When Bungie originally made CE, there weren't any plans for a Halo 2. Halo was planned to be a one-time thing, Bungie was going to move onto a fantasy game afterwards (which is what Destiny is largely based off). [quote]Also: How are the gravemind's tentacles present on the Ark when he was on Delta Halo at the time?[/quote] Gravemind commandeered In Amber Clad and crashed itinto High Charity at the end of Halo 2, hence why High Charity is overtaken by the Flood by the time Halo 3 comes around...