In "Soos and the Real Girl," Mariah is seen watching Hoo-Ha's Jamboree perform live, and she tips Will E. Badger, telling him that to take all of her money. She is later seen running out of the restroom when Mabel charges in, yelling at the women that "it's love time."
Mariah is a young woman with fair skin and short, light brown hair. She wears a lavender, deep V-neck with an undershirt, faded jeans with a rip on the right knee and white and lavender converses.
In her concept art her hair is a brighter shade of brown and more curly. Her shirt is a navy blue and has no V-neck, she wears a green necklace, her jeans are ripped, and are a slightly darker shade of blue and she wears white and dark gray converses.
- She is based off of and voiced by Mariah Amundsen, who visited the Gravity Falls production offices via the Make a Wish Foundation.