Flood

The **Flood**, designated as **LF.Xx.3273** by the Forerunners (Latin ***Inferi redivivus*** meaning "the dead reincarnated") is a species of highly virulent parasitic organisms that reproduce and spread by consuming other lifeforms of sufficient biomass and assimilating them as part of their collective consciousness; the Flood is all that remains of the ancient race known as the **Precursors**, and are the greatest threat to the existence of life (or more accurately, biodiversity) in the known universe.

## History

### Prehistoric history

#### Arrival

The Precursors originated outside the known universe, their accumulated knowledge extending back through the Domain, their higher-dimensional reservoir, at least 500 billion years. They first arrived in the known universe billions of years ago, when the very oldest galaxies began forming. Exploring the nascent cosmos, the Precursors found it void of any life; to remedy this, they went about setting in motion the events which would eventually lead to the genesis of life in various galaxies. In setting the stage for these new forms of life, the Precursors intended to eventually create the ultimate lifeform, a completely harmonious and selfless entity which would perfectly encapsulate their philosophy of Living Time.

Not long after the Precursors began their grand experiment, the Q arrived in the universe and began exploring it. Though the Q could not comprehend the Precursor's designs, they decided not to interfere, remaining passive observers to the course of the cosmos. Eventually, the Precursors assisted the Q in creating their Q Continuum, a sub-pocket of their Domain. By the time the Progenitors, the first known humanoid life in the universe, first arose in the Milky Way galaxy around 4,500,000,000 BCE, the Precursors had already receded from more mundane affairs. Instead, they were mostly to be found in the Domain. Though their influence began to wane as the newborn sentient species of the universe began spreading throughout the galaxies, the Precursors would still keep an eye on their creations; life in the universe was never entirely abandoned.

#### Recedence

In the Milky Way, the Precursor's increased absence allowed the Thrintun to rise, using their powerful telepathic abilities to create a vast Slaver Empire which encompassed the entire galaxy. To free the countless species who suffered under their oppression, and to prevent their tyranny from spreading to other galaxies, the Tnuctipun led an alliance of other species in a rebellion against the Thrintun. The massive war lasted many centuries, and though the Tnuctipun implored the Precursors to intervene, no help came. Eventually, the Thrintun constructed a powerful psionic amplifier in the center of the galaxy and used it to send a suicidal telepathic command to all life in the Milky Way. This devastating endgame resulted in the complete extinction of 90% of all life in the galaxy; the remaining life was eventually bolstered by the many Thrint food yeasts which unintentionally eventually seeded many barren worlds with life in the coming eons.

The Thrintun's massive machine was set to repeat the suicidal command at regular intervals, and was much to powerful to be destroyed. Even the Q, who possessed nearly limitless control over most forms of matter, were unable to harm the machine, a powerful Precursor-based neural physics construct. To protect the Milky Way from future telepathic signals emanating from the machine, the Q constructed a massive energy barrier which emanated from the galactic center and encircled the entire galaxy, looping around in a donut shape. This barrier would have the unintentional side effect of complicating FTL travel outside the margins of the galaxy using conventional slipspace, hyperspace, and warp methods.

#### Betrayal

Billions of years later, life re-emerged in the Milky Way, leading to the golden age of new species such as the Forerunners. Natives of the planet Ghibalb, the Forerunners spread quickly and came to encompass much of the galaxy in their domain, called the Ecumene. Around this time, the Precursors announced that they would judge one of the sentient species in the universe for the honor of ascension to the Mantle of Responsibility, the Precursor's assumed role of guardianship over all life. After much deliberation, the Forerunners were chosen for this task. However, after a time the Forerunner were judged to be unworthy of taking on the Mantle, and the decision was reversed. Instead, the Precursors decided that the responsibility would fall on the shoulders of another race; a collection of hominid species which would eventually be referred to as humanity, hailing from the planet Erde-Tyrene.

The Precursors announced their decision to the Forerunners around 10,000,000 BCE. The Forerunners were furious at being passed over, especially since the humans were a primitive race, not yet advanced beyond the hunter-gatherer stage on their homeworld. To many Forerunners, the notion that these primates, little more than animals at this point, could eventually prove more worthy to hold the Mantle was inconceivable. Devising a way to enter the Domain, the Forerunners furiously retaliated against their creators using destructive weaponry, driving them to near-extinction. The Precursors, utterly shocked at the violence and destruction which the Forerunners showed themselves to be capable of, did little to fight back or defend themselves. Finally, the last remaining Precursors were pursued to the Milky Way's satellite galaxy, Path Kethona. Bypassing the galactic barrier using probability mirrors, the Forerunners reached the satellite and concluded their campaign of extermination. According to the Precursors, the Forerunners struck against their creators unprovoked, while certain Forerunners who learned the truth later on insisted that the Precursors had planned to wipe out the Forerunners first.

#### Return

A few Precursors escaped the Forerunners, going into suspended animation in the far reaches of space. The hibernation, which entailed the Precursor being broken down into a molecular dust, was meant to eventually regenerate into their past forms. However, over millions of years, the dust was modified beyond its original programming by the Precursors themselves. Now, instead of reconstituting the Precursors, it instead induced madness and grotesque mutation in every lifeform that came in contact with it. This collective form would later be known as the Flood. Far from accepting failure and extinction, the Precursors viewed the Flood as a means to bring unity to the universe, as well as a method to punish the Forerunners for their insolence. Vowing that none of their creations would rise against them again, the Precursors decided that all life would be deprived of free will and merged into one; in the end, the sum of the Precursors' creation would be a reflection of themselves and the suffering their creations caused them. By encompassing all life within itself, the Flood would finally create the ultimate lifeform which it had always sough to make. To it, this was the ultimate fulfillment of the promise of Living Time, the joy of life's interactions with the cosmos.

Around 107,445 BCE, ten million years after the Forerunners' genocide of the Precursors, humanity's fledgling interstellar empire came into contact with the Precursor powder which would, over several centuries, bring forth the Flood plague. The Flood initially ravaged humanity's colonies until receding from the galaxy on its own accord, waiting for a better moment to exact their final vengeance on the Forerunners. During this time, the Flood spread to other galaxies, eventually leaving them completely forsaken. During their first assault on the Milky Way, the Flood had intentionally allowed some humans to go uninfected, leaving the implication of a possible cure that would misdirect efforts in its next assault, while the truth of the humans' genetic attack on the Flood was lost until it was far too late. Around the same time, an Isu exploratory group led by Yprin Yprikushma discovered a small planetoid at the edge of the Milky Way. Hidden within it was a large stasis capsule containing an ancient being whom they later named the Primordial—in fact the last intact Precursor, mutated to survive the passage of eons. They transported the capsule and its captive to the First Civilization capital world of Charum Hakkor and found a way to communicate with the being, which claimed to be the last Precursor.

When human scientists questioned the imprisoned being as to the nature of the Flood, the Primordial's response horrified the humans so deeply that many of them committed suicide. Around ten thousand years later, the IsoDidact interrogated the Primordial on Installation 07, receiving only vague responses as to the fate of the Precursors and their relationship with the Flood. Enraged, the IsoDidact then executed the being. The Primordial faced its end with calm satisfaction, stating that the Forerunners' defiance and, indeed, its own death through the artificial passing of a billion years within an accelerating chronological field, would only add up to the total "sweetness" of life's struggles while asserting its confidence that all life would still succumb to the Flood in the end. The Ur-Didact later discovered that the Gravemind retained the thoughts and memories of the Primordial; before its demise, the being had transferred its consciousness into the Flood's compound mind.

#### Defeat

In the final hours of the Forerunners' war with the Flood the Gravemind sent a group of imprinted humans, including Forthencho, Lord of Admirals, to deliver a message to the Librarian, who was stranded on Erde-Tyrene. Forthencho revealed to her the truth about the Precursors and that the Domain was, in fact, the mythical Organon, which would be destroyed by the Halo Array's immediate firing. By withholding this information until the very end, when the Halos' activation could no longer be stopped, the Precursors ensured that the Forerunners would unwittingly destroy all records of their history and their cultural heritage, or "kill their own soul" as phrased by the Librarian. This was the culmination of the Precursors' insidious plan of vengeance against the Forerunners, set in motion ten thousand years earlier with the revelation of the Flood. While the firing of the Halos seemingly quelled the Flood, the Precursors (through the Gravemind) had already accomplished what they intended: to punish the Forerunners for their defiance not only directly via the Flood, but also allowing the Forerunners' own scheming and internecine feuding to gradually tear down the Forerunners' deepest-held precepts and beliefs. By the time of the Halos' firing, in addition to the near-extinction of the Forerunner species, the Forerunners were forced to admit their many failures and give up the Mantle, ensuring that they would not rise again despite their Pyrrhic victory.

As transsentient beings, they existed on a level beyond that of conventionally sapient biological organisms; they were described as "dreamers and makers whose minds transcended many realms and having infinite forms, many voices, and singular purpose".[8] The Precursors were not tied to any particular physical form, assuming any shape as they saw fit; they would allow themselves to die away and be evolved anew over and over again, taking on numerous incarnations both physical and immaterial. They lived through different stages of technological and cultural development countless times, being at times hyper-advanced and spacefaring and at others living primitively and remaining confined to their worlds.[9] The Precursors based their existence around the philosophical concepts of the Mantle, Living Time, and a meta-technological mechanism known as neural physics, which enabled them to manipulate the fabric of the universe. According to the philosophical aspect of neural physics, the universe itself is a living entity, though vastly different in nature and scale from organic beings.[10] The Precursors' stewardship for all life involved the belief that all experience of biological organisms enriched the greater, universal whole,[11] something they experienced firsthand through the constantly changing nature of their own existence. To contain their vast knowledge and experience the Precursors created the Domain, a transcendent quantum reservoir of information later accessed by the Forerunners.[12] The Precursors were not strictly benevolent, considering strife, pain and indeed evil an inherent part of the universe. The struggles of good and evil, the pleasures and pains of life, added to the 'sweetness', a sensation or emotional state that seemed to not have a human-analogue.

The Precursors were responsible for seeding the Milky Way with life, creating the galaxy's diverse composition of species to become "new tools and companions", and engineered millions of solar systems. Over time, they would also judge whether a species was worthy of the Mantle, their assumed role of guardianship of all life. The humanoid species native to the world of Ghibalb, who would come to be known as the Forerunners, were next chosen for this task. Originally created by the Precursors to serve as their assistants and adjutants,[7] the Forerunner were eventually judged to be unworthy of taking on the Mantle and the Precursors instead decided that the responsibility would fall on the shoulders of another of their creations; a collection of species referred to as humanity, hailing from the planet known as Erde-Tyrene. When the Precursors announced their decision to the Forerunners around 10,000,000 BCE, the latter furiously retaliated against their creators and drove them to near-extinction, first in the Milky Way and eventually in the satellite galaxy of Path Kethona; only a small number managed to escape the Forerunners' campaign of extermination. According to the Precursors themselves the Forerunners struck against their creators unprovoked,[13] while certain Forerunners who learned the truth later on insisted that the Precursors had planned to wipe out the Forerunners first.[3][14]

The Precursors were thought to be the first sentient species to arise in the universe, predating the Progenitors, Q, and other ancient species. In time they became the most advanced and intelligent beings in the cosmos, and with this power they journeyed across space creating and seeding life, both organic and synthetic, and ensuring peace, wisdom, and prosperity for all. They discovered the spiritual concept of Living Time, the metaphysical relationship between the universe and its creatures, and developed the science of neural physics, the art of using Living Time to affect and change the cosmos in various ways. They also developed the Domain, a neural physics archive of all of their collective knowledge. The Q developed their own alternative to the Domain, a sub-dimension known as the Q Continuum, in which they resided in order to evolve beyond their physical bodies.

## Biology

The Flood is an anomaly in the normal biology of lifeforms; their mode of growth and reproduction would make them incompatible with any natural ecosystem. They are extremely adaptive, and transform hosts to suit the species' current needs.

Capable of surviving extreme temperatures, underwater, and even in the vacuum of space, the Flood can withstand the varied environments of virtually all known inhabited planets. However, the Flood seem to thrive the most in moist and humid areas; it is thought that the extremely cold artificial weather patterns near certain important areas of the Halos are intended to hinder the Flood. In order to give themselves ideal living conditions, the Flood will transform the environment to better suit their needs, altering the atmosphere and covering solid surfaces with Flood biomass.

#### Flood Super Cell

All Flood biomass is made of a unique, undifferentiated "Super Cell", which relays information to other cells and coordinates cellular assembly, much like the conventional neural cells of many sentient species. The Flood Super Cell physically resembles human neuron and glial cells, with a central cell body and many tendril-like, branching structures.The Super Cell is capable of moving in coordination with other cells around it, and can be arranged to replace the functions any bodily organ that is required for the Flood's use. Because of this versatile combination of traits, the Super Cell is sometimes referred to as "thinking muscle."

In the absence of a Gravemind, the Flood possesses only basic coordination; they are incapable of forming complex strategies, and focus solely on attacking and infecting nearby sentient organisms. This stage of a Flood outbreak is known as the Feral Stage. At this stage, the Flood seek to accumulate massive amounts of calcium and biomass, eventually leading to the creation of a Flood hive and the beginnings of a proto-Gravemind.

#### Hive states

An organized mass of Flood biomass, known as a hive, can exist in several different states of operation. In the maintenance state, the Flood is focused on the continued repair and function

### Infection

In order to reproduce and grow in biomass, the Flood needs to infect and assimilate other life-forms. While capable of infecting nearly any organism, the Flood shows a strong preference for sentient, sapient life-forms. Assimilating the cerebral tissue of sentient life-forms allows the Flood to directly increase its overall intelligence by absorbing the knowledge, experience, and memories of an infected individual.

The first stage of a Flood outbreak is typically initiated by contact with Flood spores or even more reduced forms of Flood biomatter, should no extant Flood forms be present. Once a basic infestation has been established, Flood infection is typically carried out by infection forms, which are some of the most complex forms that can be generated from Flood biomass during the Feral Stage. Upon sighting a host, a pod infector will leap for the most accessible area of the victim's torso; if the target is an armed human or other bipedal species, this is typically the left side of the chest below the neck, as most combatants will expose this area while shouldering their weapon. Upon contact, the pod infector will rasp away at clothing and flesh until it has burrowed into the chest cavity, mortally wounding them. As the host dies, the pod infector extends tentacles that tap into the victim's spinal cord or other nerve center, forcing a "match" with the nerve signals previously produced by the host's living brain.

To begin the physiological conversion of a host, the pod infector injects encapsulated Flood Super Cells into the body. As it does so, the form analyzes the entire genetic code of its host, allowing the Flood to determine the most effective use of the victim. Simultaneously, the inserted Flood cells capture and break down the host body's cells into organic raw material, which is then absorbed and assimilated into the attacking Flood cells.

The Flood infection then uses the absorbed biomass to create new masses of Flood Super Cells. As the Flood continues to use the resources of the host body, particularly its calcium reserves, the parasite's own cells build upon and augment the framework of the host to produce one of a variety of Feral-Stage Flood forms. This entire process, from the initial kill to total control over a fully mutated host body, takes only a matter of seconds.

The infection process is not limited to living hosts; organisms that are already deceased are also susceptible to infection. As long as the host has not decomposed to the point where the body and nervous system have completely deteriorated, the Pod infector can infect and convert the host.

The Flood infection utilizes the host's biological content as the fuel for its work, which is consumed and employed at prodigious speeds. From the beginning until the end of this complex, multi-step process, the pod infector keeps the body "alive" by chemically isolating the host's dying brain, preventing the signals of brain death from reaching the rest of the body and causing it to shut down, which is an essential part of the parasite's mission of consuming and converting the host organism.

While the pod infectors are an effective and economical means of delivering infection, particularly against armored targets, the Flood can infect hosts through other means. The original infection form used by the Leviathans was that of the Markers, neural physics-powered objects which transform dead biomass into material ready to be made of use by the collective. Later evolutionary stages of the infection yielded other methods of infection. Flood spores, if inhaled, can transform a host into a combat form. This is the Flood's primary means of infection when an outbreak reaches a certain point: Flood spores will be deployed into a local biosphere in copious quantities, instantly overwhelming any unprotected biological targets. Flood conversion may also be initiated through contact with lacerated tissue, making any Flood form a potential vector for infection. Even the most basic form of Flood genetic material is virulent; once inserted into a host, it will mutate the host's DNA over the course of generations until it is capable of forming its own Flood super cells. When infected by these mechanisms, host organisms tend to mutate at a more restrained level that maintains the structure and form of the infected life form, albeit with a significant number of haphazardly placed tendrils, claws, and minor organs, such as sensory stalks.

#### Neurological

Pod infectors selectively target species that possess sentient intelligence and are of sufficient biomass, and can infest intact or lightly wounded dead bodies. As a host organism is killed by the initial attack, Pod infectors use tendrils that pierce the skin of the host and find their way to the spinal cord. They then synchronize with the host's nervous system and gain control of their body, replacing its now-absent consciousness with the ravenous and voracious psyche of the Flood. Any useful information present within the memory centers of the host's brain, such as battle strategies and technical knowledge, is retained for use by the Flood. Despite this lingering of certain memories, no trace of the original mind remains; only a simplistic and primal urge to assimilate other species drives the organism after infection. However, the entirety of the host's mental content is seemingly absorbed and added to the whole, as the Gravemind has shown to be able to generate its victims' consciousnesses within itself.

In isolated cases, such as when the Flood seek very specific information from an individual's mind, they utilize an alternate method of infestation that does not subdue the host's consciousness immediately despite mutating their physical form; this allows the Flood to "burrow" into the host's mind, eventually giving them access to the entire scope of the host's memories.

When the Flood have amassed enough sentient hosts to form a Gravemind, then their behavior becomes far more coordinated, and the Flood collective becomes much more deadly as a result. In addition to its neural physics abilities, the Gravemind may also physically speak directly through combat forms and pure forms under its control.

#### Physiological

While baseline neurological assimilation is largely the same regardless of host species, the Flood infection process includes physiological transformations, which vary depending on the host and the Flood's present need for specialized combatants.

Upon being infected, higher-level species capable of combat are typically transformed into combat forms. The host's physiology is completely "rewritten" during the infection process: organ-based systems are corrupted, organ-specific functions are decentralized, and body cavities are decayed, making hitbox-selective incapacitation impossible and brute force incapacitation difficult. Due to the lack of a central nervous system, decapitation will neither stop or slow a combat form.

Furthermore, munitions with high speed and penetration, such as sniper rifle rounds, are usually ineffective against combat forms. Picking off selective areas of a combat form leads to no wide-scale physiological impediments, and the projectile will punch through the decayed flesh rapidly, exiting through the other side of the combat form without dealing any major damage.

To facilitate melee combat, combat forms generate tentacles and claw-like structures, which protrude from the host's arms. Generally, a single arm develops into a clawed appendage, while the other retains the capacity to manipulate objects, such as firearms. The rapid growth of these structures tends to push aside and break apart the host's hands and forearms.

Combat forms can strike with devastating force, move with tremendous speed and agility, and jump to great heights, displaying physical abilities far beyond those of the host organism while it was alive.

The price for these formidable abilities is that the required metabolism is so rapid and extreme that the host organism's corpse is rapidly broken down by the parasite. This is dramatically demonstrated by the rapid decomposition and disintegration of an infected life-form, which will eventually become a stunted, bloated, mobile generator and incubator for more pod infectors, which is commonly known as a carrier form.

Pod infectors and pure forms sense their surroundings using specialized tentacles, which are tipped with red ganglia. Exactly how these organs work is unknown; they may provide visual or chemical information, or perhaps a combination of both. In combat forms, these tentacles typically protrude from the chest cavity where the pod infector is housed; in pure forms, they are located on the front of the "head" segment.

The described changes occur when the Flood has still yet to overwhelm any meaningful resistance in a given locale. When this has been accomplished, available organisms will no longer be used to create purpose-built combat forms but are instead used to create a Gravemind or simply broken down and processed into biomass for a Flood hive.

#### Metaphysical and technological

Although it would be accurate to call the Flood biological on the most basic level, as an outbreak advances, it becomes a highly powerful self-replicating swarm which will harness any means — philosophical, ideological or technological — to perpetuate itself and its goals. These aspects were most prominently demonstrated during the two major outbreaks in the Forerunner era, particularly the Forerunner-Flood war.

The Flood's most notable meta-biological aspect is the logic plague, an abstract infection carried along information transmission and exchange, typically used to subvert AIs. Mechanisms used to perpetuate this infection range from subtle philosophical persuasion through mutual conversation to more predatory techniques, such as swarming AI networks with a self-replicating information infestation with the ability to convert most machine intelligences near-instantaneously. In the later days of the Forerunner-Flood war, the Flood was able to spread the logic plague through any of its biological forms or infected ancillas.

During its war with the Forerunners, after accumulating sufficient intellectual capacity and processing power in the form of several planetary Key Minds, the Flood re-gained the ability to manipulate neural physics, which served as the foundation of Precursor technology. This enabled it to control the Precursors' formerly dormant structures—most prominently star roads—and use them as weapons against the Forerunners, as well as manipulate space-time to become incompatible with Forerunner slipspace travel. On a more abstract level, the Flood's connection to neural physics caused the Forerunners to experience the very space-time around them as being increasingly hostile. Upon the development of a Gravemind, the Flood becomes capable of what can be described as telepathy among its hosts; given the Flood's origins, this ability may be related to neural physics.

The Flood is able to use any technology it has assimilated, often to a superior degree than the original creators of said technology due to its vast base of knowledge and intellect.

### Developmental stages

A Flood infestation goes through four distinct developmental stages:

1. During the **Feral** stage, the Flood are at their simplest form: they communicate via pheromones and have the instinct to harvest enough calcium to establish a viable Gravemind.
2. The Flood become truly dangerous during the **Coordinated** stage: at this point, they are controlled by the Gravemind that was created in the first stage.
3. In the **Interstellar** stage, the Flood take control of space-faring technology which they use to consume the local star system. This is also the stage in which Key Minds first appear. Subsequently, they spread throughout the local galaxy to infect more species.
4. The **Transgalactic** stage is the penultimate stage in which the Flood utilizes all acquired means and technology to depart to uninfected galaxies to further replicate. This has occurred a handful of times, and is the current stage of the infection on the universal scale.
5. The **Universal** stage is the Flood's endgame, its theoretical final stage and the ultimate goal of the infection itself. In this hypothetical future stage, the Flood will have accomplished its goal of assimilating all life in the universe. Where it would proceed from here is unknown.

### Countermeasures

#### Small-scale

It is impossible to stop a Flood infection once Flood Super Cells have entered a host. There is no cure to Flood infection, although there have been many attempts. While the Forerunners could not find a cure for Flood infection, the Composer was designed to eliminate its effects by extracting a Flood victim's consciousness into digital form and then re-inserting it in an artificially-constructed body devoid of infection. However, the Forerunners never perfected this process and any imprinted bodies died soon after, due to the Flood somehow resuming the infection in the new body. The Forerunners attempted to use various means to slow down this process, including a specially designed harness of mesh and wires, which would apparently counteract the infection. The victim would retain most or all of their mental faculties and self-control, although their body would continue to be mutated by the Flood. This countermeasure was only temporary, however, and the victim would eventually either decay and die or be fully subsumed by the Flood.

Although initially used to treat those with small-scale Flood infection already present, the Composer was eventually used by the Ur-Didact to convert his Prometheans, as well as a large number of humans, into AI constructs for his war machines, in an effort to combat the Flood more effectively and without risk of infection.

#### Large-scale

Since the Flood are a parasitic life form, they depend on other organisms for survival. Thus, the most effective way to stop a large-scale infestation is to take away their energy sources. The Forerunners first attempted this by bombing large population centers and destroying inhabited star systems via supernovae, but this was seen as one of their last resorts and as such was performed too late in the war to make much difference. The last resort was the use of the Halo Array, which used neural physics to kill all sentient life in the galaxy and starved the Flood into remission. However, the Forerunners' plan included some measures to preserve the various species of sentient life and return them to their home planets, allowing the Flood's energy source in the Milky Way to persist. Unfortunately, at the same time, specimens of Flood spore cells were kept for analysis on the Halo installations, allowing the threat of the Flood in the Milky Way to be merely forestalled and not eradicated.

Environmental stimuli seem to have an effect on Flood metabolism. In the event of a Flood outbreak, Halo installations create a quarantine zone around the affected area, inside which the ambient temperature is drastically lowered. At least one Flood research facility used low temperatures to keep its specimens inactive and dormant as it studied them. At least one of the Halo installations' Control Rooms was located in a snowy environment, possibly to hinder escaped Flood in their attempts to reach it.

The Flood are also vulnerable to temperatures on the other end of the spectrum. Plasma weapons will burn through Flood tissue; the Forerunners incorporated directed-energy weapons into their Sentinels, indicating that they had determined high-enthalpy energy weapons to be the best 'basic countermeasure' available to fight the Flood. Known examples of Forerunner personal weaponry appear to be geared toward the disintegration of organic matter, also reflecting the Flood's vulnerability to extremely high temperatures.

#### The "cure"

During the Thousand Year War, humanity believed they had discovered a way to defeat the Flood. Using genetic engineering, a third of the human population was altered to carry a set of specially designed genes. This group of humans was then allowed to be infected by the Flood. Once the genes were exposed to Flood DNA, they triggered a cascade of cell destruction that spread throughout all Flood biomatter. The majority of the Flood died off as a result, although they would return in full force ten thousand years later. All information regarding this "cure" was destroyed by the humans as a final act of revenge against the Forerunners, leaving them unprepared for the second Flood strike.

In reality, while humanity's efforts indeed produced the intended result and repulsed the Flood threat, it was later revealed by the Primordial that the Flood retreated by its own initiative, as humanity was not yet to be "punished" by the Flood. As such, humanity's survival was in fact due to the Flood's deliberate decision not to infect human populations, as the Precursors had determined to use the Flood to punish the Forerunners first.

After the Flood began to ravage the Forerunners' Ecumene, Forerunner scientists led by Master Builder Faber tried in vain to extract information on the cure from humans' ancestral memories, imprinted as part of their *geas* by the Librarian, unaware that the cure never really existed.