Luna existed on the moon, far underneath Nightmare Moon's awareness, as Nightmare Moon had once been for her. The part of her still remembers love, hope, forgiveness, her sister- and the rain. She remembers the rain most of all.
Inspired by the song of the same name by Josh Groban.
I think ending a song story with a line from the song is the best way to end a song story.
I do enjoy this perspective on Luna’s banishment though, it’s very nice.