Luna levitated the dark book towards her as she watched Twilight and her friends ride off back to Ponyville.
"Sister, are you sure that you can stop it? Everything the book has prophesied has come to pass. Why should she be any different?"
Celestia shook her head and sighed.
"I don't know, I just know that we have to try and stop it from happening."
The Lunar princess had never been very good at hiding her emotions, and the hurt she felt was apparent when she spoke.
"Why couldn't you have saved me then?"
Celestia looked over to her younger sister, and saw the tears forming in the corner of the dark alicorn's eyes. When just the two of them were alone together, there was no need for them to hide their feelings from the world, yet Luna still insisted on keeping all of her sadness to herself.
"Oh Luna." Celestia sighed, embracing her sister in a hug "I tried Luna, I really did, but you wouldn't let me. You kept your emotions bottled up, just like they are now, and I couldn't see the darkness that was eating away at your heart until it was too late. It's okay to express your feeling Luna, you just have to be...careful...with them when interacting with the public."
Tears were now flowing freely down the princess of the nights face. Despite her sadness, she continued the conversation in between her sobs.
"What if...What if she can't be saved?...just...Just like me."
Celestia held her sister for a moment longer, before releasing her from the embrace.
"Then we have to be prepared for what is to come."
Luna waited for her tears to stop, before she mentioned her fears to her older sister.
"What was the point of the test you gave her?"
"Exactly what i said it was, to see if she was ready for the next step."
"And what have you decided?"
"I already told her that she had passed."
Luna gave her sister a quizzical look, one that saw through her half-truth and demanded a real answer. Celestia only sighed at the lunar princess's stubborn persistence.
"I'm going to let her continue to the next level."
"WHAT?"
The force of Luna's shouting accompanied by an accidental use of the royal canterlot voice was enough to almost blow Celestia off the balcony. After stepping inside the castle, and having Celestia soundproof the room, Luna continued.
"Why would you do that?"
"She saved the crystal empire, and even though spike helped her, she put the needs of the many above herself. Such is not the act of our destroyer."
"She wasn't supposed to pass the test!"
Celestia winced as she felt the soundproofing spell break. Luna, paying attention to it despite her anger, lowered her voice and attempted to stop shouting. But the rage in her words was still just as evident.
"She was supposed to fail. Nopony could have saved them but us. Nopony else knows the dark magic that Sombra used. She couldn't have passed gotten past the false door unless she could cast it."
"But she didn't give into it, if she had then she would have been stuck there forever. We enchanted the door that way...remember?"
"She had Spike with her, You told her to do that task alone, and she brought Spike. Spike would have snapped her out of the enchantment, how else do you think he managed to end up being the one to save the day?"
"Twilight could have simply given the credit to him..."
Even to herself the idea sounded ridiculous, they had placed that final trap in place to turn the dark energy in a pony against them, and from the events they had witnessed transpire through the eyes of the fake king Sombra that had been 'attacking' the town, there was plenty of dark energy to spare inside Twilight.
"No Celestia, both of us saw the extent of the darkness inside of her. We can't let her get stronger until we're sure that it's not going to be a problem."
Knowing that the argument was hopeless, Celestia went on the offensive.
"What do you suggest i do then Luna? Just tell her, oh sorry about the whole sending you out to a crystal empire that was secretly keeping their true forms withheld in order to make a test. Sorry about making a fake sombra attack it and everything, and about making you have to witness your worst fear come true, but we've realised that you're actually a evil mare consumed by darkness prophesied to destroy the world and because of that I have to make your worst fear come true. Do you really want me to do that to her Luna?"
"Of course I don't! But we can't just let her continue like this, she's already almost as powerful as I am. If she continues like this, nothing will be able to stop her if the prophecy comes true!"
"Then what do you suggest I do? Because unless you haven't noticed, Its either we break that poor mare's heart, or we keep her close and try to change her fate!"
The two sisters were glaring daggers at each other, noses pressed up against each other as they belted out their words. As the door opened into the chamber the alicorns were in, both of the ponies turned to see a nervous looking guard trembling as he stared at the two royal sisters.
"WHAT IS IT?"
The two sisters yelled out in unison, Only just realising that they had begun to use the royal canterlot voice once again. The trembling guard replied in a weak voice that seemed just as nervous as he looked.
"S-sorry to interrupt but...um...the younger sisters guards would like to know why she felt the need to disturb their sleep with 'such an horrific array of sound'. Not my words your majesty, theirs."
As the pony slipped back out into the hall, closing the door behind him. Luna sighed to herself, before abruptly stopping and addressing her older sister.
"Damnit, now you've got me doing it to."
Despite the unresolved argument still between them, Celestia let a smile colour her features.
"It comes with the job."
