Twilight wasn't sure if it was better or worse that they left through the door, and not the breach Luna had smashed through the side of the bar. They ambled down the streets of Ponyville, in what Twilight hoped was the vague direction of her castle.

“Gives a whole new meaning to 'Hole In the Wall,' get it?” Pinkie Pie nudged Twilight, and broke down into helpless giggles.

“Hah! A merry jest.” Luna said, and took a swig from a bottle of rum.

Twilight winced at the pun, and then again as she saw Luna carting a bottle about. “Where did you get that?”

“Spoils of war.” Luna smiled, showing gleaming white, nigh-predatory teeth.

“But … but we're not at war!” Twilight said.

Pinkie Pie, in the meanwhile, neatly took the bottle from Luna and swigged without breaking stride. “That's okay! It's not spoiled, either!”

“... I'll just add it to the repair bill.” Twilight said, looking over her shoulder, just in case an angry bartender were to come chasing after her.

“Still don't see why we had to leave.” Cadance grumbled. “That barely even counted as a fight!”

“A very thorough thrashing.” Luna said, with no small degree of pride in her voice.

“I think one fight is enough for an evening.” Twilight said. “Besides, I really doubt anypony's going to even come near us after what you did back there.”

“The night is yet young!” Luna said.

Something above their heads squeaked, and the four princesses (plus Pinkie) looked up. A sizable bat flapped down out of the sky on leathery wings, finally coming to land upon Luna's swashbuckler hat. It dangled upside-down from the hat's brim, directly in front of Luna's eyes.

Luna merely nodded, and used her magic to levitate a tiny scroll from a case on the bat's leg. She unrolled the strip of paper and and read it silently-- though there was a subtle shift in her stance as she did so, as she stood a little taller, a little more ready.

“'Twould seem,” Luna said, looking up from the message, “there is a Phantasm of some sort marauding about the dreamscape. A foe not much more powerful than those scoundrels we trounced earlier this evening, but a pest that requires dealing with, nonetheless. Would any of you care to accompany me on this task?”

“I think I'll pass.” Twilight said, and cast a worried look at the rest of her friends. What kind of trouble would Celestia and Cadance and Pinkie get into without her supervision?

“Sounds fun, but I've gotta work tomorrow!” Pinkie Pie said.

“You always enjoyed flying alone on your dream-jaunts, Luna.” Celestia said.

“And I'm kinda drunk.” Cadance belched loud enough to rattle nearby windowpanes. “Okay, maybe a little more than 'kinda.'”

“In that case, I bid you all farewell.” Luna bowed, courtly and gallant. “'Til we meet again!” she said, and took to the sky. Magic crackled over her sleek body, and she disappeared in a burst of moonlight.

“Guess I'd better get home too!” Pinkie Pie said. “Big batch of cupcakes to bake tomorrow, so I'd better rest up! Byyyyyye!” The pink pony set about bouncing away down a side-street, back towards Cupcake Corner.

“And then there were three.” Princess Celestia said.

“Don't say that!” Twilight blurted, only to realize she'd tried to give commands to an immortal sun-princess. “I mean. Uh. You might not want to put it like that, because that almost makes it sound like we're getting killed off one by one.”

“Been reading parlor mysteries again, Twilight?” Celestia said.

Twilight scratched at the back of her neck, embarrassed. “Maybe?”

“Shoulda stuck to the smutty romances.” Cadance said.

The rest of the walk back to Twilight's castle was uneventful, except Cadance's singing.

Twilight winced as Cadance belted out another filthy verse of “Oh Roll Your Leg Over (It's Better That Way).” If nothing else, Twilight mused, Cadance's voice could scare off any nocturnal predators through sheer volume alone.

Optimism.

By the time she pushed open the doors to her castle, Twilight's hooves were aching, her head was throbbing, and her eyes were bleary from the night's misadventures. She made it a point not to look at the clock-- she already knew she was way, way off her normal schedule. Knowing exactly how late it was would only make her feel worse.

“I don't know about you guys, but I'm exhausted.” Twilight said. “I mean … I guess this has been fun, but I'm sure you two have lots of important stuff to do tomorrow.”

“I believe you're right.” Celestia yawned, and daintily covered her mouth with one hoof.

“That's it? Pssh. Lightweights.” Cadance said. “Back when I was in college, there were nights I didn't get to bed 'til the sun came up!”

“Which is something Princess Celestia has to tend to tomorrow morning.” Twilight nodded.

“Oh. Right.” Cadance said. “Well, I guess you can go to bed, but I'm gonna--” In the early-morning quiet of the castle, the burbling noise from within Cadance's stomach echoed off the walls. Her pink complexion shifted to more of a green tone. “--I'm just gonna go find a bathroom.” And Cadance bolted down the hallway.

“Third door on the left!” Twilight called out, thankfully.

Cadance barged through said door-- and a moment later, Cadance's retching echoed through the normally quiet halls of the castle.

Twilight hoped Spike was asleep by now.

“I'll look after her.” Celestia said. “You go on and get to bed.”

“Oh! I couldn't!” Twilight said. “I mean, you're my guest! If anyone's going to hold Cadance's mane while she's sick, it's going to be me.” She nodded, resolute.

“Very well then.” Celestia said, in the sort of tone that made Twilight beam with pride. “In that case, I'll be getting to bed.”

Twilight nodded. “My room's just down the hall--”

Princess Celestia arched a brow.

“I mean! Uh. You can sleep in my bed!” Twilight blurted, cheeks going crimson. “Without me in it, that is! You know, like how in medieval times whenever a feudal lord visits one of their vassals, that means the lord gets the best bedroom in the castle, and everyone else just shifts down a notch. Thankfully it's just me and Spike here so it's not like we don't have extra bedrooms, so it all works out!”

“I appreciate the thought, Twilight, but a guest bedroom will do just fine, thank you.” She smiled, and trotted down the hall. “Honestly, I'd even settle for a couch at this point.”

Twilight opened her mouth to protest, but soon she heard Cadance again, and shook her head. At least it sounded like the worst of it was past.

Optimism.

Princess Celestia woke with a pain in her neck and a top hat pulled down over her eyes.

She groaned, and rolled off the couch she'd sprawled upon. It had seemed a good idea at the time, to sprawl out on the couch in a way totally unbecoming of a princess, the sort of thing she could never get away with back in Canterlot. Sadly, the couch she'd chosen to sprawl on wasn't scaled for ponies of Celestia's stature, and so she'd spent those fitful few hours of sleep with her neck bunched up at an odd angle against the sofa's armrest.

Celestia slowly rolled off the couch, feeling entirely too many of her joints pop and crackle in protest. She shook the top hat off of her head, only to immediately wish she hadn't as she got an eyeful of morning sunlight.

Wait.

“Good morning!” Twilight trotted into the sitting room, levitating a platter with two steaming mugs of coffee balanced atop it. “Did you sleep well?”

“Well enough.” Celestia picked up a mug of coffee and took a bracing sip. Twilight had put far too much (read: any) milk and sugar in it, but at that moment, Celestia knew she needed the caffeine. She studied Twilight for a moment-- the young princess looked a little tired, but she stood prouder and smiled wider than she'd ever seen her favorite student do so before. Even if the very tips of her wings appeared to be singed.

“Great! I know this probably isn't as nice as things are back in Canterlot or even the Crystal Empire, but I'm really glad you guys stayed over. Cadance is still sleeping off her hangover-- I made sure she drank a bunch of water before she went to bed, so I'm sure after she has a little orange juice and gets in a hot shower, she'll be fine!”

“Good to hear.” Princess Celestia glanced to the sun streaming in through the window.

Twilight followed Celestia's gaze, and perked her ears up. “Oh! I almost forgot! I need to thank you!”

Celestia blinked, and drank down some more coffee.

Twilight went on without prompting. “When you and Luna and Cadance just wanted to spend the night going out drinking and fighting and singing and stuff, I was kind of concerned! But now, I see you had something in mind all along! You took me out of my comfort zone to push my limits, just like when you told me I had to move to Ponyville.” Twilight trotted over to the window, and spread the curtains wider, causing more bright morning sunlight to stream in.

“I was going to wake you up a lot earlier, but when I saw you sleeping on the couch so peacefully, I realized that you were really just testing me! You and the other princesses willingly (if safely) incapacitated yourselves so that nopony was around to raise the sun in the morning … except for me!” Twilight laughed a little. “It was really, really hard, and I miiiiight have gotten a little too close to the sun in the process, but it was worth it!” Twilight puffed out her singed wings, and looked up at the clear blue skies outside with no small degree of satisfaction. “So now we all know Equestria will stay safe and sunny in case anything ever happened to you. Which it won't, I know, because you're so strong and wise and powerful! But, you know, the next time you want to take a vacation, or just sleep in a little bit, I've got you covered!” Twilight turned back to Celestia. “Just, um, maybe give me a little warning, next time?”

Celestia looked down at her coffee. Then out the window. Then to her smiling student. Then back to her coffee again.

“Yes.” Princess Celestia said. She forced herself to sound her normal gentle, serene self, despite the ache in her neck and the throbbing behind her eyes. “That's exactly what I had in mind. Good job, Twilight.”

Of all the things Princess Celestia had taught her favorite student, she was glad that lie detection wasn't one of them.