I have decided to give anda all Moon Dust's back story so enjoy and comment!
Moon Dust was born on Hearths Warming Eve. Her father was a pegasus named pohon Whisper. Nopony knew who her mother was. Moon Dust was delivered onto her father's house the night she was born oleh Princess Luna.
Luna berkata she found Moon Dust in the snow oleh the kastil, castle with a note telling the princesses he was her father. Luna berkata she sensed great power from this filly. pohon Whisper asked her to name the filly because naming the filly was not his job.
Moon Dust was named Moon Snowy Dust Moon Dust for short. pohon Whisper raised Moon Dust until another filly with a pelangi mane was delivered to his house with a name and note saying she was named pelangi Wing. oleh then Moon Dust was 2.
When Moon Dust was 10 she was accepted to Celestia's School for gifted unicorns and when she turned 12 she was made Luna's apprentice.
So that is most of Moon Dust's back story