> Cortana learned about the Ark from the Gravemind, and presumably also that a replacement for installation 04 (which got blown up in H:CE) was being build there. Since the Gravemind needed to deactivate the whole Halo array in order for the Flood to spread through the Milky Way without any noteworthy resistance, she knew that he’d eventually go there. And knowing Master Chief, she counted on him firing the replacement ring at the Ark to wipe out the Gravemind and all the Flood remaining aside from those trapped on installation 05, i.e. Delta Halo.
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> And yes, there are more Flood in the galaxy. First of all, there are those Flood who didn’t go to High Charity but remained on installation 05. They’re basically trapped there since no ships capable of faster-than-light travel are left; they either got destroyed or managed to escape before being taken over by the Flood.
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> It’s also safe to assume that there actually are quite a lot of Flood left on the remaining Halo rings and also various other Forerunner installations likes the retrofitted gas mine above Threshold (which got destroyed by the Arbiter).
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> I’m just wondering, however, if and how we will encounter the Flood in H4. The Forerunners not only constructed the Halo array but also various shield worlds like Onyx or that planety thing Master Chief is traveling towards (or rather, falling down on) in the H4 trailer. It just stands to see if that thing actually is a shield world or something else. But if it is, it’s very unlikely that Master Chief will encounter any Flood there because they never were used to store Flood samples. At least as far as we know for now.
Although that’s really the only argument for her “quote”, it’s really not a satisfactory one to me.
For one thing, there was no guarantee the Ring would be ready to fire, not to mention the fact that firing it not only meant destroying every Sentient life form around it (Yes, it’s outside the edge of the Galaxy, but you better hope the portal is still open before you fire it) but also considering it wasn’t even finished, firing it meant physically destroying it and the Ark and possibly any hope of getting back in case you failed at preventing Gravemind from getting through the portal back to earth (before the ring went off).
Furthermore, destroying the Ark, and therefore the producers of the Rings, prevents any future last ditched effort in not only stopping the Flood in the worst-case scenario of the Flood overrunning all resistance in the Galaxy and having to fall back to the Ark for not only firing the Halo Array, but also ensuring the surivival of any species still stored at the Ark and any Species Representatives that are able to escape to the Ark during the last-ditched effort.
All it will take now for the Galaxy to fall is for one naive ship captain to pilot their vessel to an unknown forerunner facility/halo-ring that has flood spores on it, and for curiosity’s sake land, and then the calamity of the flood and it’s ever-growing presence starts ALL over again, and now you don’t have the Ark to fire the rings all at once and from a safe distance. Not a very good plan at all I must say. Last ditched effort yes, but a good plan, no.
Not only that, but I would think the Forerunners would’ve built into the gateway portal to the Ark, an ‘auto shutdown’ once a vessel or two traversed into it, to prevent the likelihood of a flood infested vessel of following through and the tainting of the Ark (Master Control/Haven for all species information/dna within the Galaxy). And yet, clearly we saw the portal remain open indefinitely in H3 (For obvious plot reasons, as it shutting down would’ve prevented Chief/Arbiter from following, and yet Truth would have just been sitting at the Ark’s Control Room pissed off beyond belief as he realizes he can’t activate the Great Journey without the convenient humans dropping in to stop him to provide a human helping hand, so to speak), which, beyond the obvious immeasurable and incalculable energy requirements needed to maintain the portal, would clearly allow the Flood to pursue their would-be exterminators to the very place that they shouldn’t be allowed to enter.
The plot-holes of Bungies Tale are unfortunately glaringly apparent when one begins to truly examine it, but such things aren’t to be viewed under a microscope intently without effectively destroying the illusion of a cohesive “masterpiece” and essentially seeing “the man behind the curtain”.