The Queen's castle has a special aura at night.
As chilled winds blow slowly through the halls, through spaces of cracked and broken stone, a soft whistle can be heard. It was dark, only few candles lit and the sconces flickering and frequently going out. Ponies shuffle through: workers and maids, guards, even civilians who have come to the castle for a few hours with requests or complaints. Tapestries depicting the reign of Nightmare Moon, including the defeat of Celestia the Wicked, Nightmare Moon setting the moon in the dead center of the black sky, and an especially large one of ponies cowering in fear as Nightmare Moon looks on with blood red eyes.
Of course, it was always night. Rarity liked it this way. Her mother had told her of what life was like with the sun: it burning her eyes and her skin, it destroying crops and setting fires, and the insane ponies who cherished it's light.
As soon as Queen Nightmare Moon took back control of Equestria, Rarity's mother was taken and shaped into a maid. And after enough time spent with Rarity's father, Rarity was born, right into the servant class.
It wasn't that Rarity liked her job per se, but she did the best she could every single day. When she was a few years younger, the Queen had taken a bit of an interest in her.
It hadn't started out as much: a simple, small pay raise and allowance into the Queen's chambers. Of course, Rarity couldn't help but give herself to her Queen, but did not enjoy the time that they spent together. When they kissed, for days after Rarity could still taste the metallic flavor of the Queen's lips. It sent chills running down her spine.
"We need the money," her father told her. "It doesn't matter what she does to you. Do you know how many mares would do anything to be in your place?"
He was right, of course, about both things. Rarity's mother had fallen ill, and it would take more than a few thousand bits to heal her. Mares (and stallions) all across the Kingdom of the Night would kill for the relationship that Rarity had with the Queen.
"Miss Rarity," the Queen would call, "I've missed you, my love...Come here to me...
"Yes, my Queen?" Rarity called back, prancing to the royal chambers. "What can I assist you with?"
Rarity opened the door, smelling the heavy smoke that filled the room. Nightmare Moon lay on her bed, stretched out atop the covers. Rarity squinted, barely able to see. "Miss Rarity...Come closer..."
Rarity did as she was told. The Queen instructed her to lie down on the bed. Rarity did, and then the Queen lay on top of her. "Your Majesty..."
"Hush." Nightmare Moon kissed her, and Rarity tried not to resist. "Have you missed me?"
Rarity giggled. "Only every moment."
