I was watching Korra and got to wondering why no one did an Avatar roleplay. So here's my idea in a nutshell.
After Korra died one hundred years ago, they went to look for the Avatar but couldn't find them. They did, however, find children, the descendants of the people of multiple nations, with more than one bending ability. They took these Perspectives to train them, to see which one was the Avatar, but none have been able to use all four elements. The Perspectives do the work the Avatar once did, bringing balance to the world. And so, they continue to test them, hoping to one day find the Avatar.