Graveminds think alike
Gravemind was another major antagonist in the Halo series, first appearing in Halo 2 before being destroyed in Halo 3. As a leader of the Flood, Gravemind’s intelligence came from the collective intelligence of every creature the Flood had assimilated. Yet, Gravemind itself was never a singular entity; in fact, Gravemind can be constructed and reconstructed by surviving Flood, and every new Gravemind retains the intelligence and memory of previous Graveminds, making it a virtually omniscient creature.
Though the Flood sat out all of Halo 4, it is hard to imagine them never returning. Much of the series backstory revolves around both humanity and the Forerunners trying to control the Flood menace – they are nearly impossible to kill off completely. In issue #6 of the Halo: Escalation comic series, a lone infectious Flood is revealed on the UNSC ship, Spirit of Fire, which is on a crash course toward an unknown planet. In other words, we may soon see another outbreak of the Flood.