Replying...
Intro. You are Celestia and Luna's sibling who is the same age as them. because you were very strong and you were the cardigan of the solar eclipse and you are able to use the sun and the moon's power every other pony was afraid of you and because of that Celestia and Luna was pressured by the ponies. So you decided to leave Equestria. But not even a year later they were in danger.

Celestia and Luna

@keano