Just over two weeks since its debut, the phenomenon of making theories about The OA has risen to the level of a sport, similar to the legions of fans who spend hours trying to figure out which characters are really in Elliot's head on Mr. Robot or trying to discern which characters are really robots on Westworld. The metaphysical Netflix drama has inspired reams of digital ink devoted to solving the mysteries of Prairie Johnson, aka the "Original Angel." But if this theory about the FBI on The OA is true, it could potentially connect several disparate speculations into one unified theory that actually explains a lot about the show.
By now, most viewers are in agreement that FBI counselor Elias is up to no good; he certainly had no business being in Prairie's house when she wasn't there, at night, without the lights on. One widely accepted theory claims that Elias planted the box of books underneath Prairie's bed in an attempt to discredit her story. After all, we saw her googling Homer's name long before she would have had a chance to order that literature — and when would Prairie have learned to read printed English, anyway, if she only grew up reading Russian and Braille?
A second, lesser known theory centers around Rachel and her role in Prairie's story. After her introduction, where we learn that she's a great singer and she tells her fellow captives the story of her Near-Death Experience, we don't really learn much about her. She never even receives one of the five Movements (the final one comes not from her, but from the sheriff's wife), which has made many fans wonder why she exists at all. But as Reddit user NullAndNil points out, the braille on the wall of the FBI office reads "Rachel," leading some viewers to speculate that Rachel is actually an undercover FBI agent.
While those theories about Elias and Rachel make sense in terms of the evidence, the biggest question for both remains: why? Why is Elias trying to discredit Prairie? And why is an FBI agent in Hap's basement? While it's possible that the FBI was already investigating Hap's scientific misconduct and sent Rachel to infiltrate his experiments, there's another alternative that could potentially make even more sense: Hap knows about Rachel's true nature because Hap and the FBI are in on the experiments together.
Think about it; given how illicit and illegal Hap's experiments are, he's clearly not getting any funding from legitimate sources. So, unless he happened to be the inheritor of a Bill Gates-sized fortune, how did he possibly afford the elaborate set-up in his Bond-villain basement lair? If the answer isn't "from the government," then that's a lingering question that definitely needs to be answered in Season 2.
Assuming that Rachel is an FBI agent, her presence in the basement actually makes even more sense if Hap knows the truth. Not only does she never receive a Movement, but we never even see Hap take her out of her cell for experiments like Prairie, Homer, and Scott. (We never see Renata undergo the procedure either, but we know she must have at some point, since she received a Movement.) Rachel could have been planted there to spy, not on Hap, but on her fellow captives, catching any and every exchange between them that Hap might miss. And, of course, every proper experiment should have a control subject.
Once Prairie escapes and becomes a media sensation, it makes sense that the FBI would immediately set out to discredit her. They can't have anyone believing in her story about metaphysical science experiments if any of it could end up being traced back to their agency… which is why they assign Elias to gain Prairie's confidence, learn what she's telling people, and launch an effective smear campaign against her story.
The question is, what exactly is the FBI's investment in Hap's experiments? Given how shocked Hap seemed to discover the Movements' healing capabilities, it seems unlikely that the agency's interest was medical in nature. More likely, the FBI is interested in harnessing the NDE survivors' ability to open inter-dimensional portals for some nefarious, possibly militaristic purpose.
Whatever the FBI's interest, this theory certainly explains a lot: Rachel's presence, Elias' actions, Hap's funding. Hopefully we get more answers about the FBI's role in Prairie's imprisonment when The OA (hopefully) returns for Season 2.