- last post: 01.01.0001 12:00 AM PDT
Keep in mind, the natural form of the Flood is the Infection form, which reproduces by gaining control of a host and turning the body into a pus filled sack with more Infection Forms in it.
I think 1: The Forerunner found this weird race and kept some of it on Halo for study and the rest of the Flood died out.
2: The Forerunner were experimenting with genetics and screwed up big time. Place emphasis on the screwed up.