Mephiston

Mephiston is the Chief Librarian of the Blood Angels Space Marines Chapter. Originally known as Battle-Brother Calistarius, he was a Librarian of exceptional valour and strength of character. Yet the Black Rage cares not for the nobility of the soul, nor the deeds of the flesh. Whilst fighting before the walls of Hades Hive, during the Second War for Armageddon, the curse of Sanguinius finally stole upon him. Inducted into the Blood Angels' Death Company, Calistarius took part in the final assault on the Ecclesorium builiding, and was one of the many people crushed under the falling debris when the building collapsed. He was buried under the rubble for seven days and seven nights. During this time the Black Rage came upon him and he fought to suppress it. Calistarius' will stayed strong, however, and he emerged from the rubble as Mephiston, one of the most powerful psykers ever to bless the Emperor of Mankind's name.

His resurrection did not go unnoticed, however. As Mephiston heaved aside the massive boulders from his makeshift tomb, the sound of scraping stone drew the attention of a band of Orks still roaming the ruins. Coming upon the stricken Astartes, the Orks thought Mephiston appeared to be easy prey, as he was weaponless and his armour was in ruins. They soon came to rue their decision to attack the "helpless" Space Marine. Outmatched by Mephiston's speed, five Orks died within seconds as the Astartes rained down powerful blows upon them that pulverised flesh and shattered bone. Too stupid to realise that they were outmatched, the Orks pressed the attack. But the reborn Blood Angel continued to fight the brutal Orks until Mephiston punched a large hole clear through the chest of the largest Ork and ripped out his heart.

Under Lord Commander Cervan Dante Mephiston soon became the Chief Librarian of the Blood Angels, and Dante's right-hand man in governing the Chapter. He is one of only three known survivors of the Black Rage, having defeated its hold upon himself twice.

Lord of Death
Shortly after defeating the Black Rage, Mephiston's strength -- psychic, physical and martial -- surpassed those of almost all his Battle-Brothers, and he quickly rose to become the Chief Librarian of the Blood Angels, and was granted the title of "Lord of Death." His psychic powers are so great that few can surpass him, and no other member of the Astartes could best him. His skill in combat is comparable to the greatest of heroes that the Imperium of Man has ever known. Some say that a part of the true power of his Primarch runs through him since his defeat of the Black Rage, and he is indeed a true son of Sanguinius.

The Reborn Angel
Upon the world of Cybele, one of the most dire events in the Blood Angels' long history came to pass in the form of Brother Arkio, who possessed the sacred relic known as the Spear of Telesto, and proclaimed himself to be the reincarnation of Sanguinius. Fealty was given to the so-called "Reborn Angel" by many within the ranks of the Blood Angels' 6th Company. Unknown to the Blood Angels, an Ordo Hereticus Inquisitor named Remius Stele, a secret servant of the Ruinous Powers, manipulated the situation to cause a schism within the Chapter. After Gallio and Vode were both killed by Arkio's loyalists, Mephiston decided that he, not Dante, should go and deal with Arkio. He reasoned that since he was a psyker, he could detect the taint of Chaos upon Arkio and his followers. Mephiston arrived on the Blood Angels' Shrine World of Sabien to judge Arkio, and turned the powers of his formidable witch-sight upon him. He saw the carefully hidden seed of Chaos that Stele had planted inside Arkio and denounced the "Reborn Angel" as false and Inquisitor Stele as a Heretic. Mephiston then challenged Arkio to a duel but before it began, Arkio's biological brother Sergeant Rafen, a fellow Blood Angel, arrived and offered to challenge him instead. Rafen was one of the few Blood Angels of the 6th Company who had doubted the veracity of Arkio's supposed resurrection, keeping faith with the Emperor and their Primarch, and formally denounced his brother as false. Mephiston looked into Rafen's mind and saw that he had seen a vision of Sanguinius and that he was destined to fight Arkio. The Lord of Death allowed Rafen to take his place, and the two siblings dueled to the death. After Rafen wounded Arkio and Arkio fled, the corrupted Inquisitor Stele ordered the Loyalist Blood Angels and the warriors of the Reborn to attack Mephiston and his entourage. Eventually, Rafen emerged triumphant, impaling Arkio through the heart with the Spear of Telesto. Arkio died begging for his brother's forgiveness. After his siblings death, the true master behind the nefarious Chaos plot revealed himself -- Malfallax a Greater Daemon of Tzeentch. Malfallax and Inquisitor Stele had entered into a devil's bargain with Warmaster Garand of the traitorous Word Bearers Legion to turn the Blood Angels to Chaos by using Arkio as a false messiah. When Arkio was killed by his sibling Rafen, Stele attempted to summon Malfallax, intending to have the daemon possess his slave Ulan. Instead, Malfallax betrayed the Inquisitor and possessed his body, fully manifesting as a Lord of Change. Malfallax then attempted to cause the Blood Angels to succumb to the Black Rage, but was in turn banished by Rafen using the Spear of Telesto. By the time Rafen had defeated the Daemon Prince Malfallax, Mephiston's iron will had snapped, and he fell once more into the Black Rage. Rafen directed the power of the Spear of Telesto at Mephiston himself, breaking the hold of the curse upon the great Librarian for a second time.