Who are Stellar Skys and Nebula Quazar (hope I spelled those right lol) very intrigued with the post about them. Are they Celestia’s children? Past students of Celestia? Luna’s children??? I am so intrigued.
They are Luna's first friends, Celestia and her find them one day in the everfree forest after a meteor shower (Celestia was about 16 years old and Luna around 12 years old, Stella and Quaz' was probably 9-10 years old for what they can tell). Long story short, they bring them back with them in their Castle in the forest and ask Starswirl if he knew where they could come from but he didn't know either and the two little filly didn't remember anything about it. So they lived with the two sisters for a while until one day they decided to leave Equestria to find more about their origin, but thereby leaving Luna without any friends (except her sister) again.
Both their magics are link to the stars except Nebula Quazar one's tend more about the "dying star" side of it. And they are twin sisters, although Quaz' play the role of the older.
I hope my explanation is clear enough, english is not my first language and I sometime have a bit of trouble when it come to explain things in such long sentence.
Just to be sure that I'm clear enough here the event in chronological order, with some more detail :
- A meteor shower occure (that night, Luna wish she can make friends with which she could admire the beauty of the night)
- Later the next day Celestia and Luna find two alicorn filly in the Everfree Forest being Nebula Quazar and Stellar Sky (they assume that, like them, they probably came from outside of Equestria and are not born here)
- They go to their mentor, Starswirl, to see if he can help them since the two filly don't know where they come from but Starswirl don't know enough about alicorn (or at least naturel one that are born like it and didn't become one, like Cadance and Twilight will in the future) and their origins to answer them.
- Since the twin have nowhere to go, they keep them in their castle and help them learning how to control theirs magics, and they become Luna's Friends (Luna being happy to play the big sister/mentor role for once)
- Later when they are adult, the two of them leave Equestria to seek answer about their origins. And Luna lost the only two friends she had managed to make at that time.
- Present day, following a letter from Celestia, they came back to Equestria to break the seal, create by the Elements, on the moon with their joint powers. And therefor freed Nightmare Moon from her prison.