“You called, sister?”

Celestia poked her head into Luna’s bedroom. Like her own chambers, it was spacious without being cavernous. Luna had wasted no time filling her bookshelves and desk, and they were nearly as cramped with trinkets and mementos as Celestia’s. The layout was also similar—a bed nestled in one corner and a desk at the opposite one, with a large window in between. Aside from the color scheme, Celestia could have mistaken it for hers.

Luna looked up from her papers. “Yes, please, come in, Tia.”

“It has been a while since I was last in here,” Celestia said. “Normally you are in your office.”

“I had something to show you, and it seemed out of place there.”

“I see.”

Luna rose from her desk and crossed the room. She hunched under her bed, her tail rippled as she tried to extricate something from under the mattress.

Celestia stared idly at a piece of rock nestled between two books. Angular on one side and slightly rounded on the other, possibly a meteorite. That hadn’t been there the last time Celestia had been in Luna’s room. Of course, the room had been rather barren then; still new and under-filled.

“Well, what do you think, Tia?”

Celestia snapped out of her reverie, turned to Luna. Her contemplative mood quickly returned, however, when she saw what Luna was wearing.

“Do you like it?” The saddle looked very form-fitting. The straps matched Luna’s coat so perfectly, it was hard to tell they were there. The only thing to do was stare at the matte finish and curvy structure.

“Luna, that is a saddle.”

“Yes, I had figured as much.”

Celestia opened her mouth, but quickly closed it again. It was not often she had to search for the right thing to say. After centuries of diplomatic meetings and social gatherings, delicacy came easily to her, like eating or flying.

“You do not like it.”

“On the contrary, it looks lovely. Very well-made, nicely fitted.” Celestia bit her lip. “I know it has been a while, Luna, but did you happen to ask any of our staff about the social connotations of saddles, before you ordered one?”

“As a matter of fact, I did.” Luna took a few steps forward, and her sister noticed that her ceremonial barding had been taken off. “As I understand it, they are commonly fetishized.”

“That is one way to put it.” Celestia had trouble deciding what to do with her mouth. She wanted to frown, but various social blocks didn’t let her. The disapproval and the politeness fought to a stalemate, and she had to settle for a raised eyebrow and pursed lips in a ceasefire agreement. “Luna, you will forgive me if I am having trouble understanding why you would purchase a…saddle.”

“Tia, do you remember our conversation a few weeks ago?”

“I remember all our conversations. Down to the syllable.”

“Then you remember our discussion about ‘wincest.’”

“Indeed I do.” Celestia’s disapproval launched a valiant flanking maneuver, but politeness received last-minute reinforcements from curiosity. Her expression remained neutral.

“It gave me a lot to think about, you know. All the social mores and cultural trappings and alternate interpretations. ” Luna took a few more steps forward.

Celestia tried not to move, her legs as indecisive as her facial muscles. “I believe I explained my reasoning at the time. You seemed to understand why I had to let those fantasies be.”

“And you did. I do. But that was not the only matter.” Luna was only a few steps from her sister now. They were in the center of her room, right in front of the window. The moonlight caught in her mane, like sprinkles on ice cream or shimmers on a lake. “The unorthodox fantasies of our subjects made me think about other things.”

“Such as?”

Luna smiled. “I know you are a scientific type, Tia. Have you ever heard of the Westermarck effect?”

“I have.”

“It is such a simple theory. Elegant, really. And yet, as I was examining the latest research on it, I noticed a distinct bias among the research subjects.”

“That being?” Celestia asked.

“All of them were quite short-lived.” Another step. “Why, there was not a single test done on longer lived ponies at all.”

“Luna…”

“I never got to tell you, Tia.” Luna’s voice became a little quieter. “When the Elements freed me, when I first laid eyes on you after all those years, my heart leapt. The familiarity of my sibling after all that time was almost pure elation.

“But, once I reflected on it, you were not that familiar. Not in a bad way, of course. But you were different in so many little aspects. The curve of your back, the length of your mane, the smoothness of your fetlocks.”

“Luna—”

“Familiar, yet different. Comforting, but new. Beautiful, yet exotic. My sister, but not really.” Luna’s nose was only a few inches from her sister’s. “What could be better? It even has a scientific basis.”

Celestia’s face had collapsed into a grimace, surrender papers already signed. “Luna, this is ab—”

Luna put a hoof on her sister’s chest, and she could feel it recoil slightly. She leaned towards her sister’s ear, and she could feel Celestia’s neck inch away, feel the carpet shift as Celestia took half a step backward.

“Tia, I have to tell you something. Something I have been meaning to say for a long time.”

Celestia did not answer. The room was still.

Luna moved her mouth forward, exhaled just enough that her sister’s ear twitched, closed her eyes and whispered slowly, “Gotcha.”

The pillow struck her suddenly and sloppily. By the time Luna had picked herself up off the floor, Celestia was already halfway out the door.

“Who is uncomfortable with modern social situations now, sister?” she shouted. The door slammed shut.

Luna smiled to herself, unstrapping her risqué ornamentation. Her guards had been right; the elision had made the reveal that much more effective and thematic. She had not given them too many details, of course, but it seemed they had familiarity with modern slang after all.

Luna set the saddle on her bed. It would be rude to return a custom commission, but her personal finances could suffer the detraction. What was that expression her guards had taught her? “Totally worth it.”