Sisters of Silence - An Ancient Order: During the Great Crusade, the Emperor kept a standing battalion of the Silent Sisterhood within His personal armies. They were tasked with hunting and exterminating those who would use their psychic talent against the Imperium or their fellow Humans during the wars for Imperial Compliance. Since that time, the remit of the Null Maidens has demanded that they wage near-constant war.The Sisters of Silence are rare pearls in the limitless ocean of Humanity. Each sister is one in a trillion, for the mental architecture of those who harbour the Pariah Gene is nothing like that of the common herd. They have only a startling void in place of that emotive, spiritual core that empowers and guides a typical Human. No simple absence is this, but a hungry, sucking abyss that makes even the spiritually inert feel unsettled and nauseous.It is this anomaly that makes the Sisters of Silence the bane of witches and Daemons alike. The Emperor once referred to this quality as a rare gift within His most esoteric servants, but in many ways it is an alienating, inescapable affliction. Yet in a galaxy where the shadows of Mankind's worst excesses are given physical form through the power of the Immaterium, it is indeed a precious resource. The sacrifice these Pariahs make is profound, but without it, Humanity may well have consumed itself long ago.Mankind's surety of purpose, restored by the tremendous success of the Great Crusade, was shaken to its core by the treachery of the Warmaster Horus. The corruption Horus spread through the Legiones Astartes eroded the Imperial Truth -- the secular wisdom, laid down by the Emperor, that saw the furtherance of logic and science required the outlaw of the concept of supernatural entities.The Emperor knew of the powers in the Warp that haunted Humankind, and had long sought to starve them of influence by denying their existence altogether, and spreading this belief among all those who came under His rule. Part of this strategy was the manipulation of the Pariah Gene, an extremely rare genetic anomaly that broke the link between the Immaterium and the material universe in the form of an individual Human being so blessed -- or afflicted as the case may be. Even the presence of a single Pariah is an ice-cold blanket over the fires of the soul, a suffocating chill that can turn a nigh-omnipotent psyker into a weakling ripe for slaughter.It was not through fear of His own boundless psychic talents that the Emperor waged His war of atheism, but through hope for a galaxy defined by order and reason. He resolutely denied His own godhood, even if it meant the most dire censure for His subjects who believed otherwise. To openly admit there were supernatural, psychic entities in the cosmos was to open a channel that the foolish and the greedy among mortals would seek to exploit, for the temptations offered by Chaos are boundless, originating as they do in the weakness and vices of Human nature. Thus, the Emperor was right to do so.As the Legiones Astartes began to fracture, the worship of Horus' new gods saw many psykers treat with Daemonic forces, creatures coalesced from Mankind's dark reflections and beliefs within the Empyrean. Some did so unwittingly, and the resultant manifestations tore tiny holes in the fabric of realspace -- holes that the fiends lurking behind the veil would gladly rip wider.Others deliberately opened such gates, dooming entire worlds to Daemonic invasion. Perhaps the most infamous example of loyal psykers turning against the edicts of the Emperor was that of the Thousand Sons Legion. The warrior-mystics' homeworld of Prospero died in flames after a punitive strike from the Space Wolves, the Custodian Guard, and the Silent Sisterhood who, by their very presence, forced the Thousand Sons to stop their use of outlawed psychic "magic" and the practice of "sorcery" -- bargaining with the entities of the Warp for knowledge and power.Such was their zeal and focus during the Horus Heresy, the Sisters of Silence were given unprecedented autonomy. They are trusted implicitly by the High Lords of Terra, for those deaf to the whispers of the Warp are amongst the most reliable of Human agents. Theirs is the duty of monitoring the masses via a network of trusted agents within the Adeptus Astra Telepathica.They then hunt down any untrained or rogue psykers they find, often alongside the agents of the Inquisition, particularly the Witch Hunters of the Ordo Hereticus and the infamous hunter-squads of the Black Ships. There are few other roles members of the Sisterhood could fulfil, for their talent is inescapable, and magnified by the Emperor's ancient artifice. Though they are trained to control their unsettling anti-psyker Pariah auras, projecting them until it becomes difficult even to look upon them, or suppressing them at need, the Sisters can never truly be rid of their genetic curse.After the Warmaster's rebellion was halted at the Siege of Terra and the Emperor was interred upon His Golden Throne, the Sisters of Silence found themselves without direction. Many were slain or lost forever, scattered and stranded across a war-ravaged galaxy. Undaunted by the sudden lack of guidance, they went abroad into the wider Imperium to continue their work. There amongst the stars they hunted rogue psykers and witches with unstinting fervour; some as part of the Adeptus Astra Telepathica, some as lone but loyal agents who eventually settled within the teeming hordes of Humanity.In some rare cases, these hunters learned to suppress their uncanny auras to some degree, and in living alongside others begot their own bloodlines. None of these would-be settlers ever stayed in one place for long, for the Pariah Gene is not named idly. Wherever the Sisters of Silence sought out new lives, they were hounded into exile once more by those that hated them for their intrinsic otherness.Still, not all were reviled or ironically burned as witches. The offspring of these few had children of their own, and over the generations, the genetic peculiarity of the Silent Sisterhood found its way further into the vast spread of the Human race.The Sisters of Silence have banded together but rarely since their devolution at the end of the Horus Heresy, with each major instance of their gathering for war expunged from Imperial records. Even then, their various orders remained divided by necessity, gathering only in secret.In the Terran years since, their numbers have grown, gradually but steadily, into the tens of thousands. Now, in the Era Indomitus, the Sisterhood is a vast army of psychic Nulls, standing ready to extinguish the dark flames of Chaos that threaten to consume the Imperium in the wake of the Great Rift's birth.