House Vyridion was a Household of Imperial Knights that existed at the foundation of the Imperium of Man. Through treachery and to their ever-lasting shame, House Vyridion was led to break its vows of fealty to the Imperium and join the forces of the rebellious Warmaster Horus Lupercal. Yet, after their first battle alongside the Traitors, House Vyridion recognised the error they had made and broke all ties with their former allies in order to travel to Terra and ask for the Emperor's Pardon. Imprisoned, but later pardoned, House Vyridion was called upon by the Emperor's own bodyguard, the Legio Custodes, to fight alongside them in defence of the Imperial Webway Project in the dungeons of the Imperial Palace.