The Pillars were corrupted by the machinations of "dark forces" in the pre-Blood Omen era, and they later collapsed when the Balance Guardian, Kain, refused to sacrifice himself to restore them in the Blood Omen era. His decision had implications for Ariel, the specter of his murdered predecessor, who was thereafter condemned to haunt the ruined stumps of the Pillars indefinitely. However, the dire ramifications of their fall extended far beyond one individual. As long as they remained unrestored, corruption seeped into the land like a poison; they were inexorably linked to the redemption of Nosgoth.
Most of Kain's existence was devoted to seeking out a means of restoring the Pillars, leading to numerous discoveries concerning their origins and purpose. It transpired that they were much more than a human edifice: they had been originally raised by the Ancient Vampires, as a weapon of war against the Hylden. The Binding which the Pillars maintained ensured the integrity of the barriers between Nosgoth's Material, Spectral, and Demon Realms. Furthermore, the Elder God lurked in the Subterranean Pillars Chamber beneath their central dais, its tentacles coiled around the nine ancient edifices, and its intentions inscrutable.
"How strange to see this place long before my birth... centuries before the corruption set in that would poison the land, and put me on the treacherous path I still followed. In the future, these edifices would be condemned to darkness and decay. I would cause their fall, and build my empire upon their ruins. Was it still possible that with the right knowledge, the right moves, I might one day see Nosgoth restored, the Pillars pure once more? My answer – according to Moebius – lay somewhere to the west of this place. I could restore the world, perhaps. But never again could I give Nosgoth back her innocence."
"My murder at the hands of this beast drove my love Nupraptor mad. Now he spreads misery and pain among the Circle, crumbling the very foundation of Nosgoth. You must restore balance. You must right the Pillars of Nosgoth."
The Hylden rejected the god of the Ancient Vampires and their laws regarding the Wheel of Fate. This ignited a war between the two races, with the Ancient's ultimate goal being to banish the Hylden from their land altogether. The Ancients constructed nine pillars representing the most fundamental elements of their world, and, using their magic, used these Pillars to send and lock away the Hylden in the Demon Realm. As long as the Pillars could adequately be served by the Vampires, the magic would be strong enough to keep them banished.
However, on their departure, the Hylden cursed the Ancients with immortality, cutting them off from the Wheel of Fate that demanded their souls be returned to their God and re-spun in the wheel. They also cursed them with sterility, ensuring the extinction of the species and the discontinuation of the magic that preserved the Pillars.
The Pillars chose their guardians from birth, and since Vampires were no longer born, new subjects had to be created to sustain the Pillars. Humans were selected by Vampires to be given their dark gift and to serve the Pillars as vampires alongside their masters. The humans eventually rejected the gift and overthrew their superiors, claiming the Pillars for themselves.
However, the Pillars could never be adequately served by the humans, and the magic began to weaken, allowing a particularly powerful Hylden to slip through and set into motion a plan to bring down the Pillars altogether.
The Hylden Lord, projected his soul through the dimensions and possessed the body of Mortanius, the current Guardian of the Pillar of Death. Using this body, he murdered Ariel, the Guardian of Balance. This in turn drove her lover, Nupraptor - Guardian of the Mind - insane, who then infected the rest of the Circle of Nine with his madness. All of this was calculated carefully by the Hylden before-hand.As the Circle descended into madness, the Pillar's magic faltered and the Binding became weaker.
Mortanius, during brief moments of clarity, was able to set in motion a prophecy foretold by the Vampires upon the human rebellion, in which a vampire would one day return the Pillars to the Vampires and thus ensure the binding never fail. He had the nobleman Kain killed and turned into a vampire. Kain was then directed by the ghost of Ariel to murder the remaining Guardians before their madness utterly destroyed Nosgoth. Kain proceeded to do so, and battled Mortanius (it remains unclear whether Kain knew at the time, about Mortanius' possession by Hash'ak'gik). He apparently killed him and Ariel revealed to him the truth of his destiny - that he himself was the final Guardian, the Guardian of Balance, chosen at birth upon Ariel's death to succeed her.
Tainted by Nupraptor's madness, as with the rest of the Cirlce, Kain rejected the sacrifice and chose to conquer Nosgoth. In that moment, the Binding failed, and the Pillars collapsed. The Hylden were free to enter Nosgoth and begin wiping out all other species.
Some time later, having quashed the Hylden invasion, Kain built the seat of his empire, the Sanctuary of the Clans, around the base of the ruined Pillars in an act of irony, with the central pillar, the Pillar of Balance, as his throne.
As Kain matured, he realised the gravity of his destiny, and the effect of his actions, and dedicated himself to restoring the Pillars by altering the time-stream, specifically using the rogue-element and singular variable of Raziel to do so. He learned of his role as the Scion of Balance, who would return the Pillars to the Vampires, and of his destiny to restore the Pillars altogether. However, the journey to do so would be difficult given the corruption he had inherited from the Circle.
The Pillars represent nine fundamental elements of Nosgoth. Each is served by a Guardian who inherits certain affinities and abilities relating to their given Pillar. For example, Moebius, the human Guardian of Time has the ability to see into and manipulate the time stream.