No civilization that grows beneath a veil of stars can resist assigning some sort of
meaning to them.
When humanity first escaped the confines of Earth and began exploring the universe, they
brought with them, like so many others before, an earnest hope that some grand understanding
or purpose might be found in the darkness.
But the galaxy raised only more questions.
The greatest of which came from the ruins of a species that would become known as the
Forerunners.
How a race of such sophistication and power could disappear in an instant, and the purpose
of the mysterious relics they left behind, would lead to war and carnage by those who
followed them.
But the answer would be far worse than this question, for it came in the form of the Flood.
Parasitic, invasive and extraordinarily adaptable, the multitude of life forms and mutations
that constitute the Flood have no equal in the natural world.
They are an aberration within the study of biology and are incompatible with every natural
ecosystem.
Yet despite their grotesque appearance and typically wild behavior, as an outbreak spreads
the Flood have the potential to become a self-aware and highly intelligent entity, matching or
surpassing any civilization in galactic history.
They are an almost perfect life form, but one that can only persist through the extermination
of all others.
In their most basic form, the Flood exists as a miniscule airborne particulate, known
as flood spores.
Their only purpose is the infection of other forms of life through a unique Flood “super-cell”.
These super cells coordinate cellular assembly, but are also capable of acting in conjunction
with one another, creating or mimicking any bodily organ as required, resulting in a kind
of “thinking muscle”.
When these spores are inhaled, come into contact with an open wound, or through some other
method enter into a living or recently deceased organism, super cells are released and act
as catalysts for a rapid transformation.
The Flood Spore hijacks the body and nervous system of an infected host, breaking down
their cells into a raw organic material which can then be assimilated.
As this process accelerates, more super cells are created and an organism's compounds are
repurposed.
Calcium in particular is used to create the framework of a new Flood life form to which
biomatter is then grafted.
The host's brain is kept chemically isolated throughout the process, ensuring no signals
can interrupt it.
Depending on the complexity of the life form, this intricate, multi-stage transformation
can take only seconds.
The earliest Flood lifeforms created by their Spores are generally grouped into a category
of “infection forms”.
While exponentially more complex, these parasites have a similar purpose; seeking out new life
in which to spread Flood supercells.
Unlike the largely passive spores, these parasites actively seek out new hosts.
They can take different forms, each uniquely suited to a different environment, but the
most prevalent are “pod infectors”.
These are far more effective than spores alone, and the primary vector of a flood infection.
Small in size and resembling balloon-like creatures, pod infectors overwhelm larger
and stronger organisms through sheer numbers.
With numerous grasping tentacles, they can chip away at armor, clothing and flesh before
probing into the victim’s nervous system, typically through the chest.
Once Flood super-cells are released, the transformation repeats itself.
Even brief contact with a pod infector can be fatal, once a supercell has been released,
there is no reliable means of slowing its progression.
Only in exceedingly rare cases, when an infector pod has been wounded or significantly aged,
has a host body survived the process, but is still only able to exert control over their
own body during brief, random moments,
Organisms successfully afflicted by pod infectors might be turned into pod infectors themselves,
but often the infection will instead begin creating new forms of flood life.
Formerly sentient organisms might be turned into any number of “combat forms” and
tasked with further spreading and defending the Flood infection.
Rather than completely overwhelming the host, the parasitic growth lodges itself somewhere
on the body and begins growing new limbs and appendages which extrude outwards, seemingly
randomly.
Certain organs are preserved, or recreated, allowing the body to remain functional.
The overall physical appearance and behavior of these combat forms varies drastically,
depending on the species originally infected.
Eventually, flood supercells will completely overwhelm a combat form and its usefulness
in this role will be severely impaired.
When this occurs, the parasite will begin spontaneously generating new pod infectors
within the host body.
This causes the organism to swell to grotesque proportions, with any appendages and limbs
reduced to flailing stumps.
These “Carrier forms” act as mobile incubators, producing pod infectors indefinitely.
When potential new hosts are present in its immediate vicinity however, it will attempt
to move towards them, before detonating itself in a biological explosion similar to that
of a fragmentation grenade.
Clouds of flood spores are released and the infection is allowed to spread further.
As with infection forms, carrier forms can be very different in appearance and capability,
depending on the local environment and native species present.
During the earliest phase of a Flood outbreak, when only small groups of individuals have
been assimilated; infection, combat and carrier forms will act in an animalistic and senseless
manner.
During this feral stage, their overriding instinct will be to spread the infection,
but without any strategy or higher-order thinking.
Despite their rudimentary behavior, by some kind of instinct, even the most basic form
of the Flood will prioritize more intelligent species for assimilation.
In one of the least understood aspects of their propagation, parasitic life forms can
retain the intelligence and memories of their host.
These are then shared across every flood organism, collectively forming a nascent hive intelligence,
a critical component of the infection’s development.
This single consciousness grows more sophisticated as the outbreak spreads.
Combat forms will begin to reliably use weapons and tools with which they were familiar in
life, and even begin to operate complex machinery.
Infection forms become able to coordinate their activities to rapidly acquire biomass
from sentient lifeforms.
At every level, flood life forms will exhibit a greater ability to solve problems and react
to outside interference.
At an indeterminate moment, this consciousness will reach a tipping point and the Flood will
begin to enter into a new “coordinated stage”.
From enormous amounts of raw biomass a physical embodiment of the supreme Flood intelligence
is crafted: a Gravemind.
The Gravemind is the highest stage of the Flood’s biological development, directing
the outbreak as a whole to perform intricate tasks and enact complex strategic thinking.
Through the absorption of countless memories it will possess an extraordinary awareness
of entire species and attempt to manipulate or deceive them in subtle or overt ways.
To coordinate its growing capabilities, a Gravemind will begin producing “key minds”,
specialized forms that amplify the effectiveness of the shared consciousness.
The most common key mind is known colloquially as “Abominations” and drastically improves
the abilities of nearby flood organisms.
The Gravemind will additionally attempt to replicate itself, creating additional “proto-graveminds”.
These have the potential to grow into fully formed Graveminds themselves, but no matter
how many there are, they are merely representations of a single shared intelligence.
The capability and capacity of that intelligence will depend heavily on how many key minds
it controls.
Once a Gravemind has asserted itself over the Flood and the Coordinated Stage of the
outbreak is well underway, a new evolution will occur.
The most advanced category of Flood creations, beneath only the key minds, are designated
“Pure Forms”.
Unlike every other Flood organism, these are not created through the infection of alien
hosts, but rather crafted from raw biomass.
Without the restrictions of a host’s body, these can take any number of subforms, usually
adapting to directly counter threats to the greater outbreak.
In the Feral Stage, and even during the subsequent Coordinated Stage, a Flood outbreak might
be misidentified as a natural phenomenon, or a mindless rampaging infection.
A Gravemind might even actively work to encourage this perception.
But the full extent of the Flood’s character becomes truly evident when it acquires the
ability to conduct interstellar travel.
This capability is based on the kind of civilization the Flood has infected, and is not a component
of its innate biological development.
Nevertheless, by commandeering spacecraft, the Flood can enter an interstellar stage,
infecting entire worlds and star systems.
One of its most notable abilities at this stage is the “logic plague” , an abstract
Flood infection carried not through biological means, but rather by transmitted data and
artificial intelligences.
Through this still largely mysterious process, the Flood can begin to directly operate technology,
often to a superior degree when compared to its original operators thanks to the Gravemind’s
immense base of knowledge.
The earliest information on the Flood comes from the Forerunners, which hint that they
are all that remains of an even more ancient civilization.
What is undeniable is that the Forerunners fought an apocalyptic war against the Flood,
in which the power of the hive mind grew exponentially.
Entire worlds were transformed into key minds and the resulting logic plague infected every
forerunner system and network.
With every other method of containing the Flood ineffective, the Forerunners resorted
to a brilliant, yet completely pyrrhic solution.
Rather than attempt to destroy the Flood themselves, the Forerunners rid the galaxy of their food
source, stripping them of any future hosts and their ability to spread.
Through the activation of Seven ring-shaped megastructures referred to as the Halo Array,
the galaxy was purged of all sentient life.
The Forerunners themselves were erased from existence, their last survivors fleeing the
galaxy to seek refuge elsewhere.
Pre-sapient life, carefully conserved on a massive ark, was introduced to their native
environments, now free from the threat of infection.
The war fought between United Nations Space Command and the theocratic alliance known
as the Covenant unleashed the threat of the Flood millenia after their supposed extinction.
Specimens had been preserved through certain Forerunner installations and the resulting
infection grew to substantial size, even forming a Gravemind before it was eventually destroyed.
But while the gestalt consciousness is gone, sporadic Flood life forms remain, locked away
in the forgotten corners of the fallen Forerunner civilization.
A single spore can devastate an entire civilization and with the Covenant shattered and the UNSC
in chaos, there has never been a better opportunity for an outbreak to go unnoticed.
A timeless chorus may yet arise again, one that joins every voice of the galaxy together,
to sing victory everlasting.
A universe of corpses, sharing one grave.