Ally suffered a breakdown after the 9/11 terrorist attacks in New York City. She claims that Ivy got her through her troubles and helped her eradicate the fears that she gained.
Personality and Appearance
Ally is a good person but is consumed by anxiety which often resurfaces after important events that negatively affect her life. When neglecting to take her medicine, she can be seen hallucinating which causes her absolute panic.
Ally suffers from coulrophobia, a fear of clowns, and trypophobia, a fear of irregular clusters of small holes. Her hallucinations reflect her fears, as she often sees menacing clowns or bleeding holes in food during episodes. She has expressed discomfort with a piece of coral to her psychiatrist.
Ally usually wears casual but trendy clothing and has her hair cut to a medium length. She is negatively affected by forces beyond her control, as evidenced by her near-hysterical fear in the wake of Donald Trump's win in the 2016 US Presidential Election. Ally is an avid liberal, professing her pride for Barack Obama. However, in the 2016 Presidential Election, she voted for Green Party candidate Jill Stein, stating that she "did not trust" Hillary Clinton.
After the election of Donald Trump as President of the United States (POTUS), Ally suffers from the resurfacing of multiple phobias including a fear of clowns and a fear of holes. Her therapist, Dr. Rudy Vincent, believes that she should take medication and disconnect from social media in order to discontinue her anxiety about the election or any other event she has no power over. However, Ally avoids taking her medication and suffers a series of hallucinations in the form of a group of clowns intending to kill her. When the hallucinations happen again at The Butchery on Main, Ivy realizes that Ally is not taking her medication and forces her to take them. 
Meanwhile, the Mayfair-Richards lost their housekeeper/nanny. Ally and Ivy are forced to find a replacement. The women hire Winter Anderson who assumes the role of babysitter for Oz. On the same evening, Ivy and Ally come home to find that their neighbors, Thom and Marilyn Chang, were murdered in a home invasion. However, the case is declared a murder-suicide. Oz claims to have seen the crime scene with Winter who dismisses Oz's statement as false. Later that night, Ally is attacked by one of the clown assailants in her bedroom.  She runs to Ivy distressed, but when they go to investigate the clown disappeared. The next day, Ally investigates the deceased Chang's former when she sees a new tenant and runs back home. Winter takes Oz to greet the new neighbors without Ally's and Ivy's permission; they cross the street and are introduced to Harrison Wilton and Meadow Wilton. Wilton shows them the honeycomb which triggers Ally's trypophobia. As they get ready for bed, the alarm for the restaurant is triggered. Ally decides to go and check, there she found Roger, one of their employees, dying in the cold room. Facing another breakdown, Ally became overly paranoid and decides to reinforce doors and windows with railings. Borrowing a gun from Harrison to ensure her family's safety, leading her to have a disagreement with her therapist. Ally receives a visit from Kai Anderson, Kai tries to intimidate Ally, but the two are separated by the gate on the front door. Winter takes advantage of Ally's delicate mental situation and ties to Ally with red wine and a hot bubble bath (promising not to tell). A blackout occurs and triggers panic in the neighborhood. Ally is once again attacked by a clown during the blackout and decides to flee her house with OZ. As they are about to exit the house, Pedro arrives with supplies Ivy asked him to deliver. Unfortunately, this startles an already petrified Ally and she accidentally kills Pedro.  Under Michigan's Stand-your-ground law, Ally is not charged with the murder of Pedro Morales by Detective Jack Samuels. This, however, puts Ally at the center of media attention. Activists picket the restaurant, accusing Ally of racially-motivated homicide, her neighbors go crazy and threaten Ally, saying that they want her out of "their" neighborhood. The situation becomes even more bizarre when a prank advertisement leads a voyeur to show up naked and masturbating at their house. Ally later faints due to a suspicious van spreading green smoke in the neighborhood. The Mayfair-Richards family enjoy a moment of peace at the restaurant, agreeing to keep Oz's new pet guinea pig, Mr.Guinea - given as a peace offering from the Wiltons, only to discover that the guinea pig had been placed in the microwave and explodes as they enter their home. Infuriated by the idea of being targeted, Ally confronts the Wiltons. Oz finds a video on his computer showing the intimate moment Winter and Ally had shared earlier, sparking an argument between Ally and Ivy. The argument is briefly paused when a hysterical bloodsoaked Harrison accuses Ally of murdering Meadow. 
- Ally Mayfair-Richards is the ninth character portrayed by Sarah Paulson in American Horror Story.
- In chronological order they are: Billie Dean Howard ("Murder House", "Hotel"); Lana Winters ("Asylum", "Roanoke"); Cordelia Foxx ("Coven"); Bette and Dot Tattler ("Freak Show"); Sally McKenna ("Hotel"); the re-enactment of Shelby Miller and Audrey Tindall ("Roanoke").
- She is the third LGBT+ character portrayed by Sarah Paulson, the first being Lana Winters in "Asylum" and "Roanoke", and the second being Sally McKenna in "Hotel."
- In the seventh season, Ally and Ivy are married and own a restaurant called The Butchery on Main, and if Ivy's promotional poster is any indication, they might not just be serving burgers. 
- Although at the panel for "The Women of American Horror Story: Cult" held at the FOX Studios it was revealed that Ally is married to Ivy, Ryan Murphy had previously revealed a "love story for the ages" between Ally and Kai, Evan Peters' character. 
- About the situation, Sarah Paulson simply said: "I think it’s going to reveal itself in surprising ways." 
- It's possible that Ryan Murphy's statement was a joke about the two as archenemies.
- As revealed in one of the pre-season clues, she suffers from several phobias; Coulrophobia, the intense terror of clowns, hemophobia, an extreme fear of blood, and trypophobia, extreme anxiety at the sight of irregular patterns or clusters of small holes or bumps. 
- Ally's phobias are based on Sarah Paulson's real-life phobias.
- In "Mid-Western Assassin," it was revealed that Ally was the one who gave birth to Oz due to Ivy's endometriosis making her unable to.
- In "Great Again" she turns down an interview with Lana Winters.
- In "Great Again," it is implied Ally is a SCUM member by the use of the word "man-splaining" and the black hood which all the SCUM members wear.
- She is the only main character to survive the season.
- To Ivy: "I can't do my cooking breathing."
- Ally (to Oz): "What are you reading?"
Ally: "Ozzie. Come on, honey. A picture of a bare breast or an erect penis never hurt anyone."
- To Ivy: "I know what I saw!"
- To Ivy: "I think there might be something wrong with me. I don't know what's real anymore."
- To Dr. Rudy Vincent: "The world is fucked up."
- To Oz (about Oz's guinea pig): "Sweetie. Come on. You know we don't like cisnormative pet names."
- To Meadow and Harrison: "I am not going to roll over and take this anymore. I am done telling myself to calm down, that I am damaged, crazy. I am not crazy and I am not weak! You people are terrorizing my family, and it stops now!"
- To Kai: "I'm not afraid of anything anymore."
- Ally (to Ivy): "I realized that those fears were filling a hole I had inside me, and you can't take those fears away without filling with that hole with something else. So I chose revenge. On you."
Ally: "You tried to make me go crazy. You tried to take my son away. You let yourself be seduced by the babysitter. And worst of all, you let Kai into our lives. And I couldn't forgive you for any of it."
- Ivy: "Oz will never forgive you."
Ally: "No, it's you he won't forgive, for abandoning him."
- To Ivy: "I only want two things in this life: I want Oz all to myself... and I want to watch you die. Halfway home."
- ↑ In Valerie Solanas Died For Your Sins: Scumbag, she appears in a footage
- ↑ 2.0 2.1 2.2 Episode: Neighbors From Hell
- ↑ Episode: Election Night
- ↑ Episode: Don't Be Afraid of the Dark
- ↑ Vanityfair.com, Here’s Everything We Know So Far About AHS Cult: Clowns, cannibalism, and fear.
- ↑ Murphy reveals on Instagram a love story between Ally and Kai
- ↑ Variety.com, ‘American Horror Story: Cult’ Will Focus on ‘What’s Going on in Our World’
- ↑ Ryan Murphy on Instagram, "All phobias in one" clue.
- ↑ |The Ellen Show, Sarah Paulson's Real-Life Phobias Were Written Into 'AHS: Cult'