Finally, there are free Unggoy citizens or freeholders, some of whom can get by quite well with occupations like trade, though most are still laborers of some kind. Some specific duties, such as the religious role of Deacon, might grant Unggoy privileges and status most of them could only dream of. Still, even the wealthiest merchant or the most respected deacon would still be looked upon "only" as an Unggoy by all but the most enlightened Covenant citizens.