Board Thread:General Discussion/@comment-25896389-20151007045033/@comment-6302057-20151117120034

There does not necessarily have to be a "Light One". The Dark One only exists as the Darkness was bonded to a human soul to contain and control it. "The Light" may exist as a magical entity, like the Darkness did when it was briefly freed at the end of 4x22, but the Light likely would not have been bonded to a human soul like the Darkness was as there would be no need to contain it.