That cold night, a distraught filly wandered around the castle halls. She kept trotting until she reached two massive wood doors. The creaking of wood could be heard through out the great hall. A white alicorn with a pink mane was busy reading papers and letters. The young mare stepped into the room. " Tia?" The young alicorn said to the older one. " yes Luna?" Celestia said, not bothering to look up from the papers. " I can't sleep. The moon is too bright." Luna said, looking down fearfully. Celestia looked up from her work and smiled at her young sister. " tonight I'm going to show you trick with that." And with that, she got up and guided her sister through the halls, and to one of the towers. They then stepped onto a marble balcony overlooking all of equestria. " look at the moon Luna. Concentrate your magic on making it dimmer." Celestia told her sister. " but I can't do that! I'm only a filly and I don't know that advanced magic." Luna protested. " you don't have to be older to do this simple magic." Celestia reassured. Luna sighed and pointed her horn at the moon. As she focused her magic on it the light of the crescent moon was diminishing. After it got darker, Luna lost all concentration on the moon and let out a happy squeal. Celestia beamed at her sister. Her expression changed to awe though when a crescent moon surrounded by dark clouds appeared on her flank. " Luna! Your cutie mark is there!" Celestia said, still in awe. Luna looked back and saw the mark. Then after letting out another squeal, she promptly embraced her sister tightly. " I love you Tia." Luna said still hugging her sister. Suddenly the dark blue mare looked up, with strictness in her eyes. " promise me we will always be together." She said. Celestia didn't take that long to respond. " I promise."