Other titles for Mammon's Emissary include: "High Priestess", "Reverend Mother", "The Watchful Mother", and "Adjudicator". These titles are mentioned in KSBD 9-111, KSBD 9-117, and KSBD 9-118.
Mammon is on very familiar terms with his Emissary and he relies upon her to fill several important roles. The High Priestess advises Mammon, gives him emotional support, and acts as his personal bodyguard. It is presumed she attends and accompanies him personally most of the time. So far the Emissary has only been referred to by her various titles and not by name. Mammon displays affection for his Emissary and speaks intimately with her - calling her "my dear".
The High Priestess practices mortification of her flesh. As a way to identify with the suffering of her god Mammon, the High Priestess has endured or inflicted multiple piercings upon her person. The Reverend Mother strictly enforces her own sexual abstinence - keeping her nether regions contained under lock and key.
When first encountered by Allison's group of Vault raiders, Number One appears as a Madonna figure dressed in robes and bearing a halo. She speaks serenely, commandingly, and with great authority and confidence.
Upon Mottom's Invasion of Mammon's Fortress of Yre,* in the resulting confrontation - The High Priestess casts aside her robes and reveals herself as ready to fight and strapped for battle.
The full extent of the High Priestess's powers are unknown. She is powerful enough to block a direct attack Mottom made against Mammon. From the key of kings granted to her, the High Priestess has manifested flaming weapons of pure energy in the shape of an "Axe of Judication" and a flaming sword.
The personal history of "Number One", aka Mammon's Emissary is unknown. It may be presumed that she was an accomplished and ferocious warrior before encountering Mammon. At some point she elected to join his following and devote herself to his care and protection. In that as yet untold story Mammon empowered this already formidable warrior - making her his avatar and granting her vast powers though a portion of his "key of kings".
"IA! The Reverend Mother! The Watchful Mother! She that sleeps not, and holds the key and the gate. Through a lake of blood she has ascended above the filth. Through a lake of blood she shall yet wade, and yet she shall not be stained. Praise her, and venerate the Count !"
- [Seeker of Thrones 9-111 ]: Commentary from Abbadon.
She first appeared in the comic as she sent the Priests of the Count into the Prison of Air, where they were mostly slaughtered. She didn't participate in that battle but appeared again on Mammon's side when he later encountered Allison. There, she chastised Allison as a "little creature. A wretch who hath mistaken strength for power."