Marie was a student at a girls' school in Flint, Michigan who created a "Supernatural" fan fiction musical.
Unsatisfied with Carver Edlund ending Supernatural with Dean quitting hunting to live with Lisa and Sam mysteriously back from Hell, she decided to create her own "transformative" fan fiction in the form of a play.
However, her play attracted a scarecrow who proceeded to kidnap everyone who tried to cancel the play. She witnesses the kidnapping of her friend Maggie left shaken by the experience, and Maeve tends to her by serving her coffee. Marie admits the police didn't believe her stories, blaming it on "overactive imagination". Maeve tells Sam and Dean she wants to believe in ghosts and demons, and Sam and Dean encourage it, since those things are real and reveal they are the Winchesters.
The girls accept monsters are real, but seemingly deny any possibility that Sam and Dean are the real ones because they are too old. Maeve compares them to Bobby and Rufus. When Sam suggests the scarecrow was based on her version of a scarecrow, the four come to the conclusion that they're dealing with a tulpa. However, their suspicions are proven incorrect when evidence confirms that the culprit is in fact Calliope. Marie is worried and gets scared when she hears she'll be eaten after the play is done, she tries to cancel the play but is told that won't stop the deity. Marie was further worried after Dean said the show must go on.
After gathering her wits, Marie took the role of "Sam Winchester" in the play, replacing Maggie. When the Scarecrow appeared, Marie witnessed it take Sam away and kept performing at Dean's request. Marie watched as Dean fought the creature, which soon tossed him aside and focused on her. She takes the stake and stabs it in the chest, while at the same time Sam found and killed Calliope. Because of this, the audience loved her play and she was pleased with the results.
Marie later gave Dean a fake amulet to replace the one he threw away, while hinting she now believes he is who he says, to his surprise. She sung "Carry On My Wayward Son" at the end of the performance.
Later that day, Maeve told Marie someone claimed the publisher's ticket. Marie then met Carver Edlund, excitedly asking how it was as he praised her work, calling it "Not bad".
- Marie revealed to Dean that she is a Sam-girl, believing Sam to be brave and selfless.
- It appeared after the play she now believed Dean and Sam were real as she gave Dean a replica of Dean's Amulet and criticizes him for throwing the original away.