The Coordinated Stage is the second stage of a Flood infestation, over the course of which a local ecosystem is typically fully absorbed. During this stage, Flood population rapidly increases. The Flood Super Cell generates a hive and propagates spores into the local atmosphere in massive numbers. Once sufficient biomass has been gathered, the Flood gains the ability to spontaneously generate Flood Super Cells, removing its dependency on hosts and giving rise to pure forms. On the verge of initiating the Coordinated Stage, the proto-Gravemind continues to be built until it reaches the status of a complete Compound Mind — a Gravemind. It is at this point that the Flood becomes significantly more organized (communicating via thoughts and attacking strategically) and subsequently more lethal than in the preceding Feral Stage. Upon the formation of a full Gravemind, all locally available sentient beings have typically been absorbed by the Flood.
Once it has gained sufficient technology, the Flood will proceed into the Interstellar Stage.
This stage has occurred several times;
- The first was during the Flood's initial rise in the ancient humans' dominion during the events preceding the human-Forerunner wars. After infesting the human pets known as Pheru, the Flood began to infect humans and San'Shyuum, eventually initiating the Coordinated Stage on many human worlds.
- The Gravemind's conception from the planet of G617g gave rise to the Gravemind who made war with the Forerunners and was believed to be destroyed during the first firing of the Halo Array.
- During the Human-Covenant War, Infinite Succor, an agricultural support ship which was part of the Fleet of Particular Justice, was targeted by the Flood. The on-board Legate eventually became part of the biomass reserves being built on the ship by Combat Forms – it is believed to have been in the process of transforming into a proto-Gravemind before Rtas 'Vadumee sent the vessel into the nearest star.
- Not far away on the Truth and Reconciliation orbiting above Installation 04, Captain Jacob Keyes had become an anchor for what appeared to be a proto-Gravemind. This entity, however, had been taken care of as the Master Chief obtained the Captain's neural implants and the proto-Gravemind was later destroyed by Covenant Spec Ops units.
- At some point, a catastrophic containment failure on Installation 05 released the Flood into the Quarantine Zone around the Library, which eventually facilitated the creation of a proto-Gravemind. This became the last known Gravemind. This infestation expanded into the interstellar stage before the Gravemind and all escaped Flood forms were destroyed, reverting any Flood left in the galaxy back into the feral stage.
- During the Second Ark Conflict a proto-Gravemind had formed within the destroyed High Charity from the remains of the Gravemind from Installation 05. Before the proto-Gravemind reached critical mass to become a Gravemind though it was killed by Banished forces led by Pavium and Voridus.
- The Flood in Halo: Combat Evolved were always found without whatever attire their hosts usually wore. In Halo 2, however, this changed, as the Flood then kept the apparel of their hosts for protection, likely a trait of the Coordinated Stage.
List of appearances
- Halo: Combat Evolved (First appearance)
- Halo: The Flood
- Halo 2
- Halo Graphic Novel
- Halo Wars
- Halo: Combat Evolved Anniversary
- Halo 2: Anniversary
- Halo Wars 2