Before the apocalypse, Mallory is a stylish individual who seems eager to help Coco establish herself as a social media influencer.
Following the apocalypse, Mallory is made to wear a dull, grey outfit and have her hair styled in a tall bun due to her position as a servant at Outpost 3. She is eager to be upgraded to purple status and feels left out due to the people she came with all being made purples.
Mallory is first seen at the hair salon where her boss, Coco is getting her hair done by hairdresser Gallant. Everyone's phones suddenly receive an emergency alert that a ballistic missile is set to impact Los Angeles and to seek shelter. Coco first dismisses it as a hoax, but her father calls her to tell her the threat is real and to get to Santa Monica airport where a private jet is waiting. Mallory and Coco run out of the salon and get into a car that is waiting for them.
On their way to the airport, Mallory tells Coco that she needs to go home as she can't get a hold of her mom, but Coco begs her to stay, telling her she would be lost without her and offers her her brother's ticket, to which Mallory agrees. As they arrive at the airport, Gallant and his grandmother [[Evie Gallant|Evie]
] show up. Mr. Gallant tells Coco that he heard her father say there were four spaces and that he and Evie are here to take the remaining two.
Onboard, Mallory goes to the cockpit to ask the pilots where they are going but finds that the plane is unmanned. Suddenly, the missile hits Los Angeles and the plane begins to rock violently, but it restores itself quickly. Coco, Mallory and Mr. Gallant look out of the window to see a mushroom cloud rising where Los Angeles has been destroyed.
A few weeks later at Outpost 3, Mallory has been put into servitude as a gray, waiting on the purples. Whilst serving mineral water, she asks Coco is she has spoken to Wilhemina Venable about making her a purple, but Coco tells her that she scares her and that Mallory doesn't have a good reason to be a purple like Evie and Gallant do.
When the song on the jukebox changes, Gallant believes this is a sign that The Cooperative are coming to rescue them. Mallory gets excited and drinks the mineral water she is serving to celebrate. However, eighteen months later the group have still not been rescued. When Gallant and Coco protest at dinner saying that they are fed up of waiting around to die, Mallory states that she thinks they should take their chances outside. However, Ms. Mead says that no one is going to leave. 
To Coco St. Pierre Vanderbilt: "It's not fair that they get to be Purples and not me."
Mallory is the third character portrayed by Billie Lourd. For a complete list of her characters, see Cast.
She's one of the first characters of Apocalypse to have been confirmed.