I think I read somewhere (maybe halopedia), that the Gravemind had been lying dormant beneath the surface of Delta for thousands of years. If I remember correctly then the first time the MC encounters the Flood on Delta is after Regret is taken out. MC is captured by the Gravemind and taken to a cavernous lair. Let me see if I can find it somewhere. EDIT: Yeah here it is. [quote]Through neglect shown by the Monitor of Installation 05, 2401 Penitent Tangent, a Flood outbreak occurred, and the Gravemind was able to find enough biomass to rebuild itself deep under the Library of the installation. It assimilated the dead Prophet of Regret into itself and also captured the Monitor.[/quote] [Edited on 10.03.2012 4:03 AM PDT]