You walk the streets of Sigil on a particularly oppressive Day. The smog is thick enough to make even veteran cagers choke. It even makes some places in the lower planes seem pleasant compared to this foul day. Everyone should try to stay in their kips, but the streets are as crowded as usual anyway. Only the number of curses escaping lips, twisting through the fog and worming their way into your ears, is higher than usual.
The mist is so thick, that anything more than ten steps in front of your vision is completely obscured and anything further away than a hand's width or so is only shapes and shades. Sluggishly clouds of the heavy mist waver and roll over you. Carefully you watch your step to avoid missing your way.
Taking wrong turns in a great city was always problematic, but it was at least doubly dangerous in Sigil. Every archway could be a portal, or you could run into the arms of a fiend lurking behind the next corner. You hear a voice from a nearby alley. A voice that seems to be calling out to you, but the mist warps the echoes in ways, that make it impossible to determine.
The voice calls again. The mist seems to part somewhat into the direction of its origin. A shady figure is there, only a silhouette, surrounded by ghostly light. What quirk of Sigil's odd architecture makes this possible, or if it is the strange appearance result of magic use is impossible to discern. Naturally peery, you wonder: "Fiend, friend or barmy", as you slowly advance.
Even as you draw nearer, the figure remains shapeless and cloaked by the mist and something else. You don't have the slightest idea, what it might be. "Listen cutter", the voice says. This time you are sure it originates from the figure. Looking into its direction, you wonder if you are making a mistake. "I have a piece of chant, I want to share -with you."
The part of the shape that should be the head seems to move into several directions. You decide to stay and listen, even though the chant you will hear might possibly be dangerous. Curiosity overwhelming caution, you step closer to the figure, recognise a remotely humanoid shape. The shadowy effect seems to be the a result of the cloak the being is wearing, as the face beneath the cowl stays in position, as it is supposed to.
The face alone appears human at a first glance, but something strikes you as odd, something you cannot define. The complexion is wrong and the eyes are constantly darting around in the manner of a paranoid. Haunted and strange, mist swirls in front of the face like the tendrils of a creature, always concealing part of it. Each time you look it changes a little. Every change is maddeningly beneath the level of conscious perception. You know it changes, but the changes are impossible to see. The figure starts to speak, its voice unexpectedly pleasant on your ears, but without any clear identification of gender.
"You have decided to bear with me, so I will share the chant with another cutter. Be warned, that this particular dark might be dangerous, so that you may still leave. See, it is about her serenity, you know, the Lady of Pain. I will shed some light on the her mystery. You don't believe me? Well, take some of your precious time to listen to what I have to say.
"The cage is like an anthill. The dabus are the most obvious of the ants, the worker drones, keeping everything going. On the way they take resources from all over the city and from below, where their vast tunnels honeycomb all of Sigil. You think the hive is a confusing mess? If you think so, you have not seen the confusing labyrinth below, that most call the warrens.
"Sigil being aeons old, some think that the warrens are in truth the remains of previous incarnations of the city on which the next layer had been built on which the next layer had been built, and so on. Others say, that the tunnels are as old as the cage itself. As far as I am concerned at least for some of them it is true.
"In the center of the tunnel system -- don't ask, how there can be something like a centre of a ring, a lot of things in the multiverse don't seem to make sense from our mortal perspective. -- is the home of three beings, running the whole show. One is responsible for the drones (dabus), the second co-ordinates the warriors, who do the work we think the Lady of Pain does.
"What we see, hopefully from a save distance, is only an illusion to hide the work of these warriors. Their true appearance is only speculation, since even modrons see only the Lady and nothing else, and if they can't see through an illusion, who can? It also shows that we are talking about incredibly powerful beings here.
"Obviously these critters are not nice, if you have ever seen, what happens when the Lady of Pain appears, you know, what I am talking about. It is believed that they either have very formidable and sharp natural weapons, or they use weapons made from a material thought lost to time. It also seems, that they only react, when something is badly out of sync.
"It is also said, that all those people randomly disappearing aren't due to accidentally opening portals, but the result of assassinations skilfully carried out by these warriors. This leaves only the third member of trio, the breeding queen, who lays the eggs.
"These eggs are tended to by specialised drones until they hatch. At this point it is obvious, which type of creature the young hatchling will become. They grow up among their breed and learn their duty, until they are fully grown and ready to fulfil their duty within the city, maybe even beyond. This leaves the rule of threes unsatisfied, right?
"We have warriors, drones, and ...? My guess is, that the third are spies, but that's only me. Honestly I do not know the answer. I have also heard, that people say the third type are the cranium rats. Tiny, small, always part of the city, they are usually ignored. The pack mentalities of cranium rats seem to indicate, that they are hive-minded in some way. They might be the spies of the three rulers.
"It can also be said, that all of them are hive-minded and they know everything seen and otherwise picked up by the dabus. The third theory is, that the three are a living incarnation of Sigil's spirit, because the city itself is a living being in a sense we cannot comprehend. It might also explain a number of other things, but I still have to research this dark.
For a few heartbeats the shadow covering the cowled face seems to become even deeper than it already is, cloaking it even more. The figure seems to start saying something, but doesn't. Obvious is only a short pause, before the speech continues:
"The three are living beings, and everything that naturally lives will die someday. Everyone knows that and the Doomguard even make a philosophy from it. Mortal live is not called that, because it is made to last forever. Again there are three theories, how the three reproduce, since they are all believed to be female, and standard breeding procedures don't work.
"First: They might take control of some poor sod's mind and slowly transform him, her or it physically and psychically into the creature, so that the one can take its place when the time has come. In the last moments the knowledge of the being is transferred into its successor. Naturally the victim has to hide, once the physical deformities become to obvious. Then again maybe not, considering the many odd creatures in seen in the cage.
"Second: They might breed a special symbiont, that looks for a likely successor and merges with him, her or it. Then the transformation process starts and the chosen one vanishes some time after that. Of course with Sigil being the city it is, no-one might take special notice anyway.
"Third: This is the most violent theory, postulating that a parasite is created, that will be injected into some sod's body and breed inside. Then it either usurps control of the host or it eats the host from inside to feed and leave once the host is dead. I think someone messed them up with another creature here, but then again they might be right.
"That's it for now. Maybe we will meet again some day."
While you try to digest what you have just heard, you are distracted for a moment by a screech of something bird-like nearby. When you turn to face the figure, it is gone, leaving only empty mist behind and you cannot even hear steps. The tiefling - at least you assume it was a tiefling - disappeared as quickly as it appeared out of the fog. You quickly retrace your steps and continue your way to do, whatever has forced you to dare the streets today.
You start to wonder. Was it a trick of your mind? A trick played on your mind? Barmy talk? A frightening and potentially dangerous dark? There is no way to find out.