For reference:

The Avatar realm has animals like polar bear dogs (featured in this story) that are basically two animals in one.
Benders are humans that can use one element, the Avatar being the exception to this rule.
Dagon (the polar bear dog) is a male name from the Avatar realm.

There's barely any mention of them bending, but I might post up a sequel chapter for that. I just liked the idea of having Wonwoo as a firebender.