- “I? I am a monument to all your sins.”— Gravemind
The Gravemind (Inferi sententia, meaning "Thinking Dead"), is the final stage in the life cycle of the Flood and is the ultimate hivemind of the Flood. It is a near-omniscient creature with complete control over all Flood forms. A particular Gravemind is the secondary antagonist in Halo 2, and a main antagonist in Halo 3.
A Gravemind starts out as a Proto-Gravemind—a Flood form created by merging the bodies and biomass of numerous sentient life forms; some Flood forms may also be repurposed and merged into the Proto-Gravemind. 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 made up of thousands of bodies if using human-sized bodies as a measuring unit.
The Gravemind and its subordinate Flood infection will then continue to accumulate. Eventually, when the Flood infection has become too large for even the Gravemind to control—or when no life remains in the galaxy—the Flood infection will reach the Intergalactic Stage, and Flood will leave the galaxy with the intent to create a new Gravemind elsewhere.
Gravemind makes up a distributed intelligence, with a single primary consciousness made up of multiple, smaller instances that seem capable of acting independently. This is shown in Silentium, where the Precursor Gravemind compares itself with Catalog, a group of modified Forerunners networked together into single mind acting in concert with many others.
Due to the brevity of its mysterious appearances in Halo 2, little is known about the Gravemind's physical form. It is a massive Flood form whose "mouth" resembles a fleshy, multi-layered Venus Flytrap. The organ is used to speak and to exhale Flood Spores. The remainder of the Gravemind's body consists of a mass of enormous tentacles. During its time beneath Installation 05's Library, some of its tentacles grew to be miles long and stretched throughout the Installation.
The Gravemind, like the Proto-Gravemind from which it formed, is made of countless bodies and corpses; The Art of Halo states that Gravemind is "literally built from the bodies of its enemies and its own fallen warriors reassembled into a massive, tentacled, and intelligent entity." Gravemind references this fact often, often calling its current whereabouts an empty grave or burial mound—where there should be many graves, there is just the Gravemind. Even its name, "Gravemind," references this: it is the mind of the grave. The consciousness of the Gravemind is formed from the accumulated intelligence and memories of every Flood host ever consumed.
Gravemind is the controlling intelligence behind the parasitic Flood species. In this way, it appears similar to a puppeteer. 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 032 Mendicant Bias, it compared itself to the AI, describing it as "a single intelligence inhabiting multiple instances" and calling itself "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, its 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. It is widely believed that the Gravemind uses some form of telepathy to command its disparate Flood components.
The Gravemind is also able to subvert AIs. In the Forerunner-Flood war it was capable of altering every Forerunner AI's basic logical processes, causing it to aid the Flood cause. This 'Logic-Virus' was considered by the Forerunners to be the informational form of the Flood infection, to which Mendicant Bias was the first victim in its 43-year discourse with the Precursor Gravemind.
During the Flood-Forerunner War, when the Gravemind was a galaxy spanning network, it began assembling entire planetary ecosystems into enormous, highly complex structures referred to as 'Key Minds'. Each Key Mind was said to have easily matched a single Forerunner Metarch-level AI (By far the most powerful and intelligent grade of AI the Forerunners had developed and of which Mendicant Bias was an example) for strategic planning and raw computational power.
Due to the Gravemind's understanding and absorption of Precursor knowledge, it was capable of controlling and manipulating Precursor technology in the Forerunner-Flood conflict, which allowed it more effective slipspace technology and the ability to prevent Forerunners from using Slipspace. Now that all Precursor technology has been destroyed, it is unknown if the current iteration of Gravemind was capable of the same thing, though if all Flood contain all memories of the prior versions of Gravemind or they are otherwise stored somewhere, it could be surmised that it still retains this ability.
During the Forerunner-Flood war, the first known Gravemind came into existence as a centralized intelligence to coordinate Flood efforts against the Forerunners, formed from the minds of all the Sentients it had consumed and the Precursors which, in their insanity, found it to be a serendipitous emergence and began to guide and feed its growth. It is indicated that the remaining Precursors became the Flood fully, to a lesser or greater extent. Eventually Forerunner space navy tactics began to fail. The Forerunners developed the Halo Array as a desperate countermeasure before the war began fully, 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, but the Forerunners were reluctant to use it; the Master Builder instead abused his powers to have the San'Shyuum Homeworld annihilated.
However, the Flood were growing in number, and quickly were gaining ground across the Galaxy. Forerunner commanders realized that their naval tactics were being overcome, and a new solution was necessary if the Forerunners were to pull out of this "stalemate"; a Contender-class Artificial Intelligence, 032 Mendicant Bias, was crafted by the Forerunners to directly attack the Gravemind form and any surrounding Flood biomass in an effort to eliminate the central Flood consciousness. At least four installations, the Ark, Onyx Shield World, Requiem and an unnamed Shield World, were constructed by the Forerunners as shelters for themselves when the Halos fired.
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 proud as to deny the next step of biological 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. Convinced by the Gravemind's arguments, Mendicant Bias intentionally became rampant, developed a hatred for his creators and actively worked toward their destruction. The Gravemind utilized a 'Logic-Virus' to subvert other AIs, and may be how he converted Mendicant Bias to his cause originally.
The Gravemind continued to grow, growing enormous, planet-covering nodes of itself called Key-Minds that enhanced its raw computational power to such a degree that it began to completely overwhelm the Forerunners, forcing them into extremely pricey naval engagements that kept the Flood from winning for 300 years. Using knowledge of the Precursors to which it was born from and had become, the Gravemind used the Star Roads of the Precursors to attack the Forerunners, hampering their Slipspace capacity and utterly destroying their fleets, and marking the point at which Forerunner resistance had began to truly break down.
The Forerunners developed a new AI, Offensive Bias, which coordinated the final battle against Mendicant Bias and the Flood. The Gravemind was destroyed or stopped by the first activation of the Halo rings.
"Now the gate has been unlatched, headstones pushed aside! Corpses shift and offer room, a fate you must ABIDE!"
Following the Flood outbreak on Installation 05, the Gravemind rebuilt itself deep under the Library of the installation. During the Battle of Installation 05, the Gravemind was capable of utilizing Delta Halo's teleportation grid. After capturing John-117 and the Arbiter, the parasite 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, is able to tap into the teleportation grid although it is possible when the Gravemind captured 2401 Penitent Tangent, he absorbed the knowledge of how to access Halo's teleportation grid, just like Cortana on the first Halo when she was in the Control Center.
Gravemind later used the UNSC In Amber Clad 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.
In the wake of his successful takeover of High Charity, The Gravemind initially planned as his next move to attack and infest Earth. He was however forced to put this plan on hold when, through the knowledge of the assimilated Regret (and possibly Mercy), he learned about the Prophet of Truth's apocalyptic plans to use the Ark to remotely activate the entire Halo Array. Realizing the extent of the danger he faced, the Gravemind did not attack Earth directly but instead frantically used High Charity to make a Slipspace jump to the Ark and crash-land on the megastructure, though he did send the Indulgence of Conviction to Voi in an attempt to accomplish one of his original goals but it failed due to the intervention of the Master Chief, the Arbiter and the Sangheili fleet.
Unable to reach Truth on his own, the Gravemind briefly allied himself with John and the Arbiter to stop Truth from activating the rings; supplying them with an army of Flood Combat forms to help them take on Truth's remaining forces. The alliance however crumbled as soon as the battle was over with Truth's death; the Gravemind betrayed the Master Chief and the Arbiter the moment the crisis was averted and tried to assimilate them. 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, John infiltrated High Charity to retrieve Cortana, who has the Activation Index from the first Installation 04.
As John traveled deep into High Charity, he faced multiple Flood forms and heard the Gravemind taunt him, allowing 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 [John's] bones" if she didn't reveal the secret.
After John rescued Cortana, the Gravemind became enraged, realizing that she planned to use the incomplete Halo to destroy him. As John attempted to escape High Charity with a damaged Pelican, the Gravemind attempted to take him down, but was repulsed from the heat from its jets and presumably destroyed in the explosion. After traveling to Installation 08, however, John discovered that the Gravemind was attempting to rebuild himself on the new Halo. The Gravemind ultimately failed to stop John from activating the ring and destroying him, at least for the time being.
The Gravemind has an obscure and complex personality. When he was first seen by John-117 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.
In Halo 3, his personality undergoes a similar progression. Early on, he is shown to have a calm and collected personality, but once the activation of the Ark is prevented, the Gravemind bursts into a victorious, maniacal laugh, briefly boasting in iambic heptameter. In the following level, Cortana, a broader spectrum of his personality is asserted. He begins with his calm and collected voice, as well as a slightly confident tone. As John finds his way deeper into High Charity, however, the Gravemind becomes more irritated by his progress, and begins to shout at him. Once Cortana is rescued, the Gravemind begins to emit a series of mangled, animal-like roars, and speaks in an infuriated tone. In the final level of Halo 3, Flood Dispersal Pods crash onto Installation 08, and the Gravemind begins to speak again, this time in an angry yet confident tone.
The mostly collected and impassive tone that is frequently heard from it can be justified by his implied near omniscience; his knowledge of the present and ability to accurately predict the future means that he has little reason to worry about anything. He only becomes truly irritated or angry when an unforeseen event happens, or when there is something he doesn't know. Triggers for his anger include Cortana's secrets and John's ability to rescue her. When defeated, he shows sadness, not anger; it may be that he has become used to omniscience, and is only truly angered when he is wrong. This is supported by the fact that in the level Cortana, his tone quickly changed to confidence and almost amusement when he realized parts of John-117's objective (with phrases such as "Of course, you came for her! We exist together now. Two corpses in one grave").
He is also known to be quite manipulative: in Halo 2, Gravemind tricks John into being a decoy to distract the High Prophets as he attempts to take over High Charity, and in Halo 3, he helps John-117 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 032 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 is not violent when it doesn't benefit him; this is what makes a Gravemind a key stage in Flood evolution. Unlike the savage and single-mindedly bloodthirsty Combat and Pure Forms that precede and obey him, the Gravemind is able to analyze situations and avoid confrontation when it is necessary for the Flood's continued survival.
By the end of the game, the Gravemind gives a short monologue in a disheartened tone, cryptically admitting that he knows he can do nothing to stop his fate, which he believes was unjustly forced upon him. He says that the activation of Installation 08 will only add time "to a sentence [he] never deserve[d]". Considering it's original origin as the Precursors, this may indicate resentment that their creations would once again harm it, and a failure to understand why.
- The term "Gravemind" was coined by Bungie staff Jaime Greisemer.
- In several Forerunner data logs, the controlling intelligence of the Flood is referred to as a "Compound Mind."
- Originally, the Gravemind was meant to have skulls as teeth.
- The Gravemind frequently speaks in trochaic heptameter.
- 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.
- Three quotes from the Gravemind, "Two Corpses in One Grave", "A Monument to All Your Sins", and "This Is Not Your Grave", are also the titles of achievements in Halo: Reach.
- In Halo 4, one of the Flood medals is titled Gravemind.
- The Gravemind was designed by Robert McLees and Juan Ramirez.
Halo 2: Anniversary
- Halo 2 (First appearance)
- Halo 3
- Halo: Evolutions - Essential Tales of the Halo Universe
- Halo Legends
- Halo 5: Guardians (Mentioned only)
- Nikon.bungie.org - Determining the Real Sizes of Objects in Halo
- Halo 2 - Gravemind (level)
- High Charity, Cortana: "Flood controlled dropships are touching down all over the city! That creature beneath the Library, that 'Gravemind,' used us. We were just a diversion."
- Halo Encyclopedia
- Halo 3's, Terminal
- Bungie.net: Feast of Bones
- The Art of Halo, page 56-57
- Halo: Evolutions, Human Weakness