Background
Relatively little is known of the current Chapter Master and Chief Librarian of the Blood Ravens Space Marine Chapter. What is known is that 1,000 years before the Black Legion's invasion of the Aurelia system, planet Aurelia disappeared during a Warp Storm, after being pushed so far out of orbit that the planet froze with icy glaciers and killed almost all of the populace. Sometime just before the planet was taken by the Warp, Librarian Kyras managed to imprison a Greater Daemon by the name of Ulkair, after his master Moriah was killed by the daemon. Soon after, the warp took the planet, and Azariah Kyras with it.
Kyras eventually returned some centuries later, appearing before the battered elements of the Blood Raven's 5th Company, as they attempted to board the Space Hulk 'The Judgment of Carrion'. There, showing up inexplicably, Kyras aided Apothecary Galan in successfully escaping the Space Hulk. However, Galan reported Kyras' depressive behavior, mentioning that the Librarian told his earlier exploits against Ulkair in a melancholy manner, damaging morale.
Both Galan and Kyras escaped The Judgment of Carrion, and Kyras' return was hailed as a blessing by elements of the Blood Ravens, but not the Captain of the 3rd Company, Gabriel Angelos. Sometime thereafter, Azariah Kyras rose to the rank of Chief Librarian, and Chapter Master.
The Black Legion's invasion into the Aurelia sector however, has revealed that Kyras has fallen to corruption and chaos. Furthermore, a daemon who possessed Librarian Jonah Orion admitted that Kyras taught him how to disable a Librarian's psychic hood, causing Orion to fall to daemonic possession while assisting Angelos and 'The Litany of Fury' in their attempt to break through the Tyranids on their way to planet Typhon during the Great Devourer's attempt to consume the Blood Raven's recruiting worlds.
Kyras was not in the Aurelia system during the Legion's invasion, instead having sent Captain Apollo Diomedes of the 5th Honor Guard Company in his stead. According to a confession by Apothecary Galan, Diomedes himself is not corrupted, but men under his command are. Final sources state that Captain Gabriel Angelos goes to war with Azariah Kyras, creating a prologue to a chapter wide civil war amongst the Blood Ravens.