These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
The Devil itself is called up in a failed exorcism and possesses an innocent young nun, driving her to uninhibited and lewd behavior as a start. The Devil begins murdering other inmates and sowing the seeds of chaos around the Briarcliff Asylum, solely For the Evulz. When it learns that the resident doctor is really a Nazi war criminal escapee, it's actually excited and murders a concentration camp survivor who might expose him. The Devil later confronts the Monsignor about his rather un-priestly ambition and to top it off, rapes him despite his vows of celibacy, solely to debase him.
The Serial Killer Bloody Face, AKA Dr. Thredson, is a killer of women who takes their skin and teeth and later frames an innocent man for his crimes. After killing the lesbian lover of the heroine Lana, Bloody Face keeps the corpse on ice to "help" with Lana's therapy, luring her into his home so he can hold her hostage and rapes her multiple times before trying to kill her. After her escape, she ends back in Briarcliff where he attempts to assert his hold over her again and eliminate her there. When he learns she's pregnant, he seems to relent, but when threatened he decides to murder her again without a trace of remorse and gloats to her before the attempt how he'll never see a day in prison with the insanity defense.
Leigh Emerson, another Serial Killer, murdered multiple families on Christmas while dressed as Santa Claus, children included. After the Devil frees him in Briar Cliff, he shows utter eagerness in resuming his rampages and attempts to rape Sister Jude. He manages to successfully pin the incident on her, presents himself as wanting redemption and convinces the Monsignor to baptize him, only to nearly drown him and crucify him before leaving to resume his murders outside the asylum.
Fan Nickname: For the series itself, there's "American Horror Story: Assylum", due to the many, many ass shots in the show between the cane-ings and the clothing the prisoners wear, among other things.
Lana Banana, for Lana based on what Sister Jude said when they first met. Seeing as how Lana's the Woobie, it works well.
The show is also being called "American Whore Story", thanks to Dr. Arden's exclamation of "Whores get nothing!"
Foe Yay: Sister Mary Eunice has this with just about everyone, particularly Sister Jude.
Les Yay: A small amount between Sister Mary Eunice and Lana.
Most Annoying Sound: The music that plays in the common room ("Dominique-inique-inique s'en allait tout simplement..."). Kit has attacked the record player more than once, just to get it to stop. It finally dies when Jude shatters the record, and is replaced with a much more tolerable jukebox assortment.
Most Wonderful Sound: The season ends with a flashback to Lana and Sister Jude speaking (rather civilly) as the former is about to leave the asylum (this is before she came back and ended up incarcerated for her trouble). The same song as above is playing, and after all the dreadful happenings the viewers have seen, it feels strangely peaceful.
Narm: Sister Mary Eunice is walking narm, what with her constant blubbering.
Dr. Arden puts lipstick on a statue of the virgin Mary, yells "whore" at it for a few minutes, then pushes it over.
Thredson: "Baby needs some colostrum." Doubles as Squick.
Dr. Arden's real name is Hans Gruper. It's kind of hard to establish tension when one of your characters' name sounds like a character from Die Hard.
The scene where Dr. Arden attempted to rape a prostitute would have been much more horrifying without the straight-faced delivery of the line "Show me your mossy bank."
Spoiled by the Format: The second season was announced to be running for 13 episodes even before the first had aired; however, this effectively spoils that a good amount of plot has yet to go, despite several story arcs being tied up by Episode 11/Spilt Milk.
Squick: Doctor Arden cuts into Kit's neck. An alien chip crawls out.
Sister Eunice stabs a patient to death with a pair of scissors.
And then Doctor Arden cuts off Shelley's legs. We thankful don't see this operation (our wonderful imaginations get to paint that picture for us), but we do see the aftermath and it... well, it's not pretty to say the least. Are we starting to see a pattern here concerning Doctor Arden?