Since Brad did his background, I figure I'll bring up the tentative one I have in mind.
The Fae are not from the world of Elemental. In their world they were a great and powerful world empire with great mastery over the magic of their world. They lived in great peace and harmony with their world's nature and did not seek after power...
until the Titans came. The Titans simply saw their world as a thing to be plundered. They wreaked great destruction upon their world and setup portals which channeled the magical energy of the Fae to another world that they had made into their dwelling. The world of Elemental. The Fae were helpless and could do nothing about the Titans but fate intervened. The Titans suddenly disappeared. This gave the Fae a chance. Their world was still being stripped of its power, but with the Titans gone the Fae could survive and eventually learn to do something about it.
A few great and powerful Channelers of the Fae have opened up the portals connecting from their world to Elemental and gone through. Some will seek to make this new world a home, some will seek to reverse what the Titans started. Some will work together, some will fight.
The Fae were all novice life shapers before the Titans came. After they came they first used these abilities to change and adapt their own bodies to what the Titans were doing to it to survive. The Fae were once all of one kind, but now they are many as they've sought many different ways of survival both in the old world and new. Additionally, in this new world they may find animals who are victims of the indigenous Men who are willing to have the Fae change their bodies to in order to be able to stand as equals and fight back against Men.
There is a downside to being strangers in a strange world. Things found on this world that are not found on their own are toxic to them, Iron and Silver are super rare elements on the Fae homeworld. But in Elemental they can be found in an abundance to be shaped into weapons that are Anathema to all Fae.
Will you join them? Make them your allies? or seek to defeat them?