Bayle... Vile Bayle!

To begin with, I feel like there's a lot to be said for cosmic motifs regarding the Outer Gods and similar beings.

The Greater Will is likened to a "lightless abyss/dark" in the Gravitational Missile and the High Priest Hat's item descriptions, and together with the fact that Ymir says that "we are all children of the Greater Will", and Hyetta mentioning that the Greater Will "made a mistake" in the same dialogue that she mentions the One Great was shattered and fractured, brings me to believe that the Greater Will is both the universe itself (a great lightless abyss, filled with very separate bits of matter) and the equivalent of the Big Bang (which is theorized to have been a very dense point of matter that exploded outward, and probably was the birth of our universe).

As for the Outer Gods (confirmed or not), the possibility of the Blood Star (explicitly a star) also being the Formless Mother, and the simple fact one of them are the Moons, lead me to believe most Outer Gods are (kind of sapient) stars or other celestial bodies.

The exception is the Frenzied Flame, which, unlike others, I don't believe to represent entropy. Entropy is the process in which energy is "lost", and it's entirely natural and slow. It's believed the heat death of the universe will come through entropy; a very slow, and ultimately cold, process. Rather, the Frenzied Flame seems to want everything to go out in a final blaze of glory, melting all back into one being/object. That reminds me of the (now defunct) theory of the Big Crunch, where the universe's growth was gonna reverse itself, and eventually go back to that very dense point of matter.

The Night from Nightreign, while very ambiguous on its exact nature, I feel is very similar to a black hole. It consumes eternally until nothing is left: not memories, not people, not the world itself. Much like a black hole attracts and "devours" everything past its event horizon to (probably) lay forever crushed on its surface or under it. The very concept of the "event horizon" reminds of the ring of rain in Nightreign's gameplay: it closes and closes on itself, preventing you from leaving its limits (unless you want to brave damaging rain, of course).

To move onto other matters, it's impressive to me how Outer Gods and beings of similar power affect their chosen.

While Marika ascended without the Greater Will (thanks Metyr), it likely eventually chose her anyways, since she's in possession of the Elden Ring aka the Elden Beast, its envoy. And, while we don't know if the Greater Will actually is about Order, since that could just be Marika's propaganda, if we assume it is, then Marika was very much about following a specific order of things, without allowing changes or deviances (see: almost every subjugated or genocided species/races in Elden Ring). Goldmask even seeks to emulate this, not wanting Gods to be able to change the Elden Ring aka the natural order of the world.

While the God-Devouring Serpent isn't an Outer God, it's still a greatly powerful being, and once Rykard was devoured by it, he took over and ended up being the exact same as the Serpent: an endlessly hungering being that doesn't care for much else, just more ambitious in its scope.

Malenia hates the Scarlet Rot, even when becoming its Goddess, yet her very body and mind have been ravaged by it, almost as if its punishing her for rejecting it. Supporting this is that Romina, while clearly mutated, isn't rotted per se, and even seems content with her situation; which makes sense, as she seemingly weaved the Rot from an earlier state into what we find in the present.

Mohg is difficult to gauge because he was charmed by Miquella, but from what we see, the whole "blood cult" thing was his idea, and the Formless Mother explicitly craves wounds and is all about blood.

The Tarnished and Midra, after becoming Lords of Frenzied Flame, seem overjoyed at the destruction going on around them; especially the Tarnished, who has just completed the Frenzied Flame's entire purpose by the time they revel in the burning Erdtree.

Finally, while the Night is once again ambiguous in its lore, there is a strong argument to be made about it being related to loss (no, not the meme). When you are afflicted by the Night, you lose memories, you lose your purpose, you can lose your life, even. And Heolstor, who has been at the center of the storm for likely many years, has seemingly lost everything too. Note how in the first phase, he starts out wandering aimlessly, dragging his sword, and his attacks, while hitting hard, are overall simple sword combos. Only when he hits certain HP thresholds does he gain better attacks, but, aside from certain added effects, the wisp attack and the two nuke attacks, they're still relatively simple sword combos. It's almost as if Heolstor lost his fighting skills outside of the Night's power. Not to mention that he has that gaping hole in his armor, which shows nothing but the Nightlord's Rune and darkness, as if he has even lost his own body. He's literally got nothing left but the armor, the swords, and the Rune that links him to the Night.