A thousand years ago, Celestia was forced to banish her sister to the moon. On that day, a part of her heart was ripped out and cast away. For a thousand years, she's been forced to live with that pain. Except for one day each year. On that day, on the eve of the Summer Sun Celebration and the anniversary of her sister's banishment, she finds a way to relieve that pain. She finds comfort in the embrace of another. She finds a way to ease her pain.