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Brotherhood of Certain Fates
As indited by Haruspex, the Immortal Archivist:
Believed to be a secret faction within the Solar Deliberative during the Median Resplendent Period, the confirmation of their existence is now largely relegated to comparing legends and spoken records. (All references in Yu Shan have, of course, been suppressed, but resources are currently being expended to recover the misappropriated items.) The fraternity was formed by a trio of Twilight Caste Solar Exalted, all veterans of the Primordial War, after a prognostication performed in secret (aided by the incomparable Artifacts each commanded, including the legendary Answer Stone and an apparently complete set of Divination Helixes) revealed a Sidereal plot to undermine the Celestial power of the Deliberative (some fifteen-hundred years before the Usurpation). Unable to betray the results of their unregistered divination to the Deliberative without consequence, they instead formed a secret organization within the Council: the Brotherhood of Certain Fates.
Creating false identities and cloaking themselves in artifacts to hide themselves from Fate, the Brotherhood (numbering between 30 and 60 Exalted at its height, composed largely of Solar Exalted, with lesser numbers of Lunar Exalted, and a handful of renegade Sidereals) had hoped to cripple the Sidereal plot and discredit its leaders while remaining anonymous, but any chance at a secret resolution was made impossible with the Night of Wandering Stars, signifying the start of the Maiden and Shadow War, also known as the Secret War.
As the Secret War hit its final apex, the Brotherhood began to shatter, disrupted by backstabbing amongst its leaders and the disagreement about the rituals and bindings that held their Demon shock troops in thrall. The fates of the founders diverge wildly from this point on.