Anyone who claims to know the true origins of the Abyss is either delusional or lying. There is too much corruption for even demons to know.— from "Stand against Chaos," a presentation by prof. Errienbeck
The Abyss has many days across cultures and ages - Hell, the Void, Chaoshome, etc., but all recognise its destructive influence. The same phrase can refer to the dimension that demons come from, the demons themselves, and the corruption they bring.
Demons
Many strange entities come from the Abyss. Many are humanoid but marked with some sort of corruption, others are oozing piles of flesh, made from pure shadow, or something even more strange. Their motives seem nearly as devided as their appearances, with each of them aiming for their own kind of perversion or destruction of reality.
Demon Lords
There seem to be a dozen extremely powerful beings who are unable to fully leave the Abyss at all, but that force weaker demons to do their bidding. Their exact numbers or identies aren'y known, but fear of them is widespread.
Landscapes
Almost all sources of information about the Abyss are demons and thus not very reliable. Some have described lakes of fire, others bogs of decay, or just an empty void. Other locations seem wonderful and are described as palaces covered in jewels or caverns of extreme pleasure. All of these locations appear intended to manipulate the target, but there are also consistencies in how areas are described that makes it possible they are factual.
If any of the stories are to be lieved, the Abyss is vast and varied. All places are extreme versions of what might be found in the regular world. Arctic landscapes are colder, wealth is more austentatious, etc.
Theories
As noted by professor
Jebbediah Errienbeck, the origin of the Abyss isn'y known, but there are some theories that hold more water than others.
Pimeval Chaos
The so called, Primeval Chaos theory holds that the Abyss is the original universe. In this theory, the gods came into existence in its chaos and formed what is now thought of as the world by bringing order. This was an affront to the demons in control and that's why they want to see creation corrupted. There is a further split within the theory regarding if the Abyss is a much larger dimension that
Deis us a picket-dimension in, or if the Abyss was trapped inside Deis.
Those who have little or no reverence for the gods might well take a liking to Primeval Chaos theory. It carries a stronly fatalistic point of view where it seems all but inevitable that the Abyss will sooner or later devour the world. What was once just chaos will be chaos again.
Decree
Some argue that the gods wouldn't have been able to create a world if the Abyss was already around. Instead, they point to how much pain in the world seems to be the direct result of the gods' actions and reason that they likely created the Abyss themselves. In their eagerness to create, the gods also tried making the corrupt version of each thing. Only when the ones they created revolted did the gods push them into a separate dimension and try to keep it locked.
This approach assumes the gods were uncaring at best and horrifying at best. Some even argue that demons should be helped to fight the
The Fates, or at least dewserve sympathy.
Cosmic Balance
Cosmic Balance theory mostly agrees with Decree theory but differs on one important point: it argues that the demons weren't created intentionally. Or rather, it argues that creation as a process must result in more than one aspect of something being created. Making a universe must also mean creating the destruction of that universe. Giving it the ability to achieve greatness must also mean giving it the ability for damnation. The Abyss is a natural consequence, not an insidious plot.
This is a popular theory among many of those who use
Arcana. Not only do many see signs of the theory in the way arcane power use, but it's also comforting to think of that power as neutral.
Soul Rot
This theory claims that the gods would have no reason to create the Abyss and would have been able to wipe it from reality if there wasn't anything else keepng it. What the gods didn't want to lose were the peoples they had created (and eventually gave their lives for). Thus, the people must be what makes the Abyss exist. Soul Rot is the idea that corruption and moral decay amongst kith is that creates the Abyss.
Soul Rot is a very popular idea to bring up by anyone who wish to spread their dogma. There is a clear correlation between the connection wth the abyss and the amount of pain kith cause each other in an area. But it's also true, that accusations of Soul Rot spread like epidemics and often cause more suffering than was there to begin with.
