Calen is an elf who was bitten by a werewolf. Most elves who are bitten tend to kill themselves rather then live with the burden, but he didnt. He instead ran. He ends up living with a human blacksmith named Ivan who he finds out is also a werewolf and this is how they sort of gravitated toward each other. Werewolfism works a bit differently for elves then for humans, changing some of his feature permanently, most obviously leaving him with a tail at all times. His friends call him Gaur, usually pronounced gow-er.

More Info here