Metal clinked against stone in a steady, if somewhat irregular rhythm. Celestia mused on this as she subconsciously tried to match strides with her shorter sister. It took some effort, but it was the easy kind of effort. No pony lives depended on her success.
"Do not implement this plan, Sister," Luna said in as commanding a voice as she could muster with her older sibling. "Nothing is to be gained from this venture!"
There was no answer, but it did not deter the fierce alicorn in the slightest. "We- I am certain we can find another way! These apes can not be trusted!"
Luna's efforts were in vain. Celestia was implacable. She had thought long about what she was about to do and it was indeed the only way. Humans were often greedy and untrustworthy, true, but they were not brutes. They understood the languages of diplomacy and negotiation. They understood money. Before the two worlds had collided, the ruling Princess of Equestria had considered the exact same plan, only with minotaurs or griffins in place of humans. She had always found the prospect too dangerous.
"We have been over this, Luna. Wherever I go, however well I hide, ponies find me. There is always another problem, another crisis. It has been a thousand years since I had a vacation."
She had stopped and tilted her younger sister's chin up with a primary feather. Yes, she was afraid. Of course she was nervous. In spite of those, Celestia was pleased to note, the wing was perfectly steady.
"Griffins, minotaurs, dogs - even the distant nations will not do. I am too well known on our world. But this new Earth; that has possibilities. The humans do not know me. I can be just another pony to them."
Luna was unconvinced. "But this is madness, Sister! Surely the tasks are not so onerous that they require escape? Surely I could take some of thy burden instead?"
The older sister grinned wryly. What the younger alicorn didn't notice was that ancient forms crept into her speech when she was flustered, or when she was lying. "We tried that too, remember? Once you came back I hoped - I really did - that you could take the throne sometimes. How long was it before a 'disaster' needed my attention?" Celestia signed the quotes around the word with her wings. It made Luna look away in embarrassment, but she answered nevertheless: "An hour."
"Forty-seven minutes, Sister. I had barely gotten into my bath before you were knocking on my door, panicking."
Now the night-blue alicorn blushed in recollection. "Thy insight is valuable, Sister." She looked up with new determination. "I shall try again! You can have your vacation whilst I handle the court! Give me another chance."
Her earnest plea made Celestia laugh pleasantly. She didn't blame her sister for the failures. She wasn't mad at Luna. If anything, her deference to her older sibling was flattering.
"The second time - correct me if I'm wrong - I was barely out of the throne room when you galloped after me."
Luna had remembered this, too, but the pony had been hoping that her sister had forgotten. She didn't have a reply, so she changed track again. "Surely, with your experience, ruling is not such a chore?" The smaller pony had placed herself physically in Celestia's path.
"My decisions save lives, Luna. Or destroy them. Even something as simple as breakfast has consequences."
This took Luna by surprise. "Surely breakfast is immaterial? What lives could be affected by the choice between toast and eggs?"
Now Celestia sighed sadly. It should not matter, but it did. When she had found out, the Princess opted to prepare her breakfast by herself from then on. "Different cooks prepare each. If I pick one over the other, one pony is happy, but the other miserable. Such heartbreak over such a simple choice. And each day is filled with them, Luna. I need to get away from it all, at least for a while."
Finally, the dark-blue alicorn saw there was no winning this argument. "How long," she asked flatly.
"Only a few months. A year at the most."
"And what shall I do in thy absence?"
"Rule. Make decisions. Tend to the sun and the moon. I have complete confidence in your abilities, Sister. You will chose correctly if the temptation to consult me is removed."
What Celestia didn't add was that perhaps, after a year of Luna's blunders, some ponies would finally come to respect just how much knowledge, effort and sheer gut feeling went into leading the pony nation. She had not lied - the alicorn believed Luna quite capable of handling all the 'disasters' her subjects usually brought before her. Perhaps she would even lose her patience a few times. Maybe it would reduce the amount of frivolous requests. If anything really big happened, Twilight and the Elements of Harmony would handle it, as they always have. Plus, they did not call Luna the 'Warrior Princess' for nothing. Even if every other pony in Equestria didn't agree, Celestia knew that day-to-day ruling wasn't quite that essential.
"Come, Sister. The human is waiting for us."
Slowly, grudgingly, the smaller alicorn stepped out of the way. She still didn't like the idea, but she would go along with the plan.