The seven ponies remained in the Crystal Empire for a week, rationing out the food that Haven had sent them with to make it last a few days longer. Sunny hardly left the library, and Izzy remained at her side - the unicorn rarely left her. By the second day, the entire palace was unfrozen, and Flurry was working on the streets. Zipp and Pipp flew around, exploring rooms and finding random things that they thought would be interesting to bring back home and study. Hitch and Sprout were given the fun and time-consuming task of figuring out how to fit these new things in the packs that they had brought. The royal sisters found tons of items, but it was the day they left that Sunny found the absolute greatest discovery ever.
Nopony else was awake other than Sunny on that very early morning, and the mare walked the now-familiar path to the library in slightly lower spirits than usual. Every night, she had the dream about being trapped in a swirling wall of wind as images from her life flashed in and out before her eyes. The voice would come and propose that Sunny let go and hand control over to it, and she always refused, focusing on the glowing star that was her ancestor’s cutie mark. Last night, however, she’d had a significantly harder time resisting the voice, and it scared her.
Sunny might have been acting like her old self again, but she still had a bit of a faulty memory, and she felt the voice’s presence in the depths of her head, waiting to attack again. Izzy promised to keep everypony safe, Sunny thought to herself. No matter what happened, her friends would be safe.
Like always, the library glittered with leftover sheets of ice. She and Flurry had decided to defrost this room one book at a time, worried that the paper might catch on fire, and there being so much of it, this could be a big problem. Flurry had experience with this - one of the rooms she had defrosted had a scroll resting on a desk, and a corner of it caught on fire when she did her spell. Now they unfroze paper products separately.
Sunny took a deep breath and breathed in the smell of old paper, leather covers, and musty ink - it always seemed to calm her down. Maybe because it reminded her of her father, who always smelled like that. Maybe because her ancestor was said to be a bookworm, and she had inherited the trait. She closed her eyes and thought of her friends, though the memories were harder to access than normal. Fighting down the panic, Sunny felt a tingling sensation start in her heart and spread to the rest of her body until her golden wings and horn returned once more. She spread her wings and soared to the spot where she’d left off and continued to scan the shelves for books that might help with her current predicament.
It must have been fifteen minutes before she noticed that a few of the books had been pushed aside, revealing a horseshoe bolted to the wall. This in itself was not overly surprising, but when Sunny looked closer, she saw a moon, a sun, a heart, and a six-pointed star carved around it…
Intrigued, Sunny inserted her hoof onto the horseshoe and felt something unlock beneath it, some sort of mechanism. Acting upon instinct, she twisted it to the right, and the entire shelf slid to one side, revealing a long, dark tunnel that twisted out of sight. Sunny took a hesitant step forward, then another, then another, until she was briskly trotting into the tunnel. The bookshelf slid closed behind her, but she wasn’t afraid. Though the tunnel was dark, her glowing wings and horn provided all the light she needed.
Finally, she rounded a corner and came into a large room that was just as dark as the tunnel, except for a large circle on the floor, glowing a dim white light. Sunny stepped onto the circle, and it lit up, turning into a perfect, glowing replica of her cutie mark. She felt a wave of magic rise around her, lifting her mane off her shoulders a bit before it spread to the rest of the room.
The room lit up, and Sunny gasped. Around the room appeared four beautiful stained glass windows like the ones back in Zephyr Heights, these of four beautiful ponies with wings and horns and very familiar faces.
A white alicorn with a rainbow colored mane in front of a rising sun was next to a dark blue alicorn with a mane that sparkled like the night sky, pictured in front of a circle that displayed all the moon phases. In the direction that Sunny just came from was a candy pink alicorn with a purple, pink, and yellow mane in front of the very castle that her friends were now in, and next to that was a very familiar purple alicorn and a beautiful castle made of crystal.
A beam of light stretched out from where Sunny stood on the floor and connected with the area between Twilight Sparkle and Cadance, and a new window appeared, but this one of Sunny. She was standing in front of her lighthouse - but it didn’t look like her lighthouse. It looked like it was made of some holographic rainbow material, with the shape of the three unity crystals above the door. Her golden wings were spread and her horn glowed.
“Wow,” Sunny whispered, stepping forward to see it better. She gently laid her hoof on the window, but instead of feeling hard glass, like she expected, the window appeared to be made of nothing, since her hoof passed right through.
Sunny jerked her hoof back and held it against her chest. What was that?
“It’s amazing, isn’t it?” said a voice, and Sunny whirled around to see Flurry walking through the picture of Cadance. “I was wondering how long it would be before I discovered this place.”
“What is it?” Sunny asked as Flurry stepped on Sunny’s cutie mark. It glowed and turned into Flurry’s mark, a blue shield with a heart displayed on it. A line stretched from Flurry to an empty space between Cadance and Celestia, turning into a beautiful picture of her standing in front of the Crystal Heart.
“The Hall of Princesses,” Flurry said, joining Sunny at her picture. “It’s a kind of netherworld that connects the homes of all princesses - see, that one leads to the Crystal Empire,” she explained, pointing to the picture of Cadance. “And, well, I suppose that one would, too,” she added, looking at hers. She pointed to each window as she named off the places they would lead to. “Canterlot - Zephyr Heights, I guess - I believe that one leads to the Castle of the Two Sisters - or what’s left ot it, anyway - and that one leads to Twilight’s castle in the Everfree Forest.”
“How do you know all this?” Sunny asked, experimentally waving her hoof through her picture and seeing if she could feel anything on the other side.
“My… mom told me about it,” Flurry said, looking at the giant image of Cadance. “She wanted to take me here, but every princess must discover it on their own right. Other ponies can enter it when the door is open, but only a princess can open the door.” She noticed what Sunny was doing and laughed. “I think yours might lead to your lighthouse, Sunny.”
“Cool,” she whispered.
“Sunny? Flurry? Are you - woah.” Zipp broke off as she stepped into the room. “This is… what is this place?”
She stepped on the glowing circle, and a new window appeared between Twilight’s and Luna’s. Flurry explained what the Hall of Princesses was, but Sunny suspected that she wasn’t really listening.
“What’s going on?” Sunny asked the pegasus.
“We couldn’t find you guys, and we were starting to get worried,” Zipp explained, finally tearing her eyes away from the picture of her in front of modern Zephyr Heights. “We should go back before they start freaking out more.”
The three princesses passed through the picture of Princess Cadance just to be safe and emerged in the library, where they found Pipp hudled on the floor, crying, with Izzy and Hitch at her side, comforting her.
“Pipp?” Zipp ran forward and reached out to her sister, but Pipp flinched and recoiled, so Zipp backed up. “What happened?” she asked Hitch.
“She tried to go in after you,” he said in an undertone, patting Pipp on the back as tears poured out of her eyes. “But it wouldn’t open.”
“Oh.” Zipp turned back to her sister. “Pipp, I’m sorry, I-”
“Sorry for what?” Pipp snapped, standing up and glaring at her sister. “Sorry that you’re so amazing and awesome and act like you’re so much better than everypony else? Sorry for all the times you’ve got Mom’s undying attention and left me alone without anypony at all? Sorry for acting like you’re oh so sick of me?”
“I do not act like I’m better than everypony else!” Zipp retorted. “In fact, you’re one to talk, Little Miss Perfect, who becomes the first topic that everypony - including Mom - ever thinks about! Do you know how many times Mom’s told me, ‘Your sister’s doing something useful with her life, your sister’s putting her talants to good use, your sister doesn’t disappear for hours upon end each day, your sister doesn’t obsess over flying, your sister’s fine with lying to the entire kingdom!’ ”
“I was only doing what I had to do to get ponies to remember that I existed!” Pipp screeched, taking a step forward. “Because nopony seems to remember that there’s another princess, oh no, they just care about Zipp this and Zipp that and Zipp, Zipp, Zipp, and you don’t even care! You let them talk about you like you’re the only pony in this world who actually matters!”
“At least I’m not a selfish, self-entitled perfect little princess!”
“Well, neither am I!” Pipp geastured wildly to the bookcase, which had slid back into place. “And I’m sick of you treating me like one!”
“I’m sick of you being one!”
“I’m sick of being your sister!”
“I’m sick of being your sister!”
“UGH, you are the worst!” Pipp whirled around and marched behind some bookshelves. In the silence that followed, Sunny could hear her quietly crying again. Zipp groaned and spread her wings, flying out of the room and slamming the door shut behind her.
“...Suddenly, I don’t think I want siblings anymore,” Izzy said into the silence.
Sunny sighed. “I think we should leave today. It’s about time, and now we have a much faster mode of transportation than walking for days on end.”
“Really?” Izzy asked, tilting her head at the shelf behind them. “Where does that tunnel lead?”
“We’ll show you,” Flurry offered, turning back to the wall. She paused at 90 degrees and looked at the bookshelf behind which Pipp was hiding. “Uh, Pipp… you want to come and see?”
There was a pause, and then the pegasus slowly walked out from behind the wall of books, her eyes bloodshot, red, and puffy, and her mouth set in a grim line. Her mane was slightly frizzy, but she walked over to where the other ponies were standing. Flurry was about to twist the horseshoe and open the door when the library doors suddenly burst open again. Sprout was standing in the doorway, Zipp behind him. He held out a sealed scroll that bore the crest of Zephyr Heights.
“I think you should see this,” Sprout panted, his breath coming out in short gasps.
“What is it?” Pipp asked, sounding genuinely curious. She noticed Zipp hovering behind the stallion and her eyes narrowed.
Zipp raised her head, and her eyes met Pipp’s, and the younger pegasus was startled to see that they were empty of anger and filled with something she rarely saw in her sister’s eyes: fear. “It’s from Mom,” Zipp said. “I think… I think something might be wrong.”