David Winn (dwinn@airmail.net) writes:
I was reading your section about the Forerunners, and I'm surprised no one has said what I think it obvious: the Flood probably weren't harmful to the Forerunners, or at least not enough to warrant immediate destruction. Maybe they were robotic, or, as one person suggested, hyper-evolved plants, or of some other form of life, but the forerunners probably didn't destroy them because they didn't pose a direct, serious threat to them.
Indeed. It's been proposed that the Forerunner were built much like humans, but there are any number of possible ways that they would not be "appetizing" to the Flood. Lucky us, we and the Covenant seem to be quite tasty, though.