Octavian was a Bishop from Second Class who had deployed Dr River Song on a covert mission which led to her presence on the Byzantium, that housed one Weeping Angel. When he arrived with his clerics at the crash site of the Byzantium, he was displeased with River until she introduced the Doctor, the "equivalent of an army" she had apparently promised for assistance.
While discussing their plan of action, Octavian questioned Song whether she had informed the Doctor of her true identity.
He led his men into the Maze of the Dead below the Byzantium, three of whom were soon killed by the Angel. The Doctor assured him they could not have been saved, but Octavian reminded him that he would be the one to tell their families while he went off in his blue box. Nonetheless he still told the Doctor he had faith in him when they were surrounded by Angels. (DW: The Time of Angels)