I have threetheories that I think makes some sense of how Cortana could be in Halo 5. AND… two of them do not involve Cortana being alive.

Frank O’Conner has expressly stated that she is gone. We saw that in the game.

So how is it she’s in Halo 5 Guardians? Glad you asked. Let’s look at my theories on this, shall we?

Some spoilers for the Halo 5 Campaign are below. You’ve been warned!

The Ghost Theory

Recall the Librarian in Halo 4? She was in fact dead. The Librarian we saw was her memories digitized and saved. Instead what we saw was her ‘ghost’. This is important to note as Frank O’Conner has said he thinks of Cortana in Halo 5 as being her ghost.

Was the Librarian we saw an A.I.? Well the answer is mostly yes but some definite no. It was a program that made use of the real Librarian’s memories. So the program itself was A.I.-like, but the context of the information was all Librarian.

How does that tie in with Cortana? Well, recall that she ‘broke off’ parts of herself to take on the Didact. It could be that she did something similar to what the Librarian did and downloaded her memories into a server somewhere where they would eventually coalesce  into a form of some kind. John’s (Master Chief) hearing her would fit. If he sees here, then it’s as if he didn’t lose Cortana at all. That’s something 343 doesn’t want to do I think. It would diminish Cortana’s death in Halo 4.

The Geas Theory

This theory is a bit more complicated. First, let’s remember that Cortana ‘spoke’ with the Librarian on Requiem. We weren’t privy to the conversation itself, but the Librarian does tell us this later in the game.

Next, Master Chief gets an ‘upgrade’ or rather is evolved by the Librarian.

So how do the two connect? It’s possible that when Cortana had her interaction with the Librarian, the Librarian was able to download her. When it came time for Master Chief to be evolved, the Librarian uploaded the memories of Cortana to him. Yes, she is digital, so how can she be transferred to a biological being? Well, we certainly do not know the extent of Forerunner technology. As well, we don’t know the extent of Master Chief’s upgrade, other than his now being invulnerable to the Composer’s effects.

So why is it she hasn’t talked to him before the campaign then? Because the Librarian put her in there as a kind of geas. Geas are Forerunner designed genetic commands that are passed on from generation to generation. In this case though, Cortana was to become a very specific geas for Master Chief. Forerunners in their far advanced technology were easily able to implant memories into humans. We’ve seen this before with the ancient ‘Forthenco, Lord of Admirals’. Forthenco’s personality was kept within 343 Guilty Spark during the 100, 000 years between the ancient Human-Forerunner war and the current story line of Halo. Only when there was dire needs (Such as the Guardians become active) would the Cortana geas kick in. It’s not Cortana at all, but her personality that has been imprinted onto Chief. When Chief hears her, it’s all in his mind. Should he see her, it would again be a trick of the geas in his mind. Using Cortana’s personality like this would give Chief at least a part of what he lost. Also, he’d be more apt to listening to her than others with regards to a dire crisis.

Lastly…

Cortana is in the Domain

Again, during her interaction with the Librarian, Cortana could have found a way into the Domain, even though it had been locked away from the Forerunners. She hasn’t been able to communicate to Chief because once inserted into the Domain, she loses contact with the outside world, so to speak. Now that the Domain is open again, with the rise of the Guardians, she is able to communicate and does so to Master Chief.

Any one of these three has at least some plausibility to them. Maybe not entirely, maybe parts of them combined. We’ll have to wait and see. I am definitely intrigued to find out how Cortana is back and in what capacity.

What do you think? Like any of my theories? Have a theory of your own? Reply below!

-Sal