Raf Maven was a Knight of House Taranis who rode to war in the Great Crusade aboard the war-suit Equitos Bellum, and whose name would come to be inseparable from the very survival of the most ancient household of all. In his earlier service he was the close comrade of a fellow Taranis Noble, Leopold Cronus, and the two won considerable renown together upon the battlefields of the Emperor's expanding domain, bound by a friendship that would be tested to destruction in the years to come.
Maven's defining trials came amid the treachery of the Schism of Mars, when the followers of the Fabricator-General turned to the Warmaster Horus and plunged the Red Planet into civil war. In the days before the open slaughter, Maven and Cronus were among the Knights charged with defending the domains of the loyalist Magos Ipluvien Maximal, hunting down the feral servitors that had begun to gnaw at the Magos' reactors; under their old Preceptor, known as Old Stator, they ran the malfunctioning horrors to ground and destroyed them. It was in the course of such duties that Maven's auspex first registered a vast and unknown war machine abroad in the Martian wastes, its passage marked by a slaughtered mag-line train, and he and Cronus set out at once to hunt the thing down.
They ran it to earth at last within the tortured canyons of the Noctis Labyrinthus, where the machine stood poised to annihilate a column of Mechanicum servants. Working in concert, the two Knights brought down an avalanche of rock upon the engine, and Maven delivered the deathblow himself, driving the blade of Equitos Bellum deep into its hull. Yet the greater doom of the household was still to come. When the traitors moved against the loyalists in earnest, House Taranis rode to the defence of the Magma City, the great forge-hold of their ally Magos Koriel Zeth. There, alongside the god-engines of Legio Tempestus, the Knights made their last stand, breaking the Mortis engines of the enemy and helping to slay the traitor Ambassador Melgator, but at a price that beggared the household. Of all the Knights of Taranis, only Maven and Cronus are said to have walked away from that ruin.
Upon those two survivors the future of the eldest household now rested. Maven took up the title of Lord Commander and gave the remainder of his life to the painstaking labour of rebuilding what had been lost, gathering new scions, reconsecrating salvaged Thrones Mechanicum, and nursing the shattered lineage back toward strength. In memory of the kinsmen who had fallen at the Magma City, he ordered a new device added to the heraldry of the household, a mark of mourning and of oath that the reborn Taranis carries into battle to this day. From the near-extinction of the First House, Raf Maven forged its second life, and by his hand the oldest of all knightly lines endured into the long night of the Imperium.