This is the mark of the wolf spirit that was seald inside Korra. the wolf spirit is alwasy angery and some times trys to take contule over her. The spirit has only been able to do so twice wonce when Korras hole villige was k:lled exsept for her father who now hunts her down to k:ll her. and wonce in the hidden leaf villige in a rp but it was qwickly reseald and no lives were lost thankfuly. the mark is on her right wrest.