'American Horror Story': Everything We Know About Lily Rabe's Sister Eunice

Lily Rabe as Sister Mary Eunice in 'AHS: Freak Show'

As promised, another American Horror Story veteran will return in this week's Freak Show winter finale, and it is nun other than Lily Rabe.

Her return is not especially out of the ordinary — she's appeared in every installment of the show, and returning players is kinda AHS's thing — but what is special is that she is reprising her second-season character, Sister Mary Eunice.

If memory serves, the only other character to physically appear in two seasons is Pepper (Naomi Grossman). Probably not a coincidence, as the reason for Rabe's being back in the habit is actually the playful pinhead. We've been led by the show's creators to believe that her visit to the Florida freak show in 1952 will somehow set up how she winds up in Asylum's titular church-run sanitarium, Briarcliff, in Massachusetts in the mid-'60s.

Related: A Look at the Real Freaks That Inspired 'American Horror Story' Season 4

"Every season is its own, its own journey … [but] they're all connected. We're just beginning to tell you how," executive producer Ryan Murphy told Entertainment Weekly. "Lily coming back and dealing with Pepper is sort of the first unveiling of that connectedness. Season 2 is connected to Season 4, which is connected to Season 1. There's definitely a rhyme or a reason and a connectedness. There [are] clues every season that tell you how the different worlds are intertwined."

Murphy was lucky that Rabe could take time out of filming her part as the female lead in ABC's The Whispers, an upcoming supernatural FBI thriller produced by Steven Spielberg, to make an appearance. "I understood she wanted to go off and do her own show, but I was thrilled she was able to come back, give us a couple days, and show how Sister Mary Eunice and Pepper are connected. She's so great in that role."

Lily Rabe as Sister Eunice in 'American Horror Story: Asylum'

Given the revelation that all seasons are tied together somehow, we thought you might need a refresher. Here's what we already know about the good sister from our earlier introduction to her future self before we meet her and Pepper in the past this week.

* The Catholic Church purchased the old tuberculosis hospital in 1962 and repurposed it as a mental institution, which was run by Monsignor Timothy Howard (Joseph Fiennes) and administrator Sister Jude (Jessica Lange) until 1965. Sister Mary Eunice was essentially Jude's right-hand woman.

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* Devout and dainty, Sister Mary cowers before authority figures Sister Jude and Dr. Arden (James Cromwell) despite silently questioning their tactics at times. She is innocent (she described an incoming alleged murderer as "the bad person"), insecure, and fragile. This might stem from a trauma she experienced as a teen. She attended a pool party where she was stigmatized by a classic skinny-dipping prank that left her exposed literally and figuratively.

* She was the one who led reporter Lana Winters (Sarah Paulson) through the asylum to meet with Sister Jude about a story. Along the way, Pepper tried to befriend Lana with a flower and a request to play. Sister Mary warned Lana that Pepper was "anything but harmless," as she had been convicted of drowning her sister's baby and cutting off his ears. (Pepper later denied the crime.)

* While out feeding Dr. Arden's creepy woodland creatures, Sister Mary was tricked into helping Lana sneak back into the hospital. She easily admitted to her part in the plot and basically begged for punishment, draping herself over Sister Jude's desk and requesting a hard spanking. She fears and craves the nun's iron fist.

Lily Rabe as Sister Mary Eunice and James Cromwell as Dr. Arthur Arden in 'American Horror Story: Asylum'

* When Dr. Arden offered her a sugary snack, she declined, saying, "No, I really shouldn't. Sister Jude said sweets lead to sin."

* At some point in the second season, she was possessed by a demon and turned into a sly, manipulative, crass, sexed-up, and evil version of herself. The devil made her do many things, including killing a few patients, framing Sister Jude, and raping the monsignor. The last act took away her virgin Mary status (which we'll assume is intact in the new Freak Show episode). After Sister Mary took over the cuckoo's nest and wreaked havoc on everyone's lives, a brief flash of the real Eunice reclaiming control of her mind and body and begging for the monsignor to end her suffering allowed him to toss her over the stairs and send her and the unholy spirit to their death.

Watch a deleted scene featuring Rabe and Fiennes from Asylum:

American Horror Story: Freak Show airs Wednesdays at 10 p.m. on FX.