Mariah was a young black woman in a small, racist Texas town where Brandon Walsh's car broke down as he was coming home for the summer. Mariah had an affection for angels and wanted to travel from the small town where she worked as a librarian to the big cities so that she could become an author.
As she and Brandon spent time together, the locals began harassing them with racist remarks. As Brandon and Mariah spent time together, she quizzed him on the outside world, eventually inspired to leave Hadley City and go to New York. They shared a kiss goodbye before Mariah boarded the bus and left the little town.
Mariah later came to Los Angeles for a visit. By then, Brandon was caught in a love triangle between Tracy Gaylian and Kelly Taylor. She gave a speech about angels at California University, which many of the group attended. Mariah clearly favored Kelly over Tracy and her presence served as a catalyst for Brandon and Kelly getting back together. She later returned to New York.