Hypothetical parents of Celestia and Luna.
The Alicorn queen there isn't actually mine; that's Queen Majesty, who was a unicorn in Gen 1. She wasn't in the animated show of the time, but she DID have an important role in the UK comics from the same time. Thought it might be a nice little throwback. I don't think she was the first alicorn to ever exist, but she IS the first one mentioned in all of its written history.
Her king was a unicorn, Night Spirit. A quiet fellow, shy and modest, he always wondered what it was she saw in someone so ordinary, in comparison. Sadly, he was the first in their little family to pass, and he never did quite understand just how loved he was by the ladies in his life or how good he was for the kingdom of Equestria.