Luna has returned from her banishment to the moon, purified and reborn. She should be happy, but she feels lost. Who is she? She is not the Nightmare, but not yet the Princess of the Night that once she was.
Luna was raised in the shadow that Celestia cast. That was ok, she really didn't mind at first. Slowly, over the years the light got brighter and the shadow longer. Until, it all became too much.