When Aaron Lightner brings Merrick to the Talamasca Motherhouse in New Orleans, Mary is one of his assistants in the Order who helps Merrick situate herself and acclimate to the hospitality of the Motherhouse’s environs. Mary lives in the Motherhouse and accompanies Aaron on some of his excursions with Merrick.
Mary appears in Merrick (2000). For more perspectives on Mary’s character, read the Alphabettery entries Aaron Lightner, Merrick Mayfair, and Talamasca Order.