FX's upcoming superhero series Legion is about a character who first appeared in X-Men, the Marvel comics franchise.

In the comics, Legion, whose human name is David Haller, is an extraordinarily powerful mutant with multiple personalities. Each of his personalities has a different superpower. Sometimes it's less like he has multiple personalities and more like he's hundreds of different consciousnesses inhabiting the same body. He's an antihero — sometimes he works with the X-Men; sometimes he does his own thing. He's definitely mentally ill.

But Legion the series is a different kind of superhero show, and this Legion may not be the same as the one in the comics, especially in how his personalities manifest themselves.

Dan Stevens and Rachel Keller, <em>Legion</em>Dan Stevens and Rachel Keller, Legion

"It's not as explicit as some of comic books draw it," star Dan Stevens tells TVGuide.com, although it "depends which incarnation you look at."

Stevens says it won't be a version where all the personalities will be seen locked up in "physical fortress" fighting amongst themselves to be the dominant one.

"Depending on who's at the helm of controlling David's mind at any given point, the level of confidence with which he wields these powers kind of varies," he says.

"They're just starting to discover these abilities and things about themselves," adds Rachel Keller, who plays David's girlfriend Syd, who has some mysterious powers of her own.

"I think they're still kind of learning about how, practically, to live with these abilities," she says.

Legion premieres Wednesday, Feb. 8 at 10/9c on FX.