Prophet of Supposition
From Halopedia, the Halo wiki
In Conversations from the Universe, the Prophet of Supposition sends a letter to the High Council suggesting reasons for the Flood's appearance on Installation 04.
Nothing else in known about him, but, based on his attitude towards the Flood, it has been speculated that he, like Tano 'Inanraree, was a member of the Covenant fringe sect known as the Governors of Contrition.
