The Sustenance

"The Sustenance" was a fragment of abstracted personality. "The Sustenance" was formed as a result of Mendicant's defection to the Flood, and imposed rampancy. Instead of forming a separate personality, however, the corrupted fragment had latched onto a primary shard of the AI's default personality. As long as "The Sustenance" had remained latched to a part of Mendicant's true personality core, it would continue to reason ways to justify that he had made the proper decision by defecting, due to a deep-rooted sense of self-denial for siding with the Flood. This fragment was the one whom had made it to the Ark, and then to the Forerunner Dreadnaught, which had then been transfered to the San 'Shyuum homeworld. Eventually, "The Sustenance" found itself installed into the Covenant's High Charity, where it was referred to as "The Oracle", and served as a primary basis for their religion.

It had performed its task until the fateful day that it had simply run out of excuses, in which its program had inevitably crashed. Upon Mendicant Bias losing his sense of morality for his ancient judgment, the AI concluded that its actions against the Forerunner had been mistaken. At this point, the remaining personality had redeemed it's sense of reality, and had become metastable, regardless of it's true form having been compromised. At this point, the AI would rebel against the the Covenant Empire and assist the Spartan-II Master Chief, John-117 fulfill his goal and survive. By succeeding in this, he would achieve piece-of-mind, being able to prove to the Forerunner, even if only in his head, that he had returned to reality, and seeks penance for his irreversible actions.

History
In order to prevent Mendicant Bias from subverting or harming him, Offensive Bias had shattered of Mendicant Bias into its component sections and scattered them throughout the few remaining ships of his fleet for transport to Installation 00, where he would study the fallen AI construct. "The Sustenance" was a suiting title for one of the shards that Mendicant Bias' disillusioned mind had been compromised of. Unbeknownst to Offensive Bias, this fragment was actually latched onto Mendicant Bias' true sentience.