Yuan-ti

The Yuan-ti are not a divine creation, and not originally a true race.
A fledgling human kingdom in the tropical regions of Cathlaea was stunted in its social development when its territory fell into the shadow of the Legion-Regime Wars. Nascent state structures were replaced with military governorships, even as the dominant tribe of the region was on the verge of bringing its neighbours, through diplomacy and coersion, into a union. As their people were used as fodder in the wars, the priests of these tribes sought the aid of the gods and spirits who had always watched over them and found... something else. They fell under the influence of a trio of dark gods known as the Three-Headed Serpent, who gifted them with the power to fight back against the technological and logistical supremacy of the Regime and the Legion.
The priests of the Three-Headed Serpent freely loaned their power to the tribe, and steadily guided their chiefs on a path to worship the Serpent in place of the old gods. As the great powers fell back under the weight of internal strife, these tribes absorbed others, and the priests mandated a dramatic increase in the bloodiness of the tribes' rituals, demanding ever-greater levels of animal and humanoid sacrifice to please their gods. The Serpent grew in power and in hunger as the chiefs became kings, and the cult offered ever more extravagant boons to the nobles who pursued the most aggressive programmes of conquest, overthrowing other tribes – mostly human or Lizardfolk – and offering their blood to the glory of the Serpent until avatars of the three came forth to further goad the people on to war.
As the kingdom waxed into the Great Ophionic Empire, its rulers looked upon the avatars of the Serpent and conceived a great disdain for their own soft-skinned bodies, so similar to those of their slaves and victims. The priests, guided by their gods, devised ever more depraved blood rites, culminating in the rituals and the elixir called the Blessed Venom, which transformed the priesthood and nobility into the serpentine horrors that would become feared by the name of Yuan-ti.
Many of those 'blessed' were killed, others transformed into bestial monsters, but over time the rites and the Venom were perfected. The strongest became the serpent-bodied abominations, the most devout the twisted malisons, the rest the almost-human snakebloods. The Blessed Venom also affected the children of those it transformed. Some were born as snakebloods; those who were not were dubbed ‘halfbloods’, and might hope to take the Venom later in life. In the reign of the third emperor, the malisons presented a new elixir, the Divine Venom, by which the most revered of their leaders were empowered to take a new and even more powerful form; that of the anathema.
Under the rule of the now-inhuman noble houses, the empire grew and grew. Enemy elites who surrendered - or betrayed their own rulers to the empire - could hope to undergo the rites and become Yuan-ti, a fate open to both human and petari. The rest of the empire was dominated by fear and blood, its economy driven by vast numbers of human and petari slaves, and geared towards feeding the temple pyres. At last, however, they became victims of their own terrible successes. Neighbouring states banded together for defence, curbing the expansion of the Empire and starving the blood flames. Faced with the alternative of sacrifice, many slaves took the risk of escaping their bonds and fleeing north, or south across the ocean to Suto. The noble houses turned on one another, battling for land, slaves and sacrifices, until at last the Empire fell into anarchy and civil war. The pyres went hungry. External enemies pushed at the borders, most notably the Ash Elves of Benefice Zeranzeri, and the power of the priests declined as their gods weakened and turned away.
The Yuan-ti survived, however, and as in strength they fell, when reduced they flourished. They now rule the much reduced Second Ophionic Empire with the same dread and scaled grasp.

Yuan-ti and Identity

The remnants of the first Empire’s strongly gendered human society remain behind the dominant caste structure of their current dominion. Their original culture was deeply wedded to biologically determined gender, and strictly prescribed gender roles within society. Men had charge of matters military and diplomatic, hospitality and the economically and politically critical giving of gifts, while women determined domestic policy and undertook work in espionage, logistics and trade. In the pre-Ophionic tribes, women owned land. A landowner would gather a household of other women about herself, and assemble a cadre of men – mostly related by blood or marriage – to protect it. Women brought brains and money to the household, men brought muscle and charm.
The rising Ophionic Empire largely replaced these gender roles with the blood castes, the various levels of serpent transformation undergone by individual Yuan-ti. Biological sex is of trifling importance to the Yuan-ti, especially compared to blood caste. The highest priesthoods of the Three-Headed Serpent are strictly gendered – Stygis’ nightmare speakers are female, the mind whisperers of Sythis are strictly male, and the pit masters of Asphyix non-binary – but this is a matter of presented gender and not biology, as holders of those offices seek to better emulate their patrons and become closer to them.
The lowest blood caste is slave, held by those - human or otherwise - without any degree of transformation, and thus unworthy of personhood. While slaves in the Empire tend to maintain their own traditions of identity, to the Ophionic culture they are all ‘it’, mere genderless things
Above slaves are halfbloods, the children of yuan-ti who do not possess sufficient ophidian characteristics to be classed as 'snakeblood,' either through interbreeding with other races, or as a quirk of genetics. Typically assigned to the lot of a slave, halfbloods are shown preferential treatment, especially if they prove especially strong or clever. Particularly favoured halfbloods may be chosen for transformation into true Yuan-ti through the Blessed Venom, although this is almost unheard of in the Second Empire. Other slaves, meanwhile, are never offered the venom, but may be subjected to the Serpent's Blood, which instead transforms those drinkers who survive the experience into the bestial servitors known as broodguards. Broodguards are valued for their strength and unthinking loyalty, but given no status in the Empire.
The lowest caste of Yuan-ti are the snakebloods, sometimes called 'trueblood' because they bred true. Born either oviparously or viviparously, they are the children of either snakeblood or malison parents and are accorded the barest minimum courtesy by their transformed kin. They are accorded the dignity of a gender of their choosing and are considered people, at least, although more to remind halfbloods and slaves of their place than to honour the snakeblood. Within the Empire, it is the snakebloods who perform all of the skilled labour - diplomacy, artistry, crafts and others - that is considered beyond a mere slave, but beneath the higher castes.
Snakebloods compete in various examinations and competitions to earn the right to become a higher form of yuan-ti, the transformation catalysed by ritual and elixirs. Most of those who prevail in these trials will be elevated to the rank of malison, their humanoid form strengthened and partially transformed by serpentlike features, although a few meet the same fate as early recipients of the Three-Headed Serpent's blessings and die. Malisons fulfil priestly and advisory roles, communing with the gods and managing much of the day to day life of the Empire. Like snakebloods, malisons both have biological sex and use gendered pronouns. The children of two malisons will be snakebloods, but enjoy an unofficial favoured status among their blood caste.
Favoured Malisons may one day be granted accession to the status and physical state of abomination, an almost entirely ophidian form, but with powerful arms. A vanishingly small number of snakebloods may also ascend directly to this state on first imbibing the Blessed Venom. Such individuals are known, even as abominations, as truebloods. Powerful and cunning, abominations form a lordly caste and in particular act as military leaders. They do not use gender as a construct, instead using the pronouns sse/ssir/ssirs universally. Only a few retain any vestige of biological sex, and those who do go to great lengths to disguise the traces.
Finally, Anathamae are the ultimate 'evolution', created using the most powerful of elixirs from favoured abominations. Larger, stronger, all-but immortal and blessed with an array of six heads, they are the rulers of the Empire and seen as incarnate demigod children of the Three-Headed Serpent. No abomination has been granted the ascension to anathema status since the dawn of the Second Empire, however, perhaps to avoid creating potential rivals to the Emperor. Anathemae use the pronouns hha/hhar/hhas, which are forbidden to all lower forms.

Yuan-ti and Evil

Some see the Yuan-ti as inherently evil, but this is not entirely true. While the Ophionic Empire is cruel, supremacist and bloody, these qualities are not genetic, but taught. Snakebloods are taught that they are superior to slaves and inferior to the 'higher forms,' but nothing in their nature makes them adhere to a specific philosophy. The higher forms are different, invariably vicious to the bone, because only those who show an absolute, fanatical devotion to the blood creed of the Empire are granted that ritual ascension and physical transformation.