MAJOR SPOILERS BELOW
At the end of Halo 5, we saw cortana return with quite ambiguous motives. She wanted to rid the universe of evil while protecting Blue Team in a cryptum during the 10 000-year process it would take. What “ridding the universe of evil” means is quite unclear, but what we do know is there will be a Halo ring involved in the process. The legendary ending of Halo 5 shows Cortana on a Halo ring, and what better way to kill evil than to activate a Halo ring?. I have two theories on where Halo 6’s story will go:
First Theory
Remember when Cortana was abducted by The Gravemind in Halo 2, her genetic code may have been manipulated by him, after all that’s what The Gravemind does; he manipulates. The Gravemind may have known that the only thing between him and the floods salvation was John 117. So, he manipulated Cortana so that when John rescued her, the Gravemind would have control over Cortana. As mentioned before, the legendary ending of Halo 5 shows cortana on a Halo ring. The gravemind could make it seem as if cortana was going to activate the ring, and the only way for that to not happen would be for John (or who ever is helping him) to destroy the rings.
Second Theory
Cortana plans on activating a Halo ring, but she needs a human to activate it. This may be why she was initially going to protect Blue Team in a cryptum so she could exploit John’s emotional attachment to her to activate the ring. But since Blue Team escapes the Cryptum thanks to Exuberant Witness, John won’t activate the rings. Instead he will try to destroy them. John may even summon the flood to aid him in stopping Cortana from activating the rings like in Halo 3.
What do you think?