Ok. So with some basic terminology established, lets take a look at how I see the omniverse being structured, if such a concept has any meaning at all.

I have to admit to some bias here. My reality, as fucked up as it is, is consensual. That doesn't men everyone consented to it (because they definitely didn't) but that the basic nature of reality is determined by the prevailing beliefs of its sapient inhabitants, whether conscious or unconscious. The more intelligent they are, the more effect they have, simply because they have a clearer view of the reality they are describing, and thus creating. All creatures have some effect, however. They just get railroaded by the sapient and/or more intelligent species, especially once those creatures have an outsized footprint on reality via numbers and/or dominance. If insects were more sapient we'd be in trouble, especially if they all saw the world the same way. As it is, human and near human minds determine most of reality. This is partially because many of the near human minds that help create the Consensus are themselves products of the consensus and biased toward the mindsets of their creators.

That being the case, I find that many, if not all, realities (universes, multiverses, multiversal clusters, et al) are beholden to a set of natural laws they have in common as a result of their basis in the consensus. (Keep in mind other realities might not be consensual at all, or may actually have entirely different creatures forming such a consensus, and so have different laws... but the more different they are the further away they are, metaphysically, so one is rarely exposed to them. When they are, things get weird.)

Among these laws, fairly often, whether the world is fantastic or 'realistic', magical or scientific, it has things like gravity, (even if they don't call it that), cause and effect, some expression of linear time progression, most basic kinetic properties, etc. They all also seem, due to the way the human mind works, to have, to some extent, what some fiction authors call narrative causality. IE, some things happen the way they do because of the weight of the story, the stereotypes of stories, the conventions. This honestly seems inevitable, at least for consensual realities, because that's how our mind works. Everything is part of a story or narrative, and some outcomes seem vastly more likely than others based on how compelling a narrative structure and its themes are. So if you, sitting in a world you are convinced is objective (it isn't) and rational (it isn't) are scoffing at this like it's a dumb fourth wall break, really think about it for a while. I'll wait.

All that being established, here's how it works.

My reality is sometimes called the World of Darkness. Some folks think that's a reference to how bad, corript, and evil everything here is, and that's part of it , but it's also a Gnostic reference. Well. A reference, specifically to the dualistic Manichean worldview, wherein the world of light was invaded by the materialistic world of darkness, and that the world we live in is the dark one, made by the forces of evil, and one must transcend it to reach good. This is pretty damn bleak, and may or may not be accurate. We'll get to that. But. My World of Darkness, or WoD for short, is hardly the only one. There are many, all with basic similarities. All have mages mostly like ours, vampires, werewolves, mummies, demons, all that. They vary in a number of ways in the specifics, like history, nature of individual groups, and more. But the WoDs can easily be considered a multiversal cluster. Each of the WoDs, basically, is a multiverse, of course. In mine, you have the physical world, the Underworld, the spirit world or Shadow (werewolves call it, variously, the Umbra or the Hisil, and some mages follow suit), the Supernal Realms that the Atlantean Orders believe in so strongly, and many more. All technically part of our reality, thus our multiverse. Each of the WoDs has their own version of that, with more or less variety. And worlds that are similar , but not strictly WoDs, like worlds where all wizards are bound by the White Council and deal with the White, Black, Red, and Jade Courts of vampires, just for instance, are part of a larger multiversal megacluster.

As another example, from current pop culture (don't get me wrong, I'm sure these places exist), take the Marvel Cinematic Universe. Just like the comics it came from, it starts with one universe, then starts to explore its multiversal cosmology with alternate timelines, other dimensions, etc. But the MCU is actually a fully separate multiverse from the Marvel Comics multiverse, while together they form a cluster...and there's areguably a megacluster of 'superhero' universes that includes the various DC multiverses, and all the rest.

As a third example, a multiverse where the children of ancient gods walk the earth in modern day and fight ancient mythological terrors from Asgard to various Underworlds to Heliopolis might refer to what some of us call the Scion multiverse, or to a world like the (fictional?) Riordanverse...or even that same wizard reality with the color coded vampire courts, because they have that stuff too. Universes and multiverses can be part of multiple different clusters, where their likenesses intersect with other realities.

All of these examples, by the way, are worlds I've seen, except the super hero ones, they also seem to be in some measure consensual (but that might just be because my framework is) and they all seem subject to narrative causality. Some even have high minded words for the process, like Fate, Destiny, or Kismet...all ilustrating that the story has a huge effect on the reality. Go back and check out my piece on prophecy for another perspective on that.

https://www.ofgodsandgamemasters.com/blog/time-and-prophecy

Anyway. Imagine each and every one of these universes as a spherical node. Each node is tied by paths to a number of closely related universes arranged also in a roughly spherical pattern (mostly for conceptual purposes, we have no idea if there is any 'spatial' relation or is such a thing is even real outside of individual universes). Thin, utterly flexible line connect these spheres to other spheres, with the ones that are most similar being 'closer'. But all of the spheres move and shift in relation to each other all the time, possibly based on changes to their individual consensus, which brings them occasionally into 'closer' proximity, allowing easier access, or pushing them farther away, making transit more difficult. Like molecules shifting due to Brownian motion. Different realities also seem to be able to share the same 'space' with each other, making them coterminous across differing dimensions, and allowing very easy transit during these 'conjunctions of the spheres'. Sometimes even accidental transit. Things just sort of move from one reality to another without any apparent rhyme or reason. I say apparent, because if narrative causality is a thing like I think there is, there's a reason we just don't get.

Now here's the HPL cosmic horror bit. Many of these realities have concepts of places between, of unreal places, of primordial Khaos before creation. My world calls this place the Abyss, sometimes. Sort of. A place that isn't a place. A place with no time, because that's a thing of reality, and this place, this stuff, isn't real. Although it definitely seems to be...present. Despite not being real. How the hell do we define real anyway?

Anyway. In between the rotating and gyrating dancing spheres of realities and universes and multiverses and clusters, there's something else. It was there, in almost all conceptions of reality, before reality. Before the 'Creation' of the 'World', however that came to be. And it’s still there. Always was, always will be. Indefinite, infinitely infinite, eternal, timeless, shapeless. Often, but not always, immaterial, but that depends strongly upon your frame of reference. And, well. Things exist there. Live there, maybe? And some of them are really cross that these little gossamer bubbles of 'reality' are floating around in their primordial unreal soup of Khaos. Some are just curious. Some we cannot possibly concive of what they are thinking, if they think. That's..that's probably actually all of them, regardless of what we think we know. And given that there are literally no limts to Khaos, no time, no space, no end, no beginning, there are no limits to their numbers. The idea of numbers is in itself meaningless to them. There might be a single, I don't know, Yog Sothoh, for instance. Or 50 million. Or both. And infinite variations, and totally different 'Elder gods' that may still, sometimes, be the same ones, because the only rule is there are no rules. But one thing is certain, and most realities agree on it: the Outside is fucking dangerous to everyone and everything everywhere and everywhen, and should not be fucked with. The earliest creator deities of each reality, if they exist at all (which they do, even if only retroactively, because causality isn't directly linked to temporal flow, I know I have another article on this somewhere) have to have come from the Khaos Outside because that's the only 'place' uncreated things come from.

“In the beginning, (GOD) said, let there be light.” And a limitless number of undefinable entities were very cross at the sudden noise and light. I mean, look at the way Apsu and Tiamat reacted.

And thus a reality was created. That was that reality's beginning. This kept/keeps/will happen across the timeless Void, and some of the denizens thereof really don't like it.