General Protection Fault/WMG

Sidney Duncan is "The One".
Not Fooker and Sharon. They will influence Sid, though.

Fooker, post dimensional raid
Fooker is controlled by a Puppeteer Parasite. Specifically, he doesn't like being around Fred soon after the raid, and barely held fire against Persephone.

Fooker found out something during the dimensional raid.
Something the greys already knew. Fred and Persephone aren't mutated slime molds. They're aliens. Good aliens, but with evil counterparts in the other dimension. That mysterious thing that keeps calling them is another of their species, trying to jog Fred's memory because he has Laser-Guided Amnesia. (I will be genuinely surprised if this is jossed, it seems so obvious.)