The story has been canceled in 18.12.2020
Cancelation reason here

Nightmare Moon has long wanted a child. She dreamt of a foal that would love her and call her mama, and she would take care of him and love him. But no one was able to give her that because all the inhabitants of Equestria were afraid of her. She was thinking about adoption, but it was more than impossible. One night, when she was sitting by the riverside just to think, she heard a loud cry for help and something, actually, someone trying to stay on the river, which mercilessly dragged a small, frightened, and cold drowning foal. Nightmare Moon saved him from death. The little one lost consciousness and was almost drowned. She took him to a hospital in Ponyville and adopted him a few days later. But she didn't know that her child was not an ordinary foal until she noticed that he had mysterious abilities, which are unusual but also extremely anxious.