Celestia and Sombra from the “Reflections” universe were deeply in love with each other, but their romance was forced to end after the mirror to his world was shattered. They did conceive a child before they were torn apart, however. Celestia was an emotional wreck at first, wishing they could’ve raised their child together, but was able to calm down a bit and be happier about the pregnancy as time passed and she got used to the crazy hormones.
 
Celestia has tried having a few other relationships, but hasn’t been able to find someone who clicks with her as well as Sombra did (though it did lead to a strong friendship with Queen Novo). She’s currently considering dating Thorax, especially since it could lead to stronger ties with the changelings.
 
Celestia hasn’t told Aurora (or anyone else aside from Luna and the Mane 6) who her father really was, largely because only she, Starswirl, Luna, and the Mane 6 ever knew about the magic mirror and alternate universe. All Aurora really knows is her father was someone Celestia loved very much and she can’t reveal much information about him (which definitely doesn’t frustrate Aurora at all).
 
Aurora Borealis  
Female unicorn, 23 years old; the Crown Princess and future Queen of Equestria. Seems perfectly regal, dignified, poised, and well-adjusted, but hides a lot of the stress, pressure, and scrutiny she feels she’s always under. Loves the thrill of being irresponsible and reckless. Often cracks and plays hooky (much to her mother’s chagrin). Loves her mom but hates how vague and mysterious she is; Celestia just doesn’t know what it’s like to be a royal bastard with unknown origins. Secretly dreams of running away and living a normal life.
 
Small Design Notes: Changed Celestia’s color palette to make her reflect daytime and the sun a bit more. I’m not 100% satisfied with it, though, so it might change in the future - please let me know what you think! Sombra is half-chiropteran (bat-pony) in this AU; I haven’t figured out what the unicorn & terran versions of them will be called yet (since “chiropteran” refers mostly to animals having bat-like wings), so any suggestions would be appreciated! I was originally gonna make Aurora darker/grayer, but I wanted her to stand out more from her cousins.