- last post: 01.01.0001 12:00 AM PDT
I assume that it is the Gravemind, because the deep voice sounds exactly like his. Besides, Cortana was left behind with it. The Gravemind could easily relay a message to the chief through Cortana. Besides, Cortana isn't likely to say such things... The Gravemind, however, deserves to say those things. He's definitely defied Gods and Demons. He's still alive, along with his flood brethren, after god only knows how many years. He doesn't want the Covenant to activate anything Forrunner (because it means the end of the flood pretty much) so he'll try and help MC stop the Covenant some way (not directly)
But yeah, those are my opinions.