Menes Kalliston - Return to Prospero: Six solar months after the tragic events of the First Battle of Prospero, the sanctioned Imperial military reprisal against the Thousand Sons Legion's homeworld of Prospero,  Captain Menes Kalliston of the 4th Fellowship led a squad of battle-brothers to the ravaged surface of their homeworld to seek for any signs of survivors or their primarch.Instead, this squad was taken by surprise when they encountered a much larger force of Traitor World Eaters led by Assault Captain Khârn, equerry to his primarch Angron. The World Eaters were also on Prospero for their own nefarious reasons.In the ensuing conflagration, the majority of the Thousand Sons squad was killed, and an unconscious Kalliston was captured by Khârn. When Kalliston finally came to, he discovered that he had been shackled to a chair, his innate psychic abilities severely weakened. He was interrogated by an individual who remained in shadow.Catching furtive glimpses of his tormentor, through bleary eyes Kalliston thought he made out grey-coloured Power Armour, and assumed that his captor was one of the hated Space Wolves Astartes who had destroyed his homeworld. Kalliston's tormentor desired to know the Thousand Sons captain's purpose for returning to Prospero.Kalliston eventually realised that his tormentor's armour, which he had thought to be grey in the near-total dark, was actually a dirty white. The shoulder guards were once a bright blue colour, though every exposed surface on the battle-plate was covered by a translucent layer of brown-red filth. His captor was a War Hound of the XII Legion, or, as he believed they had started calling themselves, a World Eater. To Kalliston the new name was ludicrous, a perversion of everything the Legiones Astartes stood for.As Kalliston's clarity returned to him, he slowly realised that his interrogator stood on the brink of madness. As he scrutinised his tormentor further, he could make out a series of iron studs implanted under the flesh, further up on the scalp. These neural implants, colloquially known as the Butcher's Nails, had been forbidden by the Emperor to be used by Astartes and had been prohibited for good reason. They accelerated an Astartes' aggression and stoked it, amplifying an already testosterone-charged superhuman killer into a truly savage murderer.Kalliston realised he was in the presence of the savage Khârn, the captain of the World Eaters' 8th Assault Company and equerry to Angron himself. Withdrawing an iron pendant from his armour fashioned in the shape of a wolf's head howling against a crescent moon, Khârn explained to his captive that the World Eaters had come to Prospero on behalf of Horus to collect this item, known as the Moon Wolf.Once a part of the Warmaster's war plate, it had been used as part of a sorcerous ritual by the Thousands Sons' Primarch Magnus the Red to make contact with Horus, and could be used to do so again. But Kalliston quickly realised that there was another reason that the World Eater had come to Prospero, for Khârn seemed to burn with agony. An agony that could only be discharged by murder.Biding his time, Kalliston goaded Khârn into revealing his true intentions. As the Thousand Sons captain pressed the agitated World Eater for answers, his psychic powers slowly began to return to him. Kalliston attempted to manipulate the situation by subtly swaying Khârn with his words and his innate psychic abilities. Kalliston realised that the World Eater had come to Prospero seeking certain arcane devices that might be able help him find a cure for his affliction.Kalliston explained to Khârn that there was still time. For though the sorcerous devices once used by the Thousand Sons had all been destroyed, he possessed the necessary knowledge to replicate their functions. He could help heal the World Eater's broken mind, remove the neural implants and restore his ebbing Humanity. Kalliston could help take away the fire that drove him onwards, goading Khârn on to the acts of random violence and murder he abhorred.Kalliston knew that the World Eater was lost in a universe of pain, one that was only temporarily forgotten during the act of killing, a common affliction for those who fell to the corruption of the Blood God Khorne. He knew that his words had reached the sliver of Khârn's old self that still endured. But suddenly, the rage took over and Khârn snapped back to the reality of his painful existence.He attacked the Thousand Son captive with a roar, intent on rendering him limb from limb. Kalliston desperately called upon his remaining psychic reserves of power and managed to free himself from his bonds and launched a series of mental attacks against the enraged World Eaters officer. But it was all for naught, for the berserk Khârn possessed little of his remaining sanity and would not be persuaded by any means to stand aside from his intended kill.As Kalliston was being pummeled to death, he reflected that he had given Khârn every opportunity to choose his path, and that when the murder and madness had finally subsided, he would have the leisure to reflect on this choice -- he could have turned back. Kalliston foresaw that in the near future, Khârn would be uncontainable, and would turn on whatever force had sought to channel his rage for their own purposes. None would ever master him, for he had lost mastery over himself and become a true mortal embodiment of the Blood God's unending thirst for death.