This title was bestowed upon them following their imprisonment in stone and eventual descent into what would be millennia-long silence and statuesque inanimation.
Much myth and lore surrounded the pair and much of their past was shrouded in mystery due to the violent and war-tattered beginnings of the vampiric race. What was known was that they were the original vampires, that the entire vampire legacy rested within them in some fashion or form, and that anything that befell them would befall their children as well.
Following the Genesis of the vampiric race, the Progenitors Akasha and Enkil sought to secure safety for the human race from a vampire race run amok. They attempted to pass themselves off as gods so that they could be both worshipped and cared for. The ruse was (relatively) short-lived, however, and mortals soon found out that immortality could be taken from them by consuming their blood.
The wars Akasha and Enkil were hoping to forego erupted in full force with two main factions: those who hoped to use their supernatural gifts for some kind of greater good and those would use those same abilities in a tyrannical or destructive manner. These times were chaotic, with both sides rising and falling with the tides.
At some point during these unrelenting skirmishes, Akasha and Enkil were captured and contained in diorite prison-cages, leaving only their heads and necks exposed. This way they could both take victims and be easily raped of their own ancient and most-powerful blood, all while also being rendered incapable of escaping, defending themselves or destroying themselves, thus taking the rest of their race with them into death. They spent centuries in this state, and in defiance of their captors, refused to feed from victims. This kept their oft-robbed blood from growing very much in strength, but also robbed them of the strength needed if they were ever to escape.
Over time, as with all vampires, whether they fed consistently or not, Akasha and Enkil developed the ability to leave their bodies in a form of astral projection. As with all vampires who live to come into this power, they faced the danger of it driving them mad. Being imprisoned in stone did not make it easier to cope with this power, and their bodies eventually became ever-vacant and rendered them little more than undead, marblesque statues. They neither killed nor fed during this time, and those who came to take blood from them did so without difficulty or struggle.
After centuries had passed, one night they were discovered to have broken free of their diorite prisons. Their clothing having long ago wasted away, they lay naked, embracing one another on the floor, though they endured in their lifeless state.
By this time, the wars that plagued the vampire world were long over. The magic surrounding vampires being worshipped as servants to the Mother Goddess in various incarnations had also died out, with only the most pious doing so in secrecy. What little information about Those Who Must Be Kept and their origins remained was cryptic, vague or unreadable by then-modern vampires. Although they were described as being the core of the race, it was unclear whether the core itself rested in either one, the other, or both. For this reason, they continued to be cared for by their "dark children" for several thousand years while they stared, open-eyed in silence.
Apparently, caring for Those Who Must Be Kept was a very tedious and time-consuming occupation. They had to be repeatedly dressed and redressed, they would sometimes take victims--but only inconsistently or when it pleased them. They even had to be washed and cleaned. (Marius at one point remembered that he hadn't wiped the dust off of their eyeballs in over a month and that he really needed to do it soon.)
Caring for them was also described as psychologically challenging as well. Their inanimate state was described as initially horrifying, then became more sad, and then, ultimately, annoying. Once the horror had passed, caretakers would feel pity, believing that the two were somehow imprisoned within themselves and could not escape. A common attitude by many in their early years of caregiving was that they would be able to somehow wake them from their centuries-long silences. Years and years of failure would result in disappointment and eventual annoyance due to some unusual experiences. Over the centuries, caretakers would find them as having moved, or having interacted with their environment in some way. Marius told Lestat that he would often find the doors or windows of their various sanctuaries open, even though no one could have opened them except him or another extremely powerful vampire. He also recounted how Akasha used her mental powers to repeatedly break a necklace he donned her with until he finally realized that she didn't like it. This and other bizarre occurrences happening under the care of various individuals led the individuals to become embittered or spiteful toward their charges, feeling that the only reason they wouldn't move was simply because they didn't want to.
One such individual, called simply "the Elder", became so irritated with them that he wished to be rid of them. He had grown tired of caring for them and disenchanted with being a vampire in general. Not believing what he called "the old superstitions", the Elder placed both Akasha and Enkil next to the Nile river before dawn and fled back to his coffin. The next night, he was horrified to find that "the old superstitions" were true and that his actions had dire consequences. Younger vampires the world over had burst into flames or were incinerated while they slept. Those who were older or more powerful were severely burned, blackened within their own skins and weakened terribly. Being powerful enough to survive the ordeal was far from a blessing, as survivors endured in unending agony until they healed. When the Elder went to retrieve the pair from the riverside, he found them both merely bronzed, and otherwise wholly intact. When any vampires would try to drink from them and be healed, the two would lash out and injure their children further, thus "proving" more of an ability to wake only if they wished to, which only deepened the Elder's resentment.
Following The Great Burning, an ancient "God of the Wood" made the then 40-years-old Roman Marius into a vampire and sent him down into Egypt to investigate what had happened. After the Elder revealed he had put Those Who Must Be Kept into the sun, and that he would probably do it again, Akasha temporarily became animate to stir Marius into taking them out of Egypt. She discreetly led him to their hidden chamber so that he might spirit them away. The fledgling Marius collected them into sarcophagi and planned to take them with him to Antioch where he would protect them himself. When the Elder arrived to take the pair back and to destroy Marius for his arrogance, Akasha erupted from her hiding place and annihilated him in a bloody shower of violence. After allowing him to drink from her, both to heal him and pass on blood-memories of their ancient, war-tattered past, Marius inherited Those Who Must Be Kept in full.
They would spend the next 2,000 years under his care and protection, and they would be moved from one sanctuary to another over the centuries. Just as Marius protected them, so would Akasha protect him when occasions proved capable for her to do so. She would also remove threats that were beyond Marius's reckoning, such as the vampire Akabar, who thought to drink from Akasha and become the most powerful of all vampires, only to be destroyed at the moment of truth. She would also allow Marius to drink from her to be healed or to give him further strength to protect them. She also served to "sanctify" Pandora's transformation into a vampire by allowing her to drink from her without recourse.
Soon after Pandora's transformation, and unbeknownst to either him or her, the ancient vampire Maharet had sought him out to conduct an experiment of her own. The Great Burning was scarce past by this point, and Maharet, who had been made a vampire at the dawn of the species, came to discover whether or not she could destroy Akasha. Maharet repeatedly struck Akasha and Enkil, but felt nothing herself. She then drove a dagger into the Queen's heart and felt her own heart stop along with it, confirming that Akasha's destruction would be her own. Though still feeling venomous toward the silent Queen, she accepted that her own will to live outshone her lust for vengeance, and she left the two in peace, albeit grudgingly.
Marius's care over Those Who Must Be Kept proved no more eventful for him than did the Elder's, and by the time Marius met with the vampire Lestat (some 1,800 years after inheriting them), he had grown weary of his duty, yet continued out of loyalty and responsibility. When a small stunt by the vampire Lestat led Akasha to both drink and be drunk from him, Enkil arose in a mindless, jealous rage, and attempted to destroy him. After threats from Marius and a physical resistance from Akasha herself, Enkil did not destroy the young one, and returned to his pedestal to sit in agitated silence.
This display led Lestat to hypothesize that the core of the race rested within Akasha, and Marius, who had suspected similarly, agreed that this was probably so. Over the years it had most often been Akasha who stirred, but only when one would attempt to take Akasha from him would Enkil ever take any sort of action. Following this escapade, Lestat was sent of to live a "mortal" life and Marius relocated Those Who Must Be Kept to a new location.
Some two centuries later, after the Industrial Revolution had led fully into the modern era, Marius felt a resurgence of hope that he would be able to awaken his charges. The birth of moving pictures and film (which had a profound effect on all vampires in that era, because they were able to see the sun for the first time since their mortal lives) did not stir them, however, much to his disappointment. By 1985 Marius had relocated his sanctuary into a technologically extravagant underground bunker in the frozen northlands of Canada. Following the invention of satellite-feed cable, Those Who Must Be Kept regularly spent their nights in front of a television, where the world could both reach and not reach them in their continuously inanimate existence.
When the vampire Lestat reawakened in 1985, he published an autobiography and promptly started a rock band called (fittingly) The Vampire Lestat. All of his songs were smash hits and his music videos were played around the clock on several stations. The themes of his music were centered around revealing the many secrets of the world of vampires to a public that would never believe or accept them (thus the novelty). This was done also out of his desire to do good by showing the world true evil, even if they didn't recognize it when they saw it.
His voice reached out and stirred Akasha, who, also a dreamer with a desire to do good, found a purpose strong enough to pull herself from her pseudo-imprisonment within her own mind. Upon realizing that her own purpose would require more strength than even she possessed, and also realizing that the creature by her side was far from capable of defending itself, she drained her immortal consort of every last drop of blood, effectively destroying him and bringing their silent reign to an abrupt end.