There is no race of half elves in this world. Humanity is enslaved by the dragonborn, and the elves are destroyed, or in hiding. Among the dragonborn, there is an ancient and obscure prophecy about a half elf and the end of their empire. As such, human elf hybrids are considered to be abominations. There is no greater insult in the dragonborn language than to call another half-elf or gra-thark in their tongue.
Now, the prophecy is an obscure and mostly forgotten legend among the dragonborn. Still, there are some who continue to watch for the coming of the gra-thark.