Don't get me wrong the fic is good but they didn't originally create Midnight. She was originally created as one of the many OC's by Deviant art user Equestria Prevails, the art predates the story by several months and the artist's name is even used by Cosmonaut.

Here is the original picture that he uploaded to the sit (also the picture used as the cover art for the story). https://equestria-prevails.deviantart.com/art/The-Shadow-309824159