User blog comment:EmpyreanSmoke/Supernatural Q&A/@comment-79.115.74.119-20150730130545/@comment-24834479-20150805213306

The writers originally intended for the Leviathan to be older and stronger than the archangels, but now that we are writing the history of the darkness, we might dwell more on the story of the Leviathan. Eve was thought of as either a powerful leviathan, or half leviathan. Since the Leviathan are still currently written as above all the angels, Eve seems to be the higher of the three.