In the Eldritch-Verse, there are two types of universes. Naturally occurring, and manufactured.
How does one "make" a universe? Well, that's simple. You need to gather a TON of mana. But not just any mana, mana that is directed towards a specific mental construct. Currently the "real world" is chock full of mana. You just need enough people to focus on the same thought form.
Enter the "architects"
People who are hired by gods to create and design specific types of universes. So they write a story then farm it out to a bunch of websites. People read the 'story' and the process begins to form, what is known as, a Boltzmann Universe.
This universe's history unfolds EXACTLY as the story says it should. The problem is, there needs to be a balance between logical progress of the story, and the story being interesting enough for people to want to see it. But, if you have enough, the universe forms, usually at the point in the Story that the architect needs it to start, and BOOM. Instant universe.
The problem is, at that point, the universe not progresses naturally and logically. You might THINK the story should go a certain way, but if it is stupid for Bella to leap off a cliff, she doesn't. Now this doesn't sound TOO bad, except some stories are so poorly written that if said story becomes a Boltzmann Universe, it almost instantly falls apart. Manufactured universes are very fragile and must be carefully maintained.
Sometimes Fan fiction creeps into the design process and you get strange artifacts. Every guard in a prison named after the characters of Happy Days, for example. And sometimes, if you create a group in your Boltzmann Universe to be very advanced, they sometimes figure out they were just created five minutes ago, and are NOT thousands of years old.
Enter the Elves of Boltzmann Universe: Avalon
Unfortunately the Universe in question was a rush job. It was slapped together to act as a 'trench-line' against an invasion of demons. Yes, they held off the first invasion, but then the demons pulled back to regroup and plan a new assault. This gave the Elves time to do some checking and figure out at the end of the war, "Holy Fuck Were only three years old!" Furthermore, with some astral projecting, they managed to figure out where the original book was posted, read it, figured out they were completely fucked if they remained where they were, and, in mass, as an entire race, packed up and LEFT.
And so people for the past two hundred years have been wondering what the fuck happened to the elves. The Answer? TRYING TO KEEP THE UNIVERSE FROM UNRAVELING BECAUSE THE "HACK WRITER/UNIVERSE ARCHITECT" CUT TOO MANY CORNERS TO PUBLISH ON TIME.
That... is my elves.