Shadow is a dark Stallion which is skilled in forbidden magic, and he is in the night royal guard which protects Princess Celestia during sleep. All things considered she gets little sleep, making it an unpleasant job. Having been cheated out of the title, caption of the guard and Princess Celestia's personal guard by Shining Armor, he is given a second chance as Princess Luna comes to live at Canterlot
The story has very limited use of bad language. Has suggested scenes, but no actual sex scenes.