The last avatar
As the artist says: "You guys don't even need to ship this, okay? It is just is, and you need to just love it because everyone wants this. Everyone wants a Zuko/Katara hug in Korra." and as one of the commenters says: "We NEED a Zuko and Katara hug in Korra- they are the only memebrs of Team Avatar that are still alive!" I really believe that that has to count for something.