__NOWYSIWYG__ I believe that the dark spirits didn't come about purely because of an imbalance: they did not in Avatar Wan's time, only Vaatu's energies could change them. Since Vaatu was locked away, there is only one possibility: Unalaq. To say this with certainty, however, requires more knowledge of how his abilities work, but I have a theory. All beings which are purely spirit have light and dark energy inside them, as Unalaq stated (why am I listening to him?). We have now seen two different sides to Unalaq's spiritual waterbending: using light energy to balance a dark spirit, and using dark energy to destroy a human spirit. Korra has only used the former, though she used it in a twofold manner during her giant-spirit-incarnation fight with Unalaq and Vaatu. I hypothesize that the way