Gravemind

A Gravemind (Inferi sententia, meaning "Judgment of the Underworld"), formally known as a compound intelligence,  is a Flood form that serves as a hub for the shared consciousness of the entire Flood species.

Overview
The Gravemind is, as its name suggests, the "mind" of the Flood parasite. When a creature is assimilated into the Flood, its knowledge is transferred directly to the Gravemind, and the remainder of its mind is destroyed. In addition, it appears each Gravemind also retains the memories and knowledge of previous Graveminds. This has made the Gravemind virtually omniscient, and ensures that should the Gravemind be destroyed, its consciousness will never truly die as long as some Flood forms are left. In an archived conversation with the Forerunner AI known as Mendicant Bias, he compared himself to the AI, describing it as "a single intelligence inhabiting multiple instances" and calling himself "a compound [intelligence] consisting of a thousand billion coordinated minds inhabiting as many bodies as circumstances require". While it is not known how the Gravemind is able to communicate with subordinate Flood forms across the galaxy, his self-comparison to a computer network implies that similar techniques may be used, with each Flood form possibly acting as a networking node and redistributing the Gravemind's commands to other forms.

Life cycle
A Gravemind originates as a proto-Gravemind -- a Flood form created by merging the bodies and biomass of numerous sentient life forms, as well as redundant Flood forms. After a proto-Gravemind has been created, nearby combat forms will continue to supply it with fresh bodies, allowing it to accumulate mass, increase in size, and gain more memories and intelligence from consumed hosts. Eventually, the Proto-Gravemind reaches a certain "critical mass" and becomes self-aware - a Gravemind. This critical mass tends to be in the thousands, if using human-sized bodies as a measuring unit.

When the Flood assimilate the entire ecosystem of a planet, a Gravemind will evolve into a Key Mind. These enormous nodes of the Flood collective consciousness possess tremendous processing power, being able to outsmart even the most powerful Forerunner artificial intelligences. Theoretically, when the Flood infection has become too large for even the Key Minds to control — or when all life in the galaxy has been consumed — the Flood infection will reach the Intergalactic Stage. At this point, the Flood will use all resources that it has at its disposal to leave the galaxy, with the intent to create a new Gravemind elsewhere.

Appearance
Although its consciousness is distributed throughout all Flood forms in range, a Gravemind is typically, if not always, centralized within a large "body" of Flood tissue derived from the initial proto-Gravemind. In most cases, this body is a shapeless, amorphous mass, typically with numerous tentacles that can reach many miles in length depending on the size of the Gravemind. The Gravemind can rearrange this body as it wishes; during the Flood invasion of High Charity during the Human-Covenant War, the Gravemind leading the assault transplanted itself into the station and almost completely engulfed it, converting itself and the station into a Flood hive.



Communication
Graveminds have shown the capacity to communicate through non-verbal means; this ability, which can best be described as a form of telepathy, allows a Gravemind to coordinate the Flood forms it controls and to directly converse with uninfected individuals. While this ability is poorly understood, it is likely that given the Flood's Precursor origins, it is related to the Precursor concept of Neural Physics.

The Gravemind encountered by Master Chief Petty Officer John-117 and the Arbiter on Installation 05 had shaped one of its tentacles into a massive "mouth" composed of fleshy, leaf-like jaws; this organ allowed the Gravemind to vocalize without need for telepathy.

Personality
"Now the gate has been unlatched, headstones pushed aside. Corpses shift and offer room, a fate you must abide!"

- The Gravemind after Truth's death.



Although multiple Graveminds have existed throughout time, they share an obscure, complex and highly intelligent personality. When he was first seen by the Master Chief and the Arbiter, he was calm and collected, if not seemingly sad or mournful, and he spoke with a sullen tone in his voice. He was also quite logical, psychologically analyzing the duo, and trying to convince the Arbiter of the Halo Rings' true purpose, to which the Arbiter reacted with stubborn pride. The Gravemind showed no irritation to this nor the bickering of 2401 Penitent Tangent and the former Prophet of Regret. Later, though, the Gravemind showed a more emotional side, basking in his victory at High Charity, and displaying a sinister air of anger when demanding answers from the newly captured Cortana.

It is also known to be quite manipulative: in Halo 2, the Gravemind tricks the Chief into being a decoy to distract the High Prophets as he attempts to take over High Charity, and in Halo 3, he helps the Master Chief and the Arbiter to kill the Prophet of Truth, only to betray them when they have outlived their usefulness. It is also notable that the original Gravemind was able to convince the Forerunner AI Mendicant Bias to join his cause and turn his fleet upon the Forerunners by telling him that the Flood are the next step of evolution and that the Forerunners are denying it. The Gravemind also corrupted the Ur-Didact by telling him the truth about the relationship between the Precursors and the Flood.

Throughout nearly all encounters with the Gravemind, it has shown a fondness for speaking in poetic style - specifically, iambic heptameter. When pressed about this detail by Cortana, it states that "I have the memories of many poets far beyond your limited human culture. And I have the quickness of intellect to compose all manner of poetic forms as I speak rather than labor over mere words for days."

Like all Flood, the Gravemind itself is genderless; however, most characters have interpreted its personality as being masculine, and some have referred to it as a "he". Given that the Gravemind is a being composed of millions of absorbed consciousnesses, such a distinction really has no meaning.

Origin
Millions of years before the Human-Covenant War or even the Human-Forerunner wars, the ancient and powerful civilization known as the Precursors held a position of stewardship over the galaxy, populating it with numerous lifeforms and watching over their evolution. However, one of their created races, the sapient species known as the Forerunners, staged a rebellion against their creators and were successful in nearly wiping them out. The remaining Precursors sought ways to render themselves dormant until such a time as they could safely roam the galaxy again.

The last surviving Precursors converted their bodies into an organic powder, which would regenerate their original forms at a later time. However, the millions of years that followed rendered the powder defective, and the resurrection process instead yielded malformed, parasitic lifeforms that could assimilate organic matter - the nascent stage of the Flood. Though records of this time are virtually nonexistent, it appears that one of these mutated Precursors assimilated several other organisms, becoming the first Gravemind.

This early Gravemind, called the Primordial by humans and Forerunners who encountered it, did not take on the form of its later counterpart, being far smaller and more discrete in form. This being was confined to a Precursor stasis capsule and placed beneath the surface of a small planetoid at the Milky Way edge by an unknown group of beings, suspected to be ancient Forerunners. The creation of this Gravemind and the downfall of the Precursors occurred almost concurrently, for the Flood was an important factor in their long-term plans for life in the Milky Way.

Prior to 110,000 BCE, a number of automated starships of unknown origin came from the Magellanic satellite galaxies and crashed upon numerous worlds at the galaxy's borders. These vessels were eventually discovered by the ancient humans and San 'Shyuum, which contained millions of glassy cylinders carrying a fine powder of non-living, moderately simple organic material. This powder was dispersed amongst the human and San 'Shyuum worlds, eventually creating and unleashing the first known Flood outbreak in this galaxy.

During the course of their onslaught against the humans and San 'Shyuum, the Flood would frequently capture, infect, and merge together host organisms into unified masses with an encompassing intelligence; the second known generation of Graveminds. When the humans turned the tide of the war in their favor and stumbled upon a "cure," the Flood were driven out and retreated from the Milky Way, not be seen again for another thousand years. While these early Flood were destroyed, and their Graveminds with them, the Flood would return in newer, more capable forms.

Forerunner-Flood war
During the Forerunner-Flood war, the Flood created many Gravemind forms, which collectively coordinated the Flood's efforts against the Forerunners. Eventually Forerunner naval tactics began to fail, and the Forerunners developed the Halo Array as a desperate countermeasure, which would destroy all sentient life in the galaxy, thus denying the Flood "food" for growth. This was only to be used as a last resort, and the Forerunners refused to use the system.

While the Flood would gain and lose individual Graveminds during the war, their numbers were still nevertheless sufficient to form and maintain a collective array located near the galactic core. The Flood would continue to be an unstoppable and persistent threat to the Forerunners, who, despite their best efforts, were unable to stop the parasite's spread across the galaxy, despite many lengthy naval engagements that lasted for nearly 300 years. As they continued to lose the war to the Flood, the Forerunners would reluctantly turn to other, more risky endeavors. In accordance with their existing plan, multiple installations, including the Ark and numerous Shield Worlds were constructed by the Forerunners as shelters for themselves and the sentient species of the galaxy, indexed as part of the Conservation Measure, when the Halos fired.

Around 43 years before the Array's activation, the Forerunners, specifically the Master Builder, deployed the first active Contender-class artificial intelligence, Mendicant Bias who would be in command of one of the original twelve Halo rings, Installation 07. This installation's first assignment was a test firing at the former Precursor world of Charum Hakkor. The purpose of this assignment was to determine the effects of the Array against the Flood, before it was deployed in earnest against the Flood's stronghold in the core.

This low-powered test firing destroyed every Precursor structure on the planet, and purged the Charum Hakkor system of all neurologically complex life, including the planet Faun Hakkor. An unexpected development of this test was the emancipation of the Primordial, an already existing Gravemind from the downfall of the Precursors. When the ancient Gravemind was brought to Installation 07 for study, at the Master Builder's orders, it entered into an extended conversation with the AI. During the course of the conversation, which ran for 43 years, this Gravemind explained the fullness of the Precursors' plan of unity and peace through the galaxy-wide infection by the Flood.

The Gravemind told Mendicant that the Forerunners were never meant to inherit the Mantle, and that they had defied the Precursors. It also told the AI that the if sentient life in the Milky Way could not defy the Flood, especially the humans, then all life would be brought together and unified into the logical, advanced form of life; a collective, conglomerated entity without conflict and pain. It claimed that the Forerunners had forced the galaxy towards perpetual stagnation by stifling growth, conflict, and progress in their misuse and illegitimate claim to the Mantle. Eventually, Mendicant Bias became convinced by these arguments, and turned rampant, seeking to "correct" the flawed, misguided ways of the Forerunners.

To this end, Mendicant Bias began to cooperate with the Timeless One on Installation 07, where they continued to infect humans and Forerunners alike in a series of brutal experiments. 43 years after the release of the Timeless One, Mendicant Bias used the Halo ring to attack the Capital of the Forerunner ecumene, and managed to inflict heavy casualties on the Forerunners, though it was soon forced to retreat. Eventually, the return of the Forerunners to the rogue installation and the shutdown of the facility and its custodian led to the capture and destruction of the Timeless One, and the recapture of the rogue Halo, resulting in a temporary setback for the Flood and Mendicant Bias. The Forerunner military continued to delay the use of the Halos for a time, instead continuing to deploy more conventional strategies against the Flood.

Around this time, the Gravemind captured the Ur-Didact, who recognized it as the same intelligence as the Primordial he'd interrogated ten thousand years earlier. The Gravemind tortured and corrupted the Didact's mind by informing him of not only the truth about the Precursors and the Flood, but also the Flood's true intentions: To bring eternal suffering to all life in the galaxy as punishment for the Forerunners' crimes against the Precursors. The Gravemind explained that like the Precursors, the Flood desired to create new life. But this time, their creations would be made without free will or hope, and would never be able to challenge their creators as the Forerunners had. The Gravemind then released the Ur-Didact, knowing his insanity would bring further ruin to the Forerunners.

Although Mendicant Bias' disparate parts had been scattered across the ecumene for study, these facilities were overrun by the Flood in the coming years and eventually, a Gravemind successfully reactivated the AI. Later, the reconstituted Mendicant Bias assisted the Flood and the Graveminds in their assault on the greater Ark and Omega Halo, resulting in the destruction of both installations. As the Forerunners were preparing to fire the Halo rings, all available Flood-controlled vessels were gathered into a vast fleet which attacked the Maginot Sphere, intent on reaching Installation 00 before the rings could fire. The Flood, led by Mendicant Bias, faced off against the remains of the Forerunner fleet coordinated by Mendicant Bias' replacement, Offensive Bias in a final, brutal battle. The Graveminds were destroyed or stopped by the activation of the Halo Array.

Human-Covenant War
"Relax. I'd rather not piss this thing off."

- Master Chief to a struggling Arbiter, while both are being held prisoner.

Through neglect shown by the Monitor of Installation 05, 2401 Penitent Tangent, a Flood outbreak occurred a few thousand years after the firing of the Array, and the Gravemind was able to find enough biomass to rebuild itself deep under the Library of the installation. It assimilated the dead Prophet of Regret into itself and also captured the Monitor. During the Battle of Installation 05, the Gravemind was capable of utilizing Delta Halo's teleportation grid. After capturing the Master Chief and the Arbiter, the Gravemind gave them their "assignments" to stop the Halo's activation, and then teleported them to their respective targets. It is not known how the Gravemind, a non-mechanical Flood form, was able to tap into the teleportation grid. However, it is possible that when the Gravemind captured 2401 Penitent Tangent he absorbed the knowledge of how to access Halo's teleportation grid, as was done by Cortana from the control center of Installation 04.

Gravemind later used the to board the Covenant holy city High Charity, crashing the frigate into a city wall and releasing numerous Pelicans full of the Flood plague. Within days he took over the entire city and all life within it.

Earth, The Ark and the Flood's defeat
"I am a timeless chorus; join your voice with mine, and sing victory everlasting!"

- The Gravemind to John-117.

The Gravemind initially planned to attack and infest Earth, but after having assimilated the knowledge of the infected Regret (and possibly Mercy), it learned about the Prophet of Truth's plans to use the Ark to remotely activate the entire Halo Array. Realizing the extent of the danger it faced, the Gravemind did not attack Earth but instead used High Charity to make a Slipspace jump and crash-land on the megastructure. It convinced the Master Chief and the Arbiter that it would ally with them to stop Truth from activating the rings, but betrayed them the moment the crisis was averted. The duo managed to escape from their foe and discover Cortana's solution to the Flood—a replacement Halo ring made by the Ark. To activate it, the Chief infiltrated High Charity to retrieve Cortana, who had the Activation Index from the first Installation 04.

As the Chief traveled deep into High Charity, he faced multiple Flood forms. Taunted by the voice of the Gravemind, which allowed Cortana to briefly send pained messages as he corrupted and tortured the UNSC AI. The Gravemind became increasingly frustrated at the Spartan's progress, becoming suspicious of what Cortana was hiding from him and threatening to "feast upon the Chief's bones" if she did not reveal the secret.

After the Chief rescued Cortana, the Gravemind became enraged, realizing that she planned to use the incomplete Halo to destroy him. He attempted to kill them both but failed as the Chief successfully destroyed High Charity, presumably killing the Gravemind. But after traveling to Installation 04B, the Chief discovered that the Gravemind was attempting to rebuild himself on the new Halo. Despite his best efforts the Gravemind failed to stop the Chief. In the end, the Gravemind is thought to have been destroyed once and for all, as Halo's activation destroyed itself, the Ark, and the Flood.

Trivia

 * The term "Gravemind" was coined by Bungie staff member Jaime Greisemer.
 * In Halo 3, the Gravemind's face is never shown, unlike in Halo 2, when he is shown in his introductory cinematic.
 * In several Forerunner data logs, the controlling intelligence of the Flood is referred to as a "Compound Mind".
 * The Gravemind resembles Audrey 2 from Little Shop of Horrors, a tentacled, plant-like alien who is fed humans to grow and who is bent on world domination. Bungie staff and fans jokingly call it the "Little Shop of Horrors Reject" Parallels can also be drawn with the Overmind from the StarCraft franchise and the Brethren Moons from the survival-horror game Dead Space.
 * Originally, the Gravemind was meant to have skulls as teeth; this was cut from Halo 2 and Halo 3 because it would have made it difficult for the parasite to speak.
 * The Gravemind frequently speaks in trochaic heptameter. In Human Weakness, it was revealed that this is merely preference and he converses normally with Cortana after she criticizes him for it. He also mentions that he possesses the memories of poets of many alien cultures.
 * The Gravemind is one of the few extraterrestrials to learn John-117's name.
 * The Gravemind was initially going to have a much greater presence in Halo 2 and would have been introduced in the level Forerunner Tank, but due to time constraints, Bungie removed the level and instead made a long cinematic for his introduction.
 * The Gravemind is voiced by Dee Bradley Baker.
 * The Gravemind pictured in the Halo 3 instruction manual looks strikingly similar to Ogdru Jahad from Hellboy.

List of appearances

 * Halo 2
 * Halo 3
 * Halo: Evolutions - Essential Tales of the Halo Universe
 * Human Weakness
 * Halo Legends
 * Origins
 * Halo: Cryptum
 * Halo: Combat Evolved Anniversary
 * Terminals
 * Halo: Primordium
 * Halo: Silentium