The following has been put together from various talks with Elves and other Fey, including Shadar-Kai, mostly while walking between places.
In the beginning, there was the world. The great dragon Io had created the world, and had placed all life upon it. He created The Fey, and He created Shadow, and between The Fey and Shadow He created The Solid. Out of the Fey, He drew a subordinate. For balance, he also drew a subordinate from Shadow, for Io believes most strongly in balance.
Sadly, the Dragon that was created from Shadow did not like the Dragon that was created from Fey, and always, and in all things, tried to destroy him. The Dragon from The Fey was passive, however, and never retaliated. Io, seeing that this was not balance, Banished the Dragon from The Fey into The Fey, and the Dragon from Shadow, he banished into Shadow. Knowing that Shadow would always try to destroy The Fey, Io Split them from The Solid and from each other, so that they could no longer interfere.
Thus was the world made the way we know it.