Tylos Rubio - Battle of Calth: After arriving in the Sol System with the terrible news of the Warmaster's betrayal, Garro, his fellow Death Guard Astartes and a number of other Loyalist refugees, were all placed in a fortress on Luna that belonged to the Sisters of Silence whilst the Emperor determined whether they were truthful or were simply further pawns of the Chaos Gods. Garro was eventually approached by Malcador the Sigillite, the acting Regent of Terra, who told him that the Emperor needed men like him to help form a new Imperial organisation outside the boundaries of the existing Imperial bureaucracy. Under the Sigillite's own seal, Garro was tasked with finding 7 other Loyalist Astartes from amongst both the Loyalist and Traitor Legions who were utterly devoted to the Emperor and his Imperium in body and soul. These Space Marines would eventually form the core of what would later evolve into the Grey Knights Chapter of Astartes, the Chamber Militant of the Inquisition's Ordo Malleus.Garro’s first mission was to war-torn Calth, a battle-scarred Agri-World located in the Veridian System. The Loyalist XIIIth Legion, the Ultramarines, were engaged against their treacherous former brethren from the XVIIth Legion, the Word Bearers, in a great contest of the Heresy known to history as the Battle of Calth. Garro slipped past the Word Bearers’ orbiting fleet and down to the surface of the war-ravaged planet. He was looking for the Ultramarines' 21st Company, under the command of Captain Erikon Gaius. During his mission for the Sigillite, when questioned as to which Legion he belonged to, Garro consistently referred to himself as a "Knight Errant" and the member of a "Legion of One." The 21st Company had been last sighted on the western outskirts of the city of Numinus. They had been at the forefront of the first Word Bearers assault and it had been their burden to witness the deaths of too many of their Battle-Brothers at the hands of the Traitors and their daemonic allies. They were now a company in name only. Their Captain had managed to rally them in the face of the brutal losses. With words and deeds he had led them into the fray, and they claimed back in blood a steep price from the Traitors, but not enough. They were cut off from their kinsmen, holding one of the mag-lev railroad approaches to Numinus City.Garro sought out Battle-Brother Tylos Rubio amongst the Astartes of the 21st Company, an extremely powerful psyker who had once been a Codicier of the XIII Legion before the Emperor's formal decree at the Council of Nikaea had banned the Space Marine Legions' use of psykers, including their corps of Librarians. Captain Gaius had been killed in a Word Bearers' assault when a large force of Traitor Marines and Chaos Cultists nearly overwhelmed the 21st Company’s battle lines.Garro arrived before the next assault and found Brother Rubio. He explained to the perplexed Ultramarine that he was there on the orders of Malcador the Sigillite and that Rubio must come away with him. Rubio refused to leave his Battle-Brothers in the face of annihilation unless so ordered by the Emperor himself. Much to Rubio’s surprise, the honourable Garro respected his decision and agreed to stand and fight with him against the Word Bearers.In the final assault, the Ultramarines were driven back in the face of overwhelming numbers, and sought cover within a cave. They were hard-pressed by the elite Word Bearers' Cataphractii armoured Terminators. Brother Rubio was sorely tested, and forced to restrain himself by his sacred oaths to the Emperor from using his innate psychic abilities, even though he knew that by doing so he could have saved the lives of many of his fallen Battle-Brothers. Facing imminent death, Rubio felt that he had no other choice and unleashed a powerful psychic attack, driving the enemy back with the full force of his powers. The tunnel collapsed in the process, burying the attacking Word Bearers Cataphractii Terminators under tons of rubble.The survivors of the 21st Company had been saved and the sole passage to Numinus had been denied to the enemy. Yet using his powers had cost Rubio dearly -- his honour before his Primarch and his Emperor. Garro told him to be grateful that he had saved his Battle-Brothers' lives. As he approached his fellow Ultramarines, they averted their eyes and as one turned their backs, shunning him.Rubio had disobeyed a Decree Absolute of the Emperor, and for that, there was no forgiveness. Garro drew his Power Sword Libertas and Rubio spun at the sound of it, fixing Garro with a furious glare. Garro held the sword out, the point down towards the ground. He had Rubio place his hand upon the blade to take an Oath of Moment, to dedicate himself to the orders of the Regent of Terra and put aside all other claims upon his honour. Rubio swore upon the blade, for he had little other choice, and became one of the Sigillite's primary agents, the Knights-Errant.