Mendicant Bias

"And so here at the end of my life, I do once again betray a former master. The path ahead is fraught with peril. But I will do all I can to keep it stable - keep you safe. I'm not so foolish to think this will absolve me of my sins. One life hardly balances billions."

- Mendicant Bias at the last Terminal of Halo 3

05-032 Mendicant Bias was a Contender-class Forerunner AI. He was the most advanced Forerunner AI at the time of his creation, and was charged with organizing Forerunner defense against the Flood before his defection to the Gravemind, who ultimately caused him to become rampant, and turn against his creators.

Beginnings
Mendicant Bias was tasked with resisting the Flood by studying and exploiting the weaknesses of the first Gravemind, or Compound Mind. At some point, the Gravemind contacted Mendicant Bias and convinced him to abandon the Forerunners and join the Flood cause, convincing him that the Forerunners were so gluttonous and prideful as to deny the next step of evolution: the Flood. The Gravemind insinuated that by clinging to the legend of the Mantle, the Forerunners had doomed the galaxy to eternal stagnation; the only way for the galaxy to progress was for superior beings to "restart" it. These superior beings, unsurprisingly, took the form of Compound Minds such as Gravemind and Mendicant Bias himself. Although the 43-year long conversation logs between Mendicant Bias and the Gravemind were sent back to the Forerunners, they believe that Mendicant would automatically fulfill its objective and destroy the Gravemind, and so did not intervene. Convinced by the Gravemind's arguments, Mendicant Bias intentionally became rampant, developed a hatred for his creators and actively worked toward their destruction. This was later mentioned by the Halo trilogy Gravemind in the short story Human Weakness from Halo Evolutions.

Fall from Grace
"What has taken you millennia to create, I erase in seconds."

- Rampant Mendicant Bias

The now rampant Mendicant then attacked with a fleet of over five million ships and completely obliterated the Maginot Sphere, and forced the Forerunners to accelerate work on their doomsday weapons. In order to give them time to complete the Halos' work, the Forerunners created another AI, Offensive Bias, to slow Mendicant Bias' advance. Offensive Bias lacked Mendicant's creativity, and possibly his free will, but was more methodically lethal. His only purpose was to prevent Mendicant Bias from accessing the Ark, and buying time to activate the Halo Array.

It seems that Mendicant Bias was unable to disable the Halos directly, perhaps not knowing their locations, and so the only chance he had to stop the coming cataclysm was to secure the Ark and stop the firing sequence from there. While he did not know the location of the Ark, he was aware of a method to reach it via the Portal and Key Ships. The Forerunners subsequently destroyed or disabled most of the keyships to stall Mendicant's assault. However, Mendicant Bias managed to locate (or thought he had located) one of the remaining keyships that led to the final, titanic naval battle with Offensive Bias. Mendicant's fatal mistake was that he had come to hold the Forerunners in abject contempt — his rampancy clouded his perceptions, such that he failed to anticipate the possibility of facing another AI. The Halos were then fired and ultimately, Mendicant Bias was outsmarted and defeated by Offensive Bias who used the now crewless ships as explosive triggers.

Repentance and Redemption
"For eons I have watched. Listened to you misinterpret. This is not reclamation, this is reclaimer."

- Mendicant Bias revealing the Covenant's error.

"I will reject my bias and make amends... My makers are my masters. I will bring them safely to the Ark"

- Mendicant Bias declaring its penance.

Offensive Bias intended to bring the vanquished Mendicant Bias to Installation 00 for study. In order to prevent Mendicant from subverting or harming him, Offensive Bias broke the Compound Mind of Mendicant Bias into its component sections and scattered them throughout the few remaining ships of his fleet for transport. Only a part of Mendicant made it to the Ark. One shard of Mendicant Bias' personality construct array was left on a Forerunner Dreadnought and lost. The ship was later found by the Covenant and installed in High Charity. Mendicant Bias' presence was known to the Covenant and it was regarded as an Oracle.

In 2525, it was consulted, or rather "interrogated," by the Minister of Fortitude and the Vice Minister of Tranquility concerning the large number of Forerunner artifacts or "Holy Relics" on Harvest. In a shocking revelation Mendicant Bias revealed that the "Holy Relics" were actually humans and that the Covenant faith was based on an age-old mistranslation. The glyph on the Luminary was mistaken as "reclamation" when it truly meant "reclaimer". This had the potential to completely undermine the Covenant's unity and faith. A political revolution ensued to prevent this and, ultimately, led to the Human-Covenant War.

The AI seems to have concluded that its ancient actions against the Forerunner had been mistaken and announced to its Covenant hosts its intention to bring the "reclaimers" to the Ark. To this end it attempted to leave High Charity by launching the dreadnought, an act that would have seriously damaged High Charity. Mendicant Bias was foiled only by chance; it was disconnected by some Lekgolo worms wriggling inside the ship. The AI was more formally disconnected afterward to prevent it from commandeering the ship again.

During the First Battle of High Charity in 2552, the UNSC AI Cortana fought Mendicant Bias to delay the launching of the dreadnought, allowing Master Chief to board and return to Earth. In the proceeding events Mendicant Bias was carried through the Voi Portal to Installation 00, where the missing shard was finally reunited with the part that resided in the Ark's systems. On the Ark, it attempted to communicate with Master Chief through Terminals, claiming it sought atonement by helping the Spartan. Exactly what form that assistance took is uncertain.

"And so here at the end of my life, I do once again betray a former master. The path ahead is fraught with peril. But I will do all I can to keep it stable - keep you safe. I'm not so foolish to think this will absolve me of my sins. One life hardly balances billions. But I would have my masters know that I have changed. And you shall be my example."

- Mendicant Bias to John-117.

This reclaimed sanity seems to suggest that some AIs might be sophisticated enough to come back from rampancy, like Mendicant Bias and Cortana have. It may also have reached meta-stability, where an AI can be said to have a conscience equal to that of a sentient being.

Trivia

 * Mendicant Bias has been connected and coupled with the whispering voice heard distinctly in the Mausoleum Suite on the Halo 2 Original Soundtrack. Certainly, there are similarities between the character expressed in the whispers and Mendicant Bias — both are imprisoned by memories of their past crimes, both are seeking forgiveness, and both retain a sense of fatalist philosophy.
 * It's possible Cortana learned about the Ark and its purpose from Mendicant Bias, when she tried to delay the Dreadnought's launch sequence.
 * You can read the shard of Mendicant Bias' personality that made it to the Ark by accessing all the terminals and getting the Marathon Man achievement.
 * The meaning of Mendicant Bias' name is unclear. Mendicant comes from the Latin Mendicans and describes those, particularly from religious orders, who survive purely on charity and begging. Bias is a preference to a particular perspective or ideology. One possible meaning is that he survived purely on Offensive Bias's charity, and he shows obvious bias to The Flood.
 * Fans have speculated Mendicant Bias can also be heard as a whisper during the Terminals' shift, or the script change from the original terminal messages to the later messages after the originals become red. If you listen to the terminals shifting and play it backwards, you can hear a voice, most likely Mendicant Bias.
 * The actions of Mendicant Bias are similar to that of the Artificial Intelligence from Marathon's Durandal.
 * Mendicant Bias is possibly the "brother" that Adjutant Reflex was talking about and was later absorbed by, there is evidence of this in MB's picture: the symbol in the left hand side is similar to Adjutant Reflex's third Bungie.net avatar.

Internal

 * Iris
 * Adjutant Reflex
 * Offensive Bias