During the Great War, the Dark Realm proved superior. The world is now eclipsed within a dark era dictated by Dark Overlords and their Dark Knights. The Dark Knight Terra has fallen in love with the one person he could never have; a light his dark hands could never truly possess. How could she love a Dark Knight? How could Aqua care for one of the knights she vowed to hate forever?

Aqua had always been quiet and contemplative. She longed for the land, the Keyblade wielder, and an immortal heart. Aqua could gain all of those things, but only if Terra loved her more than anything and vowed to be true to her forever. She cut out her tongue and relented her fins to be with him, but would it be enough? [Hans Christian Anderson's The Little Mermaid AU]