I’ve got another idea for you all to chew over regarding the Flood. Previously I surmised that the Flood, particularly the Gravemind, would make Chief believe Cortana had returned and trick him into accomplishing its ends. It does have the ability to create hallucinations that are very convincing. This time around, I believe the Flood may be able to turn the Spartan-IVs against the Chief without infecting them. Here is what I’ve got.
First, let’s get some insight on the Spartans themselves. Halo 4 showed us that the Librarian planted the seeds for the development of the Spartans, MJOLNIR and AIs like Cortana while Halsey was the human who brought these creations into existence. Near as I can tell, this was done in order to make humanity more like the Forerunners. Forerunners had advanced armor with AIs housed inside, the Spartans have advanced armor systems that later were given the ability to house an AI. The biggest difference is that the Forerunner AIs were more like servants as opposed to humanities AIs who seem to be given more free-reign and are treated with more respect and dignity.
At this point, you can probably guess I am working my way towards the AI angle. I have a feeling that at some point before Halo 5/XBO, perhaps in Halo: Escalation, or during the events of the game, the rest of the Spartan-IVs will begin to get outfitted with AIs of their own. Where will they come from? I don’t know, but Cortana’s comment about Chief maybe getting another “Cortana-model” AI has intrigued me for a while. At first, it was confusion due to the fact there was no such thing as a Cortana-model AI, after all Cortana was a unique AI made from Halsey’s living brain tissue, most AIs from the dead tissue from donated brains. So perhaps the UNSC has found a way to mass-produce AIs for the Fours to augment their abilities and Cortana serves as either the template or inspiration?
If so, I think these AIs are going to end up dooming the Fours. Here is where the Flood comes in. The Flood has this effect on AIs, as demonstrated by the betrayal of the AI known as Mendicant Bias towards the Forerunners after conversing with the Primordial for nearly 50 years, where it corrupts them and bends them to their will. This is called the Logic Plague. It is my belief that the Flood may be able to hack these new AIs with the Logic Plague and control the armor of the Spartans and force them to fight against their will.
Does it seem far-fetched? Well, like the hallucinations I proposed Chief could experience in my last thread, there is prescient here. In the novel Halo: Primordium, one of the human characters named Riser is in the company of three Forerunners. They had crashed on a rouge Halo ring under the control of the Primordial and the Flood and were on their own. One Forerunner was locked in his armor while the other two are still able to move. However, the armor of the locked up Forerunner actually begins to squeeze him and crushes him to death. The other two Forerunners shed their armor, but even shed off it tries to kill them. It is my belief that the Flood’s Logic Plague got to the Forerunner AIs in their armor and started to control it for their own ends.
So there you have it. Like the Cortana idea, I feel having to kill these Spartans now under the control of Logic Plague AIs may cause some discomfort in players and the Chief. After all, the Spartans themselves aren’t trying to kill you, they are acting against their will. Another factor to consider is that it will ultimately hurt the plans of the Librarian and Halsey, both of whom were trying to accelerate humanities evolution.
Perhaps this wasn’t as compelling as the last thread, but I hope it gives you something to think about.

