In the *species of the universe* (I forgot the original name), it says the Flood are an extra-galactic life form. Make whatever theory you would want from that, but I think the most important overlooked information is.... The Forerunners before us adopted technology from an even older race of beings called the Precursors. Proof is in the Halo 3 Beastarium, and in the conversation between Didact and Librarian they say: L: I'm close to finishing the task. The indexing and the archival processes are as complete as I can hope for. If we wait longer, we risk catastrophe. The thing has already destroyed every colony on my side of the line. Please. Activate the Array. D: No. Activation is murder. A genocide larger than [this galaxy] has ever known. We are sworn to protect life not destroy it! [u][b]That is the Mantle we were given to carry.[/u][/b] L: [u][b]The Mantle. You still hold to that [belief] after all that has happened? After this thing has consumed a million worlds?[/u][/b] Can't you see? [u][b]Belief in the Mantle sealed our doom![/u][/b] Weakened our [protectorates], bred dependence and sloth. Our [so-called Guardianship] has stripped those we would keep safe of any capacity for self-defense! Were we such noble [Guardians] when we drew our line and abandoned billions to the parasite? D: [u][b]The Mantle has not failed![/u][/b] I've already razed scores of worlds--sterilized systems, routed and [disintegrated] the parasite! We're learning its tricks and strategies. We can halt this thing! And we can follow in Their footsteps! There are no unstoppable forces in this universe. There are no immovable objects. Everything gives if you push hard enough. L: And what about us, Didact? We've been irresistible and immovable for too long. Maybe it's our turn to give. //FRAGMENT ENDS What is this mantle, and who's footsteps are they following in? Here is some information I found the the Precursors The Precursors were mentioned in the Bestiarum as the race preceding and mythologized by the Forerunners, being theoretical "Trans-sentient" beings [1], having the ability to travel between galaxies and accelerate the evolution of intelligent life. The Precursors achieved a higher level of tier one technological advancement than the Forerunners, so tier zero technology is attained, (Trans-sentience) on the Forerunners' Technological Achievement Scale. [edit] History Not much is known about them, but information that can be found by text from the logs stored in the terminals around the Ark indicates it is possible that the Forerunner 'Mantle' (Guardians of the Galaxy and all life) was handed down from "legends of the past"; the Precursors. It has been presumed that the Precursors viewed the Forerunners as their own legacy, continuing their work after they departed, much in the same way Forerunner viewed humanity before the activation of the rings. In this way, humanity is related to the Precursors. Any further knowledge concerning the Precursors or their eventual fate is unknown. Because the stone structures found on Delta Halo do not seem like they were built by the Forerunners, (The Forerunners, as far as we can tell, only built with metal.) it may be possible that the structures were built by the Precursors. Also, Cortana noted that the stone structures were "sacred" and "protected". This is cause to believe that they were built by the Precursors and moved to Delta Halo. [edit] Trivia * The term Precursor means "one that precedes and indicates the approach of another". The term supports that it surpassed the Forerunners. * The Precursors were the only civilization to achieve Tier 0 of the Forerunner Technological Advancement Scale and to exceed the Forerunners in technological advancement. * Precursor in Latin can mean Forerunner, but this is only due to the language's ambiguity. * In Halo: The Fall of Reach, Dr. Halsey uses the term Precursor to describe the alien race that created the crystal found on Sigma Octanus IV. So my belief is that the Precursors inhabit the planet at the end of Halo 3's Legendary ending! And just for fun.... A moon in the G617 system, G617 g1 was the first world in the Milky Way to be infected by Flood. A Forerunner-based research team called the Primary Pioneer Group made active landfall on the bordering town planet known as G617g and they initially reported some interesting findings. Despite previous assumptions and conjectures, the world could support sentient life despite the lack of fauna, which they intended to review more closely. The protocol allows them to dispatch a secondary batch of researchers called the Advance Survey Team-Alpha. After a week of no communication, the Forerunners who were remotely monitoring this new discovery become worried.[1] In their response to the initial testimony and report, those monitoring it advised that they would send a military detachment to the site shortly to uncover why their two exploratory teams have halted communication. That would be the last time the Forerunners had any contact with G617g, and it was the beginning of the largest war their galaxy would ever see lasting about three centuries. No one knows why the Flood were dormant on G617g or even how long they had been there before, but it is believed that due to their vastly different physiology, they traveled to our galaxy from another.[2] Theory time! [Edited on 07.13.2008 12:28 PM PDT]