- last post: 01.01.0001 12:00 AM PDT
This is a pretty insubstantial theory, or actually, several theories.
One is that the flood was conquering everything, and the covenant and the forerunners, teamed up and drove the flood into the ringworlds, where they forced the flood into the facilities using their AI's and robots so the flood wouldn't have anything to eat or infect (343 Guilty Spark!) and left the AI to defend the rings in case of the flood breaking loose, but in order keep in safeguarded, made it so that the AI contructs could not use it without the help of one of the forerunners. This of course, brings up my theory that human are the forerunners. After the flood was subdued, the forerunners allies turned on them and eliminated them, but the Halo's were not revealed to the covenant. Maybe the covenant fought them all the way back to a Halo, and they had to make the decision to either try to fight them off, or activate the ring and prevent the Covenant from entering the ring, maybe 343 himself was there, goading them into doing it "Last time, you asked me what i would do if it was my choice, my answer remains the same, the ring must be activated" That is not the exact wording, and I think it did say something about the flood, so maybe the flood had been released as well. Despite 343's goading, the forerunners decided to simply drive them off, or maybe..... use the flood against them. The covenant were nearly destroyed but managed to defeat the flood using the technique of glassing over infected planets. Maybe then the covenant exterminated the human race, or so they thought. Maybe one ship managed to crashland on earth. When the Covenant saw humans again, they recognized their ancient enemy from their histories, and the Prophets naturally wanted exterminate their ancestors ancient enemy. Something that sort of supports this is the fact that 343 kept on referring to the master chief as "reclaimer" maybe 343 was referring to reclaiming their forerunners technology! 343 seemed genuinly shocked that the master chief didn't know that he was about to exterminate all life within a ten thousand lightyears or something. 343 simply assumed the master chief was one of the forerunners coming back to activate the facility.
My other theory still relies on that humans are the forerunners, but maybe they created both the Halo's, AND the flood as a weapon to use against some kind of enemy, Covenant or something. They had created the Halo's as a failsafe in case the flood got out of hand, since they had super technology, they could simply leave the range of it and destroy all life in the sector the flood were in. Naturally a tactic like this would piss the covenant off to no end. There is also the fact that Keyes said he was looking for a weapon cache. It is possible that it was a weapon cache, just not the type he was looking for, it was the ultimate BIOLOGICAL weapon. 343 also said that Halo was built to study and contain the flood and that their survival as a race was dependent upon it. Maybe they had a very powerful enemy that the only thing they had to effectively combat was the flood, so they used to flood to protect themselves. As before, i think 343 was created by the forerunners to manage the flood, but not activate the ring. "A unit with my classification cannot perform a task so important as the reuniting of the index with the core" Even after the chief turned on him, he still said, he would have to find another. That leads me to the conclusion that his programming would not allow him to do it, a forerunner would be the only one allowed to reunite them and activate "Halos final weapon" That of course being a safeguard against their AI turning on them, or activating it at the wrong time.
Thats the most I have typed since school ended. A lot of good ideas tied together with groundless speculation, but i am willing to bet that one of these theories will be at least PART right.