John Grammaticus was an enigmatic human psyker who served as an agent of a xenos organization known as the Cabal in the latter days of the Great Crusade. Among the powers he wielded was the ability to understand and speak any language and identify where a speaker came from based on how they spoke; he claimed there was not a language that he could not master.[1a]
Grammaticus had been an officer of the Caucasian Levvies, a great army that had served under the Emperor during the Unification Wars on Terra. During a victory ceremony after defeating the forces of the Panpacific Empire, Grammaticus briefly met the Emperor, who recognized his psyker abilities and offered to speak further to "consider the options available to beings like us."[1b] Before they could have that meeting, Grammaticus was killed at Anatol Hive. The eldar Autarch Slau Dha brought Grammaticus back to life, gave him the ability to reincarnate, and put him into service in the Cabal.[1c]
Grammaticus once spent eighteen years in an insane asylum[2a].
A thousand years later, on the eve of the Heresy, the Cabal dispatched Grammaticus to suborn the Astartes Alpha Legion to their cause. The Cabal had foreseen the treason of Horus and the impending civil war that would result, and believed that the Alpha Legion and its primarch Alpharius had a great part to play in that coming war. To that end, Grammaticus infiltrated the Geno Five-Two Chiliad, an army in the 670th Expedition Fleet, under the guise of intelligence officer Konig Heniker. He also borrowed identities from other dead officers in order to avert suspicion.[1d]
Eventually, he came to the notice of Alpharius, who captured and questioned him of the Cabal and its intentions.[1e] After following Grammaticus's advice to abandon the field on Nurth, which was shortly after consumed by a Black Cube, Alpharius brought his fleet to 42 Hydra Tertius, known to the Cabal as "Eolith," to meet with Grammaticus's masters. In a carefully planned deception, Alpharius used Grammaticus to turn the tables on the Cabal, so that he could meet with them from a position of strength.[1f] Grammaticus had been shown what Alpharius and his twin, Omegon, would later see: if Horus was allowed to win the Heresy, the fragment of nobility in his soul would lead to Armageddon - a bloody civil war that would wipe out mankind in two to three generations. This would also wipe out the Dark Gods as well, as they were heavily invested in humanity, thus preserving the galaxy at the cost of the human species. But if the Emperor was successful, stagnation would grip the Imperium; within ten to twenty thousand years, Chaos would consume the entire galaxy.[1g]
As the Heresy spread to Calth, Jon contacted a former colleague there, Oll Persson, through a dream. Trying to convince him to help, Grammaticus showed him a vision of the final battle of the Heresy, Horus standing over Sanguinius's body[2a].
The Alpha Legion was set on its path to join with Horus. Believing that he had put into motion the extinction of his own species (or so he thought), Grammaticus threw himself out an airlock of a Cabal vessel, hoping that this death would be his last.[1h]
- 1: Legion (Novel) by Dan Abnett
- Know No Fear by Dan Abnett
- 2a: Target//Engagement, Chapter One