Big spoilers for "Halo 5"are included in this one, people. If you have any interest in playing the campaign but have not done so, avert your eyes immediately!

For those of you who have seen the latest "Halo" game through to the end, it’s pretty safe to say that the galaxy has gone to hell in a hand basket. Cortana has control of the Domain and the Guardians. The Master Chief and his allies are left powerless. The Reclamation has begun.

This is going to focus on Cortana herself. She has been a fan favorite since the series’ inception and it's probably because she is one of the most relatable and human characters despite her artificial birth. Well, she was until she went all batty and claimed the Mantle of Responsibility for herself and her fellow Created. This apparently less-than-favorable plot twist was quite out of left field, even by "Halo"standards.

Many speculative theories have arisen since the release of "Halo 5," and they all sound quite interesting. Some say she's not the “real” Cortana, but rather a rampant splinter intelligence left behind in the Domain after the events of "Halo 4." Some say her contact with the Domain caused her to assimilate with the intelligence of one 343 Guilty Spark, or some other Monitor with similar attributes. But I’m willing to bring forth my own theory to the table, and it involves (albeit nominally) one very ancient and dire threat.

The Flood.

This theory sort of tickles the brain in the sense that Cortana was always intended to devolve into a threat against civilization. It dates all the way back to "Combat Evolved."

In the first game, the player witnesses a heated argument between Cortana and 343 Guilty Spark. Consider their arguments: Cortana wants to destroy Halo, sparing the rest of the galaxy and preventing the Flood from escaping the ring, whereas Spark wants to activate the ring, exterminating the Flood but wiping out all sentient life in the galaxy as a safety precaution. Cortana is choosing the riskier option, which saves the most lives and renders a firing of the Halo Array to be an irrational oversight. Her inherent disdain for the Forerunners begins here, and this creates a very telling similarity between her and the Precursors.

343 Guilty Spark

This ancient race precedes the Forerunners and later evolves into the Flood after they are nearly driven to extinction. Guess who tried to make that happen? You guessed it – the Forerunners. The Flood has a personal, collective mission to assimilate all sentient life into its fungal hive mind, resulting in one species across the universe and depriving it of free will.

Moving on to "Halo 2," when the Covenant Holy City of High Charity is completely overrun by the Flood, Cortana is left behind to have a little chat with the Gravemind, the collective intelligence of the Flood. Keep in mind – we have never discovered exactly what information Cortana has surrendered to the Gravemind, and it obviously did a number on her matrices, as evidenced by her recovery by the Chief in "Halo 3." She claimed that “so much of her was wrong… out of place.” I would argue that this is the true start of her rampancy that we experience in "Halo 4." This makes it an abnormal rampancy for two reasons: it began years prior to her expected decay stage, and it was likely caused by a foreign intelligence, possibly some form of a Flood nervous tap.

In "Halo 4," we also see Cortana subdue the Didact despite her crazed state. The centuries-old Forerunner mistook her aid of the Chief as a token of compassion for humanity, but Cortana was quick to denounce the notion. So, we see Cortana revisit this disdain for the Forerunners and their incessant need to “cleanse” the galaxy, but we also see Cortana’s first instance of resentment toward her creators.

Finally, we have the megalomaniac with the blue hair (and… well… everything else…) running the show at the end of "Halo 5." Her doctrine is made clear: she wants to police and unite the entire galaxy under the singular banner of the Reclamation and her Created. Those who step out of line will suffer. Let’s see, a single collective intelligence controlling every sentient species and depriving them of free will… sound familiar?

Although it may not be the actual parasite in play, Cortana is enacting the will of the Precursors and the Flood with her bastardization of the Mantle of Responsibility. She has been corrupted by the Gravemind's Logic Plague, much like 032 Mendicant Bias before her, and further strengthened by the greatest technological stronghold in the known galaxy. The worst part is, the Legendary Ending of "Halo 5"reveals Cortana humming as a Halo ring comes into view. Many fans have speculated that this is Installation 07, supposedly known for its unprecedented supply of Flood research facilities, complete with dormant, living specimens.

The fact that the planet is a putrid Flood-green makes this even more unsettling.

Imagine Cortana releasing the Flood from this ring just to spite her enemies. After all, the Flood cannot infect her or the Prometheans. If all of this comes to fruition, it means only one thing -- we are in for a whole galaxy of hurt.