In her time with the Sabbat, Marie-Ange Gagnon originally belonged to the La Belle Morte Pack, a pack of nomads that recruited new vampires into the Sabbat. This led her and her pack across the globe, until they ended up in China, where all other members of her pack were slain by the native supernatural creatures during the Boxer Rebellion. She returned to Montréal, the city of her birth, and joined the newly formed Librarians.
An expert on the inherent powers of vitae, Marie-Ange was plagued by dreams of the destroyed Setite temple of Montréal, leading her to find the torpid body of Sangris the Serpent, an infernalist. Sangris slowly corrupted her thirst for knowledge, turning her into his tool to reawaken him.
Marie-Ange is a beefy, rugged, black-haired woman who dresses in comfortable work attire. She uses Vicissitude to bring her veins to the surface of her skin, making her look like a pulsating road map.