The Fairy Ending is an Ending in Prisoners of the Elder One. It occurs after touching the flowers in the Garden thrice.
Lilly, annoyed with Erik's misbehavior, transforms him into a fairy girl to show him the harm he's done. She immediately apologizes, and spends the rest of her life helping Lilly maintain the garden, though she doesn't forget her previous life, or her sister that is still trapped in the mansion.