Far to the north, amidst thick mist and icy waters, lies a magic realm named Tír na nÓg. It is the birthplace of all beauty in the world. Brave Tuata warriors live and feast there, along with leprechauns and fairies and all sorts of magical creatures.
But once upon a time, a tragedy occurred. A fairy tribe called the Sanzhani travelled to Tír na nÓg and bade its king, Manannán, to let them settle there. The king had lived on the Island for so long that he had forgotten what evil was, so he agreed. Soon the Sanzhani met Áine, Manannán's daughter, a girl with teeth so pearly white and a smile so beautiful that all Tuata loved her dearly. One fateful night, the Sanzani stole her smile. When Áine woke up with her face covered in blood, she lost her reason and jumped off a cliff into the icy waves.
For this heinous crime, Manannan killed half the Sanzhani. The other half escaped. Pursued by the Tuata, they fled to the other side of the world. Some say they are still around, hiding in burrows, hollows, and under mushroom caps. They may let you see them, but only if they are about to steal your smile too.