Having forgotten much of his mortal existence, Gregorius' only form of remembering was writing down his nightmares that haunted him even in his day-sleep. Embraced by one of the Inconnu in the dying light of Rome, he discovered the secret chapel of Michael under the Hagia Sophia. There he had a sudden epiphany, showing him the great plan of God within the mosaics and knew – for a brief moment – absolute peace... only to have it torn away from him as the vision faded.
His sire returned and nurtured his madness, guiding his hate against Michael, who had inspired this vision but left nothing to understand. When he heard of the Dream of Constantinople, he pleaded to travel there to exact his revenge. His sire and the other Inconnu agreed.
In Constantinople, he won Michael's heart by performing tragedies that granted him influence and access to the higher echelons of the city. He used this influence to cripple the methuselah's sanity further and further. When Constantinople finally fell, the Inconnu had no further use for him and Gregorius was destroyed.