Why Arbiter Wasn’t Infected by the Flood

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Every now and then I see something really good come out of Reddit. This debate has been floating around for awhile, but I’d like to propose a theory that makes a lot of in-universe sense and has significant information to back it up.

From a meta standpoint, it’s because Arbiter is a protagonist with plot armor. Just breathed in a cloud of Flood spores exhaled by the Gravemind itself? No negative side effects. Obviously, this is because Bungie probably didn’t want to introduce a friendly Elite that tips the audience’s perception of the Covenant on its head, just to turn him into a mindless combat form.

Some popular theories are that either A), his armor had some filtration system, like his energy shields (but this only works if you assume Arbiter’s shields never fell throughout any of his Flood-fighting missions, or that he had some smaller shields dedicated to filtration), or B), the Gravemind purposely doesn’t infect Arbiter so that he can assist it later. This doesn’t make sense either: why not put some dormant spores in him, then activate them once Tartarus is dead?

The most likely answer is remarkably simple, and kinda obvious when you recognize it:

The Delta Halo teleportation grid doesn’t allow Flood.

So when Gravemind threw Arbiter through the portal at the beginning of Uprising, all the Flood spores he had inhaled up to that point were wiped from his body.

There’s evidence to support this: despite having access to the teleportation grid, the Gravemind never used it to throw infection forms directly onto High Charity, needing instead to hijack In Amber Clad and use its slipspace drive to get Flood on board. The Gravemind couldn’t even use it to teleport Flood from one part of the Quarantine Zone to another. If that’s not sufficient alone, there’s a section in https://www.halopedia.org/Teleportation_grid that states “The fact that it (Gravemind) did not, or could not, use the same grid to teleport its own Flood combat forms to those locations indicates that use of it is restricted to non-Flood life forms and constructs.[16]”. So per this function of the Ring, any spores in Arbiter’s bloodstream would logically be either destroyed or left behind.

Here below is the original,