To be clear, FX's Legion would never be mistaken for a horror series; it's a superhero origin story, albeit a strange one. Through three episodes, it's been difficult to discern what events happening to David Haller are real — the result of his mutant powers, paranoid schizophrenia or both.
But Legion does have some terrifying moments, and at the center of them is the "Devil With Yellow Eyes." He's the bulbous, yellow-eyed, um, thing, that has been haunting Haller's consciousness. However, he could also be a tangible threat to others around him — Haller's girlfriend Syd sees him briefly when she takes a trip through Haller's memories in episode three with Melanie and Ptonomy. Suffice it to say, if that demon was pursuing you through a claustrophobic air vent, you'd probably shit your pants.
Legion happens to be one of the scariest things on TV right now, with the aforementioned yellow demon and the repeated use of a Babadook-esque children's story about an angry boy chopping his mother's head off (the boy in question looks like a riff of Michael Fassbender's Frank with his enormous head). The creepy boy is unquestionably a figment of Haller's imagination, but what about the yellow demon? Here are some theories about who the villain could be, and how he might relate to the X-Men universe.
A superhero show as obscure as Legion deserves an antagonist that fits its zany narrative, and what better choice than a comic book villain few people are familiar with?
Mojo isn't a bad guy specific to Haller's Legion, but he is an X-Men villain who could serve a sardonic purpose if he's on the series. You see, the demon has the characteristics of Mojo — namely, his yellow skin and doughy shape — but what makes Mojo especially entertaining is that he presides over an alternate reality called the "Mojoverse." In other words, none of the events in Legion could be shaped in reality.
The idea of Mojo and the "Mojoverse" was the result of the character's creators, Ann Nocenti and Art Adams, spoofing media corporations, though it also doubles as an entertaining satire of our insatiable interest in reality television. If we're to believe Mojo is the main villain of Legion's first season, the show's big twist would hinge on the fact that nothing happening to Haller is real.
The Shadow King
The Shadow King doesn't look like the yellow demon — at least in the comics — but his psychic powers are perfectly suited as Haller's antagonist. In one of the comic book stories, the Shadow King even takes over one of Haller's alter egos.
If the Shadow King is Legion's villain, then the unsettling images of the yellow-eyed demon could act as a metaphor for Hallow slowly losing control of his own mind through some external, malevolent force. After all, whenever Ptonomy had issues traversing through his mind, Haller insisted he wasn't interfering. Maybe that's because there's someone else in play.
He's one of Haller's personalities
Legion has been described by its producer Lauren Shuler Donner as a "deconstruction of a villain," and in the comics, Haller does become a villain somewhat inadvertently. It's through a combination of his immense powers he can't fully control, coupled with his multiple personalities.
In other words, the yellow demon isn't its own character, but rather, one of Haller's personalities — in the same way that Haller's friend Lenny becomes part of his consciousness after she dies. It's also worth mentioning that other characters we've seen in Legion could also be a figment of Haller's imagination. Really, who's to say that Syd is real too?
However, until we get more definitive answers, the "Devil With Yellow Eyes" will continue to provide Legion's fan base with nightmare-fuel. So, uh, see you next week?
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