Lord Numetor of the 8th Company

Not much is known of his early years as Adeptus Astartes, but he seem to have a rivalry with Marneus Calgar that comes before Calgar became Chapter Master. Nobody (maybe not even them) know how it started and why it escalated so quickly, but the last years saw Calgar and Numetor disagreeing to the point of turning this rivalry into open hate. 

Numetor accuses Calgar of putting them into a reserve Company for envy of his battle skills, and says that Macragge just ignore all reports, pleads and documentations the 8th Company sends, not daring to answer not even when Numetor found a lost stash of chapter relics inside an undisclosed asteroid. Calgar in his turn, accuses Numetor of being hot-headed, rude and unruly, and deny receiving any communication from the 8th Company at all in the last decades. 

Recently, Numetor open defiance against the Ultramarines hierarchy and his exotic interpretation of the Codex Astartes attracted many discontent Astartes to his side, and some dire violations of the Codex had been enacted by the captain. Rumors inside his flagship, Gladius Imperius, state that he wants to defect from Macragge and, perhaps, try to start a new chapter, with or without aid or support of the Inquisition and the High Lords of Terra... 

Even darker rumors tell about Numetor and some Adeptus Mechanicus Magus making heretic experiences with the geneseed, and the recent alliance between the captain and a radical Inquisitor, commanding a small host of Deathwatch marines, just open space for more and more sinister speculations...