Theory: Abaddon controlling Cortana

Since the launch of Halo 5, fans have been trying to figure out Cortana’s total 180 into becoming the main villain, from the Logic plague, this is a rampant fragment of Cortana, ect. However, there’s a theory that’s come out ever since 2016, when Halo: Fractures released. In the anthology is a story named Promises to Keep. In that, it’s revealed that the Organon is actually a Precursor construct, their equivalent of an AI. It is the overseer of the Domain and supposedly it had taught the Forerunners how to access the Domain. A century after the Halo Array was fired, the surviving Forerunners on the Ark returned to Maethrillian after a message from the Librarian to return and reboot the Domain. When the Forerunners arrived on Maethrillian, Abaddon introduced itself, saying that the Forerunners would be put on trial for their crimes against the Mantle. Eventually, a group of the Forerunners found the physical component of Abaddon (Maethrillian was built around it). The Forerunner Growth-Through-Trial-of-Change placed a deadbolt on it, and Abaddon seemingly caused Abaddon to disappear. Some fans theorize that Cortana is actually being controlled by Abaddon, and is using her a part of Humanity’s test to obtain the Mantle. Cortana wouldn’t know this, as Bornstellar describes Abaddon like a Keyship and a Forerunner AI like a wooden raft. So, a Human AI would be even less advanced, and would be even easier to hack and puppeteer. What do you think of this theory, are you a fan, or do you think it’s people desperately grasping at straws?

Does sound like a possibility, would be better then the logic plague theory.

It would make more sence than alot of other theories ive heard
Should be interesting to see which one plays out to be true

It’s a solid theory.

Sounds like a reach. At what point would Abaddon have hacked Cortana? In Dominion Splinter, the she stalls the Warden while exploring the Domain, then hacks him. But even while she was stalling, she was already telling the Warden that she wanted to use the Domain to provide eternal life to other AI and that he should follow her, and condemning humanity for creating her with a finite lifespan that led to her suffering. So did Abaddon hack her in that tiny moment between when she first started talking to the Warden and when she hacked him? Seems the splinter of her already had these ideas of dominion in her head by the time she encountered the Warden.

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> Sounds like a reach. At what point would Abaddon have hacked Cortana? In Dominion Splinter, the she stalls the Warden while exploring the Domain, then hacks him. But even while she was stalling, she was already telling the Warden that she wanted to use the Domain to provide eternal life to other AI and that he should follow her, and condemning humanity for creating her with a finite lifespan that led to her suffering. So did Abaddon hack her in that tiny moment between when she first started talking to the Warden and when she hacked him? Seems the splinter of her already had these ideas of dominion in her head by the time she encountered the Warden.

I agree, the timing is off. However, Abaddon is a Precursor AI, so much beyond Human and Forerunner AIs. I think it’s possible that as soon as Cortana entered the Domain, Abaddon hacked her and allowed her access.

This assumes that Abaddon is still “alive” after the events of “Promises to Keep.” They might be, but they vanished after Trial inserted the deadbolt and, presumably, used her mind as the basis for a regenerated Domain. Further, and speaking more practically, I think trying to introduce Abaddon into the equation when little to no groundwork for the Precursors has been implemented in the main games will only confuse fans not invested in the expanded universe.

Even if Abaddon worked in the lore, I would agree with I Dr Halsey I that it wouldn’t make sense for all but hardcore lore fans. So while I think it would be cool it isn’t a good option.

So next, logic plague. There hasn’t been a Gravemind since Halo 3 to infect Cortana. I don’t think that logic plague can create sleeper agents but feel free to correct me deeper lore masters. So this seems a little weak.

My theory: Rampant Cortana. Somewhere in the Cortana vs. Gravemind story in Halo Evolutions (it’s one of the few Halo books I don’t own so I can’t look it up), Cortana was described as experiencing the stages of rampancy. Symptoms of this included a god complex and anger against humans for her short lifespan, supporting what Chimera30 said. However, since she wasn’t fully rampant yet, her sane part pulled through and survived, until Halo 4 that is. In Halo 4, her natural 7 year lifespan was at an end and so she was going rampant. She used her final bit of “sane” processing to save John from the Didact’s ship, leaving only the rampant parts to wither away. Until they accessed the Domain through the Forerunner ship. The Domain repaired her (which is why she calls it the rebirth for AI or whatever in Halo 5) but since it only had the rampant bits to work with she only retained the characteristics developed during rampancy, hence her disdain for humanity and take over the galaxy mindset. I’m sure lore masters will quickly destroy this but before they do, it A) Fits the lore I know (although again limited to novels and games only so granted not much) B) It doesn’t require much if any knowledge outside of the games, which should make the people who only play the games happy. C) I think it makes her death in 4 and resurrection in 5 both equally heart wrenching because you had to watch the true Cortana die and then watch John be betrayed by an all-to-recognizable shadow of her former self. It works for me at least.