John Grammaticus - The Alpha Legion Mission: Grammaticus was over a thousand standard years old and one of the Cabal's few human agents when he was asked, in the early 31st Millennium, just before the outbreak of the Horus Heresy, to convince the Primarch of the Alpha Legion, Alpharius Omegon, to meet with the Cabal.The organisation wanted to recruit the Legion in their war against Chaos -- a matter of some urgency due to the imminent corruption of Horus by the Dark Gods at the Temple of the Serpent Lodge on Davin. To this end, Grammaticus travelled to the rebellious planet of Nurth and infiltrated the Geno Five-Two Chiliad, an Imperial Army regiment serving with the 670th Expeditionary Fleet and tasked with subduing the rebels.The Imperial forces were being assisted in this campaign by the Alpha Legion. Grammaticus, who often borrowed identities from dead Imperial Army officers as needed in order to avert suspicion, used the guise of intelligence officer Konig Heniker to infiltrate the Imperial foothold on the world.Grammaticus finally succeeded in arranging a meeting between the manipulative Alpharius and the Cabal. However, Alpharius had used a "honey trap," the beautiful Rukhsana Saiid, an Uxor (officer of the command staff) of the Geno Five-Two Chiliad, to manipulate Grammaticus in order to gain the upper hand in his dealings with the Cabal and bargain with the enigmatic xenos from a position of strength.Alpharius followed Grammaticus' advice to abandon the field on the rebellious world of Nurth, which was shortly after consumed by a Black Cube, an ancient Chaos weapon of planetary destruction created eons before by the first intelligent races of the galaxy.Alpharius next brought his expeditionary fleet to the world of 42 Hydra Tertius, known to the Cabal as "Eolith," to meet with Grammaticus' masters. On Eolith, Alpharius and his twin Omegon saw the portion of the Acuity concerning the Horus Heresy that Grammaticus had already been made privy to; if Horus was allowed to win the Heresy, the fragment of nobility in his soul would eventually lead to extinction for the human race through the outbreak of a bloody civil war.The war between the victorious forces of Chaos would wipe out Mankind in only two to three generations. However, the destruction of the human race would also have the effect of wiping out the Dark Gods as well, as their own existence was heavily invested in the darker psychic emanations of humanity. In this way, Mankind's extinction would preserve the galaxy and bring an end to the threat posed by Chaos to all life.If the Emperor was successful and defeated Horus, technological and cultural stagnation would consume the Imperium. Unable to progress, within ten to twenty thousand Terran years, the forces of Chaos would ultimately consume the entire galaxy.Faced with this choice, Alpharius Omegon decided to take the radical path they thought the Emperor Himself would have chosen -- join the side of Chaos and aid Horus' victory in the hope of destroying Chaos once and for all. The start of the Horus Heresy was a scant 18 solar months away at that point.Having completed his mission, Grammaticus discovered that Rukhsana Saiid was a secret human operative of the Alpha Legion and had only pretended to love him to aid her masters in the XX Legion. His mission was successful, but Grammaticus was emotionally distraught after his love had proven to be a lie, and he found himself mired in despair because he believed himself responsible for setting in motion events that would render humanity extinct one way or the other.He walked out of an airlock on a Cabal spacecraft without a spacesuit, hoping to end his immortality once and for all. Unfortunately, Grammaticus quickly discovered that he truly was Perpetual.