FX’s Legion, considered a loose X-Men spinoff, has its David Haller.

The show will feature Dan Stevens (Downton Abbey) in the titular role of Haller, who is the estranged son of Professor X. Haller is a darker character in the X-Men universe, someone who doesn’t know if he has a severe mental illness, or is someone who simply possesses intense superpowers. In the comics, Haller was more of an antihero who had a dissociative identity disorder, with each of his personas controlling one of his many abilities.

The Legion pilot will paint Haller’s character as someone who is diagnosed as schizophrenic, but eventually comes to realize he has powers after an encounter with another patient.

The Hollywood Reporter says Aubrey Plaza, known for her role as April in Parks & Recreation, will play Lenny, a struggling alcoholic and drug abuser, and one of David’s good friends. Jean Smart will also join the pilot as Melanie, a therapist who utilizes unconventional methods. Rachael Keller was previously cast for the role of Syd.

Production on the show will kick off in March, which means we’re still in for a hefty wait before Legion officially premieres.