Murder House-"You'll come to understand, Violet, that the word 'ancient' will lose all its meaning when your entire existence is one long today."

It is claimed that to women she appears as an elderly lady with one working eye (the other is gray and clouded) and a sensible uniform dress but to men she appears as a beautiful, unscathed young woman with a short skirt and stockings. According to Moira, this is because women's intuition gives them insight on the true nature of people whereas men see only what they desire - however, if the man can resist the compulsion to see her as a sexual object, they too will see her as who she is.

In her senior disguise she is pleasant and professional. In her prime she is seductive and manipulative. As a person, she despises men as liars and cheaters, having met her end because of such a man. As such, she also sympathize with women who have been cheated on. She also has a deep desire to leave the Murder House, and is willing to kill or have killed anyone who will prevent her remains from leaving; the building of the gazebo and the burial of Hayden brings a deep despair to Moira.

Moira's knowledge of how to maintain the house impresses Vivien, the new lady of the house, enough that she is permitted to continue in her position. She begins a campaign of trying to seduce Ben. Vivien was unaware of just how long or deep Moira's connection to the house ran. Constance revealed, in passing, that Moira had worked for her before. Certainly, Moira was comfortable enough with the history of the house to bury bodies alongside Constance and Tate.

While still alive, she once had sex with Constance's husband, Hugo, due to "feeling lonely". When he made another advance towards her she refused him saying that what they did was a mistake. In 1983, not happy with being denied, Hugo forced himself on Moira and attempted to rape her only to be caught in the act by Constance. Constance shot Moira in the eye, and Hugo in the heart. Constance then buried her in the backyard of the house.

On Halloween 2011, Moira left the premises to visit her dying and comatose mother (Molly) in a long-term care facility. Moira felt guilty that she hadn't been there for her, and resolved to set her free. Moira unhooked the respirator, and her mother died. Molly's ghost bids that Moira should come with her, but Moira cries that she can't. She returned to the house shortly before sunrise.

Moira showed her dedication to Vivien when she reluctantly prepared the offal meals Constance brought for Vivien's babies. Around the same time, she shows resistance to the will of the house by seducing Joe Escandarian, so that he will buy the house and put in a pool, requiring him to unearth her body in the backyard (and hopefully release her trapped spirit). She was horrified to realize he intended to pave the land as a parking lot instead. She responded by biting off his penis during fellatio, and a team effort between Constance, Larry and Moira kills him off-site.

Moira urged Vivien to leave the house as soon as possible while she still could, fearing for Vivien's safety from Hayden and other influences. It was revealed that she helped to orchestrate the scene in which Chad Warwick and Patrick were found after their deaths.
Moira continued to try to seduce Ben during Vivien's committal, which he would still have none of. Exasperated, she and Elizabeth Short had sex on Ben's couch, and Moira tried again to entice him. He responded by firing her. She returned to find Ben holding the Rubber Mn mask, putting facts together. He rejected her one final time; convinced he truly loves Vivien, Moira congratulates him. She appears in her older form to him from that point on.

Moira cleans a newborn Harmon baby, and becomes the godmother to a ghostly Jeffrey Harmon when he is later discovered. She is considered an equal to them and a friend after their ordeal, and work to keep unsuspecting families away from the violent elements in the house.