~Three thousand years in the past~
“The moon is totally made of cheese! Discord said so!” Luna yelled as she stomped a hoof. Her tail swished in agitation.
“Nu-uh! You just blindly believe everything he says? What if he said that Dragons would one day be the scholars of the world! The moon is not made of cheese, Lu.” Celestia, the elder between the two, shouted back. She harrumphed and started walking away.
“Then I would call his bluff! The moon is too made of cheese!” Luna took off after her sister, intent on winning this argument.
“Is not!” Though they were fully grown, the two mares are still prone to childish sibling spats.
“Is too!”
“Is not!” With a war-scream, Luna launched herself at Celestia, and the battle was on.
~Present day Equestria~
Luna, snuggled into her sister’s side, looked back fondly on the lives they’d lived. “Hey, Celly?”
“Yes, Lu?” Celestia’s wing wrapped around Luna as she shivered from the cold winter air.
“You remember that one fight?” Luna’s voice was little more than a whisper.
Celestia chuckled. “You’re going to have to be a little more specific, Lu. I remember a lot of our little fights.”
“I meant the one where we fought over whether the moon was made of cheese or not.” Luna looked up to her bigger sister as her ears folded back.
Celestia nodded. “Ah, yes I remember that one. We both ended up in the infirmary, yes?”
Luna stayed silent a moment, enjoying her sister’s warmth. Celestia was content in letting Luna continue at her own pace.
She smiled up at her big sister. “Yes, we did. I now have a definitive answer to that argument. The moon is most definitely not made of cheese. It is a giant rock.” The smile faded, a frown taking its place as she whispered, “That means you were right all along, like with so many other things.”
Celestia’s eyes widened and her head whipped around from the stars she’d been looking at to her sister. “Hey now, none of that, Lu. Just because I was right in the end didn’t mean I knew it at the time.” She nuzzled Luna for a few seconds before continuing, “Besides, while you were confirming that I was wrong plenty of times.”
Luna looked skeptical. “Like what?”
“A big example that happened recently was Sunset Shimmer. She had the potential to become a great mage, but her lack of foresight and patience led to her turning down magic’s darker paths.” She sighed. “I had originally hoped her to become the Element of Magic, but that obviously didn’t pan out, and I thought for a few weeks that I would have to kill you…”
Luna nuzzled her sister’s neck. “But you did not have to kill me, Celly.”
“That doesn’t mean I didn’t think I wouldn’t have to kill you.” Celestia sniffled once. “My beloved little sister.” She sniffled again, shutting her eyes. “Then Twilight came along, and the rest was history.”
“And I am so grateful to you and her for freeing me from that nightmare…” Luna’s neck craned up and she nuzzled directly against her much larger sister’s cheek, before pecking Celestia on the lips.
Celestia’s eyes flew open in shock. “Luna! W-what was that about?”
“I have something to confess, Celly.” Luna shrunk away slightly at her sister’s expression. “I can’t bottle this up anymore. I… love you.” She shut her eyes and continued, “The real reason I fell and turned into Nightmare Moon was because I could not control my feelings. For you. I…”
Celestia drew her wing tighter about her sister. “How long, Lu? How long have you had these feelings?”
“I cannot remember a time without them, Celestia.” She blinked back a tear. “I would rather you know now so we can do something about it. I hat- I hate not being able to go to anypony about these feelings.” Celestia’s wingtip drew against her cheek and she winced as if it struck her.
“Luna, look at me.” Luna’s head raised only a few inches before Celestia’s mouth met her own again. Luna melted into their shared kiss. After a minute, Celestia pulled away. “Despite what you think, I don’t hate you, or find you disgusting.” She blushed and looked away. “I’m afraid I’ve had much the same thoughts, just not as long as you have.”
Luna blushed in time. “Y-you mean?”
“Yes, Lu. I love you too.”