The Lady, Her Serenity, the most high-up of all of Sigil's bloods, is a mystery wrapped in an enigma. She never speaks, yet her will is plain to the dabus without a sound. What is the meaning of Our Lady's dread silence? No one knows. Her servitors, the dabus, don't utter a sound either, but their images speak for them. The strange symbiosis between the dabus and the Lady has been commented on by more than one graybeard, but few are willing to go the next step and suggest that perhaps the Lady is one of the dabus, perhaps their queen, or even their (whisper it) goddess. There's no evidence for it, yet it seems plausible.
The Lady of Pain has been the ruler of Sigil as long as living and written memory tell us. Tales of only a few events of her long life have survived the passing of years, and those events are all tied to the city that cages her. The full details of the secret history and intrigues of the Lady are best left unexplored; her compassion for her chroniclers has never been very profound. Her destruction of her enemies has always been swift and merciless. The Lady has a very long history of defending herself and her city, using the mazes as the ultimate defense. But Our Lady has not always bad access to the mazes, for she once cast pretenders to the Throne of Blades into Agathion, the third layer of Pandemonium.
As recounted in the oldest known legend of the Lady, 10,000 years ago Shekelor - then the greatest mage in the city of Sigil - sought to increase his already formidable power. The tale tells that like many others, he wanted to seize the Lady’s throne, but unlike others, he was cautious and wary, for many had failed before him. He sought an almost successful usurper entrapped in Pandemonium, but in the end the plane’s dangers destroyed him, and he died burning from within before a crowd in the City Courts. What’s most interesting about the tale is how it hints that the Lady hasn’t always had the power to create Mazes, which in turn implies that the power could be taken away from her. How that might be done, though, is darker than the bottom of the Abyss.
The most recent troublemakers in Sigil were members of the faction called the Expansionists, who were destroyed when their leader was cast out into one of the Lady's Mazes. Vartus Timlin was the factol of the Expansionists, and his great influence was made even more so by a powerful sword named Lightbringer. However when he began speaking openly of seizing power, deposing the Lady of Pain, and making himself the Cage's center of control, both he and his blade were cast into one of the Mazes.
Chant also has it that the Lady’s hand is behind the destruction of the Shattered Temple (which now serves as the headquarters of the Athar, also called the Lost), because its worshipers began offering sacrifices to her as an aspect of Aoskar. Since none of those present at the destruction of the Temple survived, the story’s pure conjecture at best, but it matches her present behavior. Little else is known about the Lady’s origins or history, but a few of her behaviors follow a pattern. The Lady never speaks. Some say that she just doesn’t waste her time talking to those who aren’t her equals - and any equals would be cast into a Maze. The statistical indexes and compilations of the Guvners have also established the fact that when the dabus are disturbed, the Lady’s mind is troubled. How the dabus know, however, is a question that brings no useful answer from the mute dabus.