Aether

Aether is a cosmic substance that is best described as "undiluted soul stuff". It is a complex substance made up of multiple components, which through natural processes separate on their own. Part of reality is also created from aether, and it's an important component dictating the structure of timelines.

Mechanics
Aether components are able to form different forms of consciousness and life, also known as soulforms. Although non aetheric life can form, it's typically only under artificial circumstances as other particles have difficultly properly replicating it without the addition of aether. There are two known components of aether, which are axiom and soul. There are the presence of other types of substances in aether that have different effects and properties, but they don't naturally influence life in the Prime Chronoverse due to the multiverse's conditions. In some cases, aether has been exhibited having a mind of its own, but to what level isn't clear.

It's an extremely hazardous substance, due to possessing a massive danger to all sentient life and reality itself. It also lingers behind quite easily, making anything exposed to it also dangerous. It can potentially mess with soulforms severely, warping personalities and causing other issues with those exposed. It can also easily tear itself through matter, often warping it as it does so. Anything that aether touches is at risk of being horribly disfigured and otherwise maimed. Because of this hazard, reapers have made it part of their law to contain aether and to prevent other entities from getting their hands on it. They protectively watch over natural aether veins in megaspace. While it is very rare, aether can also sometimes flow into multiverses through links to the aether pool, which they work diligently to remove and, in the case of timelines, to undo. They have some sort of mechanism to detect this and to stop it from flowing out before it happens. Overall the amount of incidents where they didn't prevent aether from getting into multiverses is extremely small.

Study of Aether
While unrefined aether is very interesting as a topic for scientific study, it's also really hard to obtain and contain. Not only do reapers regulate it to some magnitude, but the previously outlined hazards also make it very hard to store safely. Even reality warping resistant objects can't properly contain it.

A common method to help store it is to add aether to one of its components. This is done for storage purposes, as it effectively dilutes the substance to allow more safe storage. In this state, it's much safer (though not harmless) as well, meaning if something goes wrong the situation is much easier to manage and clean up without accidentally destroying the fabric of reality permanently. While separation for practical study isn't exactly easy, the benefits of this method outweigh the inconvenience of storage, as there are several methods depending on the component to separate the two.

There have been multiple attempts to utilize aether throughout the multiverse. However, the exact inner workings of the substance have still remained unknown - not to mention obtaining it in the first place is as difficult as it is dangerous. What is known is that souls and soul alternatives react extremely strangely to aether, with unpredictable effects on them that are typically detrimental. Attempts have been made to utilize Aether for more positive effects, but as far as anyone is aware, these attempts have failed horribly.

Aether Pool
Aether is known to be stored in a separate realm called The Aether Pool. There are no known successful attempts to directly enter the realm, though there are obscure ways to tap into the realm enough to obtain a small amount of aether. Attempting to find a way into the realm has proven extremely difficult, not to mention dangerous. This is mostly due to the hazard aether energy possess, never mind the actual difficulty in accessing the realm itself.

The Aether Pool is known to drain into multiple separate isolated yet still connected pools in smaller realms. These are mostly unknown, with purposes and properties that have not yet been uncovered in this sector of the multiverse. One of these pool types consist of the axiom pool. There have been attempts to tap into the other unknown pool types, but no known attempts have succeeded.

When any aether component is expended, it gets absorbed back into the aether pool.

Aether Based Species
There are two known species of aether based entities in the multiverse, and they both serve as important components in the cosmic processes of the multiverse.

Weavers are non-sentient entities that resemble spiders. They naturally create and maintain timelines. They are often referred to as the multiverse's mechanics, due to the fact they maintain it and ensure it functions properly. Some of the jobs Weavers do include stabilizing unstable time loops and repairing dimensional damage. In general, Weavers show up if the multiverse is on the brink of falling apart and ceasing function all together, or otherwise falling into a state of instability.

Reapers, meanwhile, are sentient. Reapers destroy aspects of the multiverse that can't otherwise be repaired. They are also responsible in dealing with situations that have to do with souls and other similar entities. Their sentience is required, as the situations they are involved in are often more complex than a broken cog in the machine. Reapers are much fewer in number than the Weavers, with only a dozen or so of them in existence.

Reapers and Weavers are often seen as counterparts in the megaverse, as what they do can be considered as an opposite to the other. Weavers create and deal with simple situations with a clear state of distinction. Reapers destroy and deal with complex situations that lack a simple black and white distinction. Of course, this is an extreme simplification as Weavers and Reapers are capable of destruction and creation respectively, but this duality is the basis of many religions.