Picture the land before the lords, giants, and humans came into existence. Grey trees. Grey, eternal dragons. And a grey landscape. Nothing changed. Nothing died. Nothing lived. It was a pure state of perfection. But not even that. Because you cannot have perfection without it's counterpart. This land, this place, was simply, there. And then, like a big bang, there was Light. Death. Hot, Cold. Imperfection. And this simple realm was shattered, forever changed. And from the ashes of arch trees the first descendants of everything built their kingdom, from the ground up, to the worlds beyond. Ash Lake, and the place that the Arch trees exist in, is ground zero, a metaphor for the universe before there was the universe. And from this, the remaining arch trees gave life to existence.
Time is fractured in the world. Heroes, people, and places, seem to exist in disjointed paths. Ancient people who have long died can cross the gaps between worlds, time and space. Other, living people, can invade from their own world through time and space. But why is this, I wonder? Why is time so fractured? Why are there so many other worlds? Because every arch tree leads to another world, another dimension beyond, high up above. And what happened to all these worlds? They met imperfection. Imbalance. Opposites. And what did the lords do when they waged war? They destroyed the eternal dragons homes, the great arch trees. When the lords rose up, without understanding, without meaning too, they fractured reality. Destroyed the clockwork mechanism of existence, by fracturing ground zero, by destroying arch trees, they destroyed worlds. Parallel existences snuffed out and forever lost, irreversibly damaging time and space to the point where what was left had little to no barriers, and no order and organization. And now that imperfection exists, it slowly eats away at the foundation of all realities, in the form of the abyss. And it will continue to do so, until the last light of existence goes out.
So, consider each tree here to be connected to another world. There's a massive tree at Firelink Shrine that must go somewhere, and even when you go down into Lost Izalith there're still huge tree roots. This might would be a way to explain how you're able to summon phantoms from other worlds to yours and possibly how NPCs from other lands are able to travel so quickly to Lordran and directly to Firelink. So, maybe instead of the crow transporting people about, there's some kind of spell or ritual that allows travel between worlds or trees across great distances. So, Ash Lake is like a hub, containing a gigantic root system, with portals dotted around along being the trees.
