I'd like to see the player's attempts at Edda's salvation foiled, and her sinking deeper into darkness to the point she becomes a REAL problem. I'm thinking her despair can carry a pretty badass storyline for quite some time, while also exposing us to some serious levels of black magic and necromancy. Tam-Tara was just the tip of the iceberg imo. Edda could be a great FF villain with a great background that offers players a compelling and satisfying storyline.