A high-ranking member of Ouroboros and one of the newst additions to the society.
As a member of the Crois family, she was involved in the project to recreate the Sept-Terrion of Mirage. As such, her knowledge of alchemy and sorcery are unmatched. In addition, she served as CEO of the International Bank of Crossbell for a time.
Though she used KeA, a homunculus created by her ancestors, to successfully create the Sept-Terrion of Zero, after Lloyd and the SSS saved the girl, Mariabell decided to let things be and left Crossbell.
Afterward, she was invited by the Grandmaster to join Ouroboros as the new Third Anguis. As the curse falls over Erebonia, she makes her return to her former home...