The third time Luna visited her sister was one week after Celestia had taken back her sun. It had been bad, very very bad. But then it started to get better. Not much better, but a little. Meals came back slightly touched, Spike was able to visit more and more. Luna would have left it, but that morning she had seen Dip Quill leaving her sister's chambers. Someone other than her and Spike having been allowed direct contact with the princess had probably been the biggest leap forward thus far.
When she had seen Spike enter shortly after, Luna had headed to the door. She breezed past the guards who had largely become a formality at this point and lingered there, unsure about whether to head in or not. It was when she'd heard her sister laugh, a delicate musical sound that reminded her of wind-chimes, that she first knew someone could come back from the dead.
Her hoof hovered at the doorknob but she immediately dropped it when she heard that laugh again. This could wait until later tonight. Luna walked back down the hall quickly, before exiting through a balcony. Her wings beat as she flew toward her own tower. It would not do for the guards to see their princess cry.
"Come in Luna," her heart worked overtime to hear Celestia call her in, almost as if nothing was wrong.
"How did you know it was me?" she asked as she entered.
"Dip Quill apologies every time she knocks, poor thing, and Spike scarcely bothers knocking at all now."
"I saw him visit today, the two of you sounded..." the unsaid word lingered for a moment. Finishing the sentence with 'happy' or 'normal' would have been inappropriate at best, insulting at worst. Celestia didn't seem offended, however, and carried on clearly understanding what Luna was so desperate to imply.
"We talked a lot, he has so many stories from before we..." to her credit, Celestia didn't lose her composure as her eyes misted and voice cracked slightly, "Do you know, all her friends asked for eight revisions on those Grand Galloping Gala dresses?"
She smiled despite the tears on her cheeks, normal was definitely the wrong word and they both knew it.
"You two sounded better," Luna offered. Both her sister's smile and tears grew. She wanted to go over there and comfort her, but Luna was scared about whether she could remain strong enough. She had been weak on her last visit and guilt had remained since. The thought of the conversation she knew she had to have made her feel sick, but could anything be worse than this? Both stood, one crying, the other rooted to the ground.
"I'm sorry Celestia," she began, not giving herself time to consider whether this was right or not, "Seeing you the way I did scared me more than I could believe. For just a minute, it... felt good to feel like you were just my big sister and I had a bad day and was crying about that."
Luna winced at Celestia's expression, the clear concern and desire to comfort wounding the younger alicorn. She wasn't here to force her own issues onto Celestia, not again.
"But that was selfish of me, and I'm sorry. It doesn't do for me to be weeping in your arms like a foal while you're going through this."
"I've not had a single dream since... Not a single one, I wonder how difficult it is to maintain that in an alicorn of all creatures," even in this state, there was no fooling her older sister. Luna felt guilty at the small note of pride that bubbled up upon having her efforts recognised. "I know this is hard on you too Lulu, but I know you're trying. You don't need to feel guilty about wanting some comforting."
"I'm not as good as Spike at this sort of thing," she immediately spoke, hoping for all the world her sister wouldn't be able to hear the lump in her throat, "So instead, I thought about whether it could be approached like finding tangible solution to a problem,"
"Rarity is gone Lulu, I don't know if that's a problem you can solve," the moon princess suppressed a small gasp at hearing Celestia verbally acknowledge the situation for the first time. Still, her expression didn't match her words, she looked expectant, as if the sheer awfulness of reality was enough to make her believe the absurd alternative that Luna could have found the solution to her lover's death.
As it happened, Luna had maybe done just that.
"What I am about to suggest... is not ethical. Many would call it an unforgivable abuse of power,"
"So why are you suggesting it?" There it was again, the look in Celestia's eyes. It did what she couldn't, and screamed at Luna to carry on and finish the damn idea.
"Because you're my sister, and ethics can hang if I can stop you feeling this way." Celestia seemed to consider Luna's words for a minute. She made her way to the bed and looked at her picture again. Seeing Rarity's expression seemed to make her mind up, just as seeing Celestia's had made Luna's. She sat and patted a space next to her. It looked like they'd hang ethics together.
"Do you remember when Twilight Sparkle went back in time?" The two of them had made themselves more comfortable.
"Yes of course, she terrified herself." Celestia recalled with a faint smile.
"The spell she found was for travelling time, but it wasn't the only research Starswirl did into the matter. It would seem towards the end of his life, he found a way to displace it." Her sister gave Luna a questioning look, prompting her to continue, "Displacing would allow the user to shunt the entire timeline using themselves as an anchor. It eliminates you from time entirely, then reinstates you at a different point. In practise, it avoids the issue with you meeting your past self because there wouldn't be a past self, there would only be the present you in the new present you make."
Comprehension finally dawned on Celestia's face.
"I wonder how it is that I never heard of this?"
"Come now sister," Luna began, allowing herself to tentatively smirk, testing the waters between them, "We both know that spending hours looking through dusty old archives was never exactly your favourite activity."
"Correct, but we knew someone who's favourite activity was just that, how was it that Twilight never knew of this spell?"
"Oh she did, I recall she had a nightmare once about using it and accidentally going back too far and never getting to meet her friends. Once I had calmed her down I let her give me a lecture about how Starswirl had arrived at it by modifying his original. Suffice to say I didn't get to check anymore dreams that night"
"That certainly does sound like her," Celestia laughed, and Luna's heart swelled again. She chanced a hope that the wound was less raw than a week ago, "Do you know if she ever used it?"
"There's every chance she could have used it and we would never know. But we know Twilight Sparkle wasn't a pony that sought any kind of great power, she just loved the elegance of the theory put into practise, that's why I never minded that she knew all of these dangerous spells. However, what's interesting is given how much more intense it is than just simply placing yourself somewhere else on the timeline temporarily, Twilight would've probably only been able to manage a few days at most... but you are not Twilight."
If she was shocked, Celestia didn't show it. It would be difficult for someone to be unable to predict the end point of this conversation, and Luna wasn't so deluded to think someone as perceptive as her sister didn't know what she was about to propose.
"How far back could I go?" she asked, sounding much like she did when she was teaching.
"I... well, is this you want?" Luna tentatively replied, feeling like they had skipped a crucial part of the conversation.
"Luna, when I sent you to the moon it nearly destroyed me, but I always knew you'd be back. But Rarity won't be back, no-one is ever going to see her again." The sun princess' shoulders slumped and she trembled, "I can't do this, I wasn't ready. No matter how ready how I tried to be, it didn't do anything."
Luna's wing found Celestia's back again, but this time she didn't allow herself the chance to break down. She remembered how destroyed she had been with each element's passing. When Twilight died, she didn't ever think Celestia would recover, but she did. She would have always have faith that her sister could come back from anything. So why was she even suggesting this?
The truth was, she knew the answer and it scared her. Not once in her entire life had she seen her sister like those last two visits, not once.
"I know it might seem like it's getting better Lulu but... just being able to talk to ponies again takes so much work and I'm so tired. I still feel as bad as I did the second it happened, I'm just getting better at hiding it. I'm sorry to say it. Sorry to put it one anyone else, especially you, but I meant what I said to you, and I still do," Celestia turned to face Luna, who tried to conceal her heartbreak, "If I could, I'd go with her."
How easily doubts can disappear in the face of an admission like that. Luna took her sister's hooves in her own, she knew what burying everything down did to you. She wouldn't let it happen to Celestia, the world would burn before she did.
"I think you could manage a few years."