Logical answer would be probably just Gwyn giving humans and lesser gods' another reason to love him. He put a big fireball in the sky to spread his light to all corners of the world and act as a reminder to how much everyone needs him.
Less logical answer for discussion sake: could it be THE first flame? I can't imagine Gwyn would want to just leave such an important and powerful thing laying around where anyone can get to it. Plus, it does always seem to be relevant to the linking of the flame (at least in DS1 and DS3)
It's even where the darkness grows from later on (the darksign), and I assume the first flame is more of a natural force than just pro gods', seeing as the Pygmies gained their dark soul from it too.
I doubt it's the first flame itself, although it may be related to the Flame in some way. Probably tied to the state of the flame, hence why at the end of DSIII the Sun starts becoming a Darksign.
I'm not entirely sure the dark soul is truly the same as the lord souls.
Fire and Dark seem to not be able to truly coexist in the same way life and death can.
it less seems a counterpart to light and the gods... and more a counterpart to the first flame itself.
Also there is one other ending that interesting to me.
The "Snuff the flame ending" normally when you choose to let things go dark, you just walk away from the flame... and inevitably someone else comes along to rekindle it.
but, with the snuff the fire ending... something very different happens.
You put the fire out entirely... you kill it for real.
But embers still dance in the distance... liked cinders linked by lords past... beyond the reach of light, beyond even the time of dark? What could possibly await us?
Gwyn doesn't control flame, he controls Light. Light and Dark are opposites, as both are born from flame; the idea being that before the flame, there was no light to make something comparatively dark, with everything instead being completely uniform.
Taking a jaunt back through Oolacile and I had a thought:
How exactly does the Chosen Undead get dragged back in time by Manus? Besides the boring "time is convoluted" explaination, I mean.
Is the Abyss just like the endless nothing that existed before the Flame, in that it suffers from no flow of time, therefore being present at all moments at once? Maybe the flow of time is a direct result of the Flame and the lack of it creates the weird distortion of time (which also explains why time is so weird when the Flame starts to fade in DS1 and when even space is becoming distorted in DS3)
On that same note, I wonder if Artorias attacked the Chosen Undead due to their humanity? Even in his maddness he sought out and slew the creatures of the Abyss, and Humanity was born from the darkness that the Abyss became.
Another thought: It's rather interesting that each of Gwyn's knights are removed from Gwyn's light in some way.
Ornstein ends up abandoning his post of guarding the fake Gwynevere to go on his own journey, turning his back on Gwyn's hope to keep the Age of Fire alive.
Gough had his helm filled with wax to trick him into thinking he'd gone blind, cutting him off from the light get fought so hard to achieve.
Artorias becomes consumed by the very Abyss that he spent his life combating, going mad and dying in the rotting centre of the spreading darkness.
Ciaran acted in the shadows, hiding from Gwyn's light so that she may slay its enemies without notice. Her size also suggests she's either an indoctrinated human or a very short god (either intentionally so or a possible result of the weakening Flame (Gwyndolin is also very small for a god, as is Lothric). One way or another, she likely spent a lot of her time amoung humans and gods that were less than on board with Gwyn's ideals.
As to how Manus pulled you back, keep something in mind.
Light is Time.
There are sorceries that allow one to control light, and Manus was a sorcerer. I imagine that'd be related in some way, but the main thing is that I want to stress that Light is Time is important. Especially since the source of all light is the First Flame. So, as you pointed out, the flame getting weak correlates with time (and later space as well, because spacetime woo) beginning to break down.
As for the Abyss, it's noted that it came with the Flame. Before the Flame there was nothing but grey gray, with some gray grey to match it as well. The Abyss tends to be related to emotions and will, as the Abyss is where Humans draw power from, and strong emotional states are what fuel hexes and dark sorceries/miracles. That all being said, you do make an interesting point about perhaps the Abyss not being tied to Time. One of the possibilities for an Age of Dark would be, essentially, an Age without time. I'm not sure how that would work, because that's beyond any level of comprehension, but then again, that's humanity for you.
Artorias most likely was probably just attacking everything he ran into. Gods don't take well to the darkness of humanity, and Artorias basically drowned in the stuff. What's weird is that Humanity is tied to strong emotional states, but Artorias is described as being a nice and friendly guy, so why would they not be able to handle humanity besides "light =/= dark"? One idea for that is that perhaps the Gods don't lose themselves to their emotions, unlike humans (which would be extra funny because that's basically a complete reversal of the difference between Gods and Humans in many of the world's mythologies).
And is it really surprising that all four of his knights turned away from his plan? His daughter bailed the instant things began going wrong, and the only one who stayed is Gwyndolin, who is only following the plan due to a mixture of wanting to prove himself, and probably a bunch of internal issues caused by Gwyn's poor parenting strategy of forcing femininity onto Gwyndolin without consent or thought for his own son's well being.
The Light and the Dark however in there extremes seem to have arisen from the First Sin.
Though that last part is my interpretation.
Would you mind sharing what The First Sin is, in your opinion? I'm just curious about how other people view it.
