They Hide Among Us
Even in the cosmopolitan world of Erathia beings who can become anyone at any time are hard to trust. No one knows where they came from or how long they've been around, not even the changelings themselves. Pockets of shapechangers live throughout the world, most quietly building lives for themselves and their families. A few work as spies and assassins, reinforcing the reputation of untrustworthiness that most changelings try to dispel.
The Blood of Changelings
Changelings can breed with any of the other mortal races, but their changeling nature only passes on if the other parent is a changeling or has some amount of changeling blood in them. In areas where they are discriminated against or killed when discovered, many changelings seek out single-skin partners so that their "curse" isn't passed down to their children.