Mariabell's character and personality takes shape as a flashy rich executive with a sadistic side. She is Dieter's only child and has had a close friendship with Elie MacDowell since she was young. Fiercely protective of Elie, she vows to attack any man that would dare approach her romantically.
As the executive director of the IBC under her father, Mariabell had been entrusted with a number of enterprises and capable of serving as Dieter's stand-in. One of the significant tasks she was charged with was the development of Mishelam.
Crois family heritage
In the shadows, however, she committed herself alongside her father to finish the centuries-long plan to re-create Demiourgos, the Sept-Terrion of Mirage. Beginning in S.700, the Crois family secretly invested in ancient alchemy magic and the D∴G Cult to further this goal using their banking finances to replace the Sept-Terrion that had been lost.
Using her influence as project leader of Mishelam's development, she manipulated Hartmann into organising the Black Auction so she could have the core of the new Sept-Terrion awaken on Mishelam. Mariabell had Arios MacLaine replace one of the auction's items, a Doll Studio doll suitcase, with a suitcase that held the sleeping KeA so that KeA could awaken safely under her supervision without raising suspicion.
The Crois family had been working on the re-creation of Demiourgos for a thousand years together. However, in the final act of Ao no Kiseki, Mariabell abandons her father Dieter and his political ambition of using KeA and her powers to defend and expand Crossbell's control, replacing it with her desire to rewrite history itself.
Due to the heroic interference of the Special Support Section and their allies, the plan to alter history failed. KeA abandoned her powers and lost all value to Mariabell. Despite this setback, she was invited by the Grandmaster to fill in the position of third Anguis that had been vacant for almost two years due to Mariabell's knowledge of how to recreate a new Sept-Terrion.
- Mariabell is an big fan of the dolls made by the Doll Studio. Her collection of dolls is worth several million mira.
|Anguis||Vita Clotilde (2nd) - Georg Weissmann (formerly 3rd) - Mariabell Crois (3rd) - Thousand Oathbreaker (4th) - F. Novartis (6th) - Arianrhod (7th)|
|Enforcers||Campanella (0) - McBurn (I) - Leonhardt (II) - Golden Butterfly (III) - Luciola (VI) - Walter (VIII) - Sharon Kreuger (IX) - Bleublanc (X) - Joshua Bright (XIII) - Renne Hayworth (XV) - Shirley Orlando (XVII)|
|Stahlritter*||Duvalie (head knight) - Ines - Ennea|
|Associates||Jesters - Gilbert Stein - Cedric Reise Arnor*|
|Bases||Lakeside Laboratory - Glorious - Celestial Globe|
|Thirteen Factories||Doll Studio - Black Workshop|
|Orpheus Final Plan||Gospel Plan - Phantasmal Blaze Plan - Eternal Recurrence Plan|
|External events||Azure-Zero Project - October War - Great Twilight Plan - Operation Jormungand|
|Technology||Archaism - Pater-Mater* - Aion Type-α - Aion Type-β - Aion Type-γ - Aion Type-αII - Aion Type-βII - Aion Type-γII|
|Concepts||Sept-Terrion - Outside (Divergent Laws) - Carnage|