Artist Desc:
 
Celestia and Luna knew they will live forever. They are going to meet, know, befriend and fell in love with ponies, who are not going to stay by their side forever. They promised one other, they should keep a certain level of emotional distant from others, for their own sake. Among that, having foals of their own, fearing the pain of seeing their own foals grow and die before them.  
So Celestia was shocked to see Luna holding a foal in her arms.
 
It was early morning when she was called to her sister’s room by Kibitz and Raven. They said it may be urgent. Celestia was confused, she was sure Luna didn’t return from the bat ponies yet. She was wrong, and she didn’t return alone.
 
Luna told her what happened, and before Celestia even could bring it up, she mentioned the promise. Even after so long she still remembered. She apologized for breaking it, but for Celestia the promise wasn’t important, she doesn’t want her sister to get hurt.
 
So she sat down and told her; she will help and support her no matter what. But also told her:
 
“I just don’t want you to regret it.”
 
Luna assured her she will not. And this is a promise she really keeps.
 

 
Additional notes:
 
1.Unknown to Luna for a while, Celestia broke their promise many times during the time she was banished. One thing she kept to is not having a foal (at least not yet). This happened pretty much because Celestia was lonely. The two sisters relied on each other for company. Also, I want to play around with the idea of Celestia being somewhat a hypocrite. Or rather, with idea of Celestia’s imperfections and, because of her being the ruler, her struggling with them.
 
2. On the note having foals, in my AU their immortality works differently from how probably the show viewed it. They weren’t born immortal so their biological children would be mortal.
 

 
I finally returned to this part of my AU/next gen. I wanted to get to it sooner, but well, I procrastinated a lot.^^’’’’’
 
I tried to make this story short, cos writing these always take a long time. But I hope the gist of it comes through.