Luna was the apple of her mothers eye and when she died her mother grew depressed and refused to face her other pups as she was angry that her only female pup died while she had plenty of male pups that could have died in her place. Luna was already born weaker than her littermates as she was the runt and wasn't expected to live past a few weeks as their cold environment would make breathing and moving difficult for one so young. She lived past their expectations and was suspected to grow stronger by the next month but then one morning she awoke before her littermates and mother and was determined to show she could be strong and run around like them. She left the cave and wondered into the surrounding forest where she encountered a calve and along with the calve their protective mother. She ended up dying that day and her death caused her mother to become angry towards her remaining pups, causing two of them to run away in hopes of a new life, while one stayed to try to help their mother. Moon is the only one who stayed and is determined to always remember his sister and is determined to help his mother reclaim her sanity.