It was almost imperceptible the changes to their barren path. Ever so slowly it changed from just normal rocks to something more ruin-like. The dry ground was replaced with shallow water, soaking through their boots. It wasn't long before Yuki could tell they were standing in the ruins of a city.

She ran a hand along a wall, staring around her. It was unlike anything she had seen before. Still simple, the buildings were all made of stone. But something felt off about the world. Strange letters were carved into the walls surrounding murals of what looked like great statues. Whatever it was Yuki couldn't make heads or tails of it.

"What is this place?" Yuki asked, looking around once again.

"I don't know," X said. He was staring at the letters, tracing them as his mouth moved.

"Second time." Yuki and X both looked up at Y. She stood with her arms crossed as she looked around the ruins. She glanced away from their gazes, seeming unnerved. "I mean, this is the second world we haven't recognized. So, why bother?"

Yuki frowned. She had a point. Like the last one, she had no idea what this world had been. It didn't give her the same feeling of dread she imagined it would if she knew the world. So what was their point?

"They must have some kind of point. Aryum isn't random," she said. Her gaze once again turned to the entire ruin. It had to have been a city at some point. Though now they appeared to be at the edge, more spread out before them.

"Yeah, but she certainly won't make it obvious," X said with a sigh. He turned his attention back to the writing on the walls. "It'll probably take a few more worlds before we see some kind of pattern."

"Ok, first thing first then," Yuki said, she turned her attention fully onto Y. "Y, we need to find the lights remnant."

"Oh, that sounds fancy," Y said with smirk. Yuki looked away before she could see anything else. It just seemed like the right thing to call the remainders of light. It was certainly easier. "I like it."

Y paused for a moment, resting her hand over her heart as her eyes closed. Yuki waited silently, not looking away from Y. X seemed to be only mildly interested, still looking at the walls more than his sister. His hand was jumping from place to place, matching symbols and patterns to one another. 

"It's this way."

Y turned and led the way through the ruins, her footsteps sloshing through the water. The sound seemed to attract Heartless, a kind Yuki had never seen before. They were a dark blue of sorts with something like wings on each side and blue tentacle-looking things underneath them. What was most annoying was the way they wove in and out of the water itself, exploding out with enough force that the water droplets stung. Even so, the three of them managed to dispatch them easily enough.

A pause in the Heartless gave the three elites time to recover. Yuki could only keep her eyes scanning the surrounding. X was back to where he always seemed to be, at the walls where the strange letters were. Y was looking around as well, her arms wrapped around her tightly.

"What do you think this world was called?" Y asked.

"I have no idea," Yuki said with a shrug. Glancing at Y she could only frown. "Is something wrong?"

"It just seems, familiar I guess," Y said, biting her bottom lip. Her eyes scanned the surroundings, trying to find something that Yuki wasn't sure even existed.

"I think it's Atlantis," X said suddenly. Yuki looked over at him with a frown. She had heard of that place before, hadn't she?

"Do you mean Atlantica?" Y asked. Yuki was familiar with that world for sure, at least from Sora's stories. She had never visited and honestly wasn't sure she wanted to. But it wasn't the same as the stories she was thinking of. Old islands tales.

"No," X said quickly. "I just, um, these writings. I'm pretty good at languages, so I can kinda read them. A lot of them are praising some guardian of Atlantis." He explained as his hands still traced around the symbols carved in the walls.

"Huh, Atlantis," Y repeated the name slowly. As if saying the name would explain the off feeling she seemed to have.

"I've heard stories about a place with that name," Yuki admitted. The twins both turned to look at her. She shrugged, rubbing the back of her head. "It's considered a legend to most other people, an underwater city. Some say it was really advanced. But, it's a Lost empire." People on Destiny Islands had told the story. Sora had once talked about finding Atlantis on their adventures when they were children. But Yuki hadn't thought there would be a world like the stories.

"Lost Empire," X echoed.

"Like Scala," Y whispered. Yuki frowned, her attention turning back to Y.

"Scala?"

"Scala ad Caelum," X said calmly, as if that was an explanation. Yuki frowned at him. It didn't even sound familiar.

"It was once called the keyblade capital," Y explained. "Master Eraqus didn't talk about it a lot, but it's where he was from. A lot of wielders used to be trained there. But now it's abandoned. Some tragedy."

Yuki nodded slowly. It was amazing to think of a world purely for keyblade wielders. It seemed so familiar and warm to her. But at the same time, she knew she had never even thought of such a thing. There weren't enough wielders for it. Not any more. And she wasn't sure it would be a good idea for so many to exist at once. All she could think of was the graveyard filled with keys.

"Maybe that's why they picked this world," Yuki said, tapping her chin. Y looked at her with a tilted head.

"Huh?"

"Well, think about it," Yuki said. "They keep dragging up the past, maybe they wanted you to think of this Scala place." It was another tie to the past. To the old master Y had lost. Another way to shake them to their core.

"That's a possibility," X agreed. "Tayressa would have called Scala home at some point in her life. She did train with both Master Eraqus and Xehanort. So now that's our past and theirs."

"She trained with your masters?" Yuki asked. Her mind was racing. She had known Tayressa had once had a keyblade. She had known she had had companions she had lost somewhere along the way. But Master Eraqus and Xehanort. The ones who had trained X and Y.

"Yeah. She didn't mention it often, but sometimes she compared me to Master Eraqus," Y said, shrugging slightly. The thought seemed to put her off as she pouted just slightly. "Is that a problem?"

"Back when I had first joined the organization, Tayressa would take me to Destiny Islands on recon. She told me a companion of hers was from Destiny Islands," Yuki said, the words leaving her mouth before she had enough time to think it through. She hadn't put much thought into it before. But now alls she could do was think. Which one had it been?

"Did she say who exactly?" X asked.

"No, just a friend," Yuki said.

"It was Xehanort."

Y spoke with certainty that surprised Yuki. How could she know that? Had Tayressa told her.

"What? What makes you so sure?" X asked. Yuki was glad he was on the same page as her.

"Master Eraqus was born in Scala. He told us that much," Y said calmly. "So, Xehanort is from the same island. The same world. This has to play into their hands. There's too much from this one coincidence. Aryum would have seen this coming, at least."

"Depends upon her goal," X admitted. He glanced at Yuki for a moment, seeming to take the moment to survey her. She didn't want to even imagine what he saw, or what he was thinking. "But, I think might have an idea."

"What is it?" Yuki asked. Anything to figure out this nightmare.

"Exactly what they've said from the beginning. I know something," X said simply. Yuki felt the color drain from her face. That was the last thing they needed to hear.

"What?" Y snapped, turning to face her brother with a harsh glare. "Then why haven't you told us!?"

"Because I don't know what it is I know," X said calmly. Y's face twisted just slightly. Yuki could practically see the way the thoughts raced through her mind, weighing whether to believe him or not. Despite this she said nothing, X took it as an opportunity to continue. "They've been pretty insistent I know something. Part of me thinks they don't know exactly what it is I know either, so they need me to spill. And since they keep dragging up our pasts, they could be trying to hint it's something about the time I spent with Xehanort and just covering their tracks using your pasts as well. But, chances are if it has something to do with Xehanort, I don't remember."

"Did you forget a lot of what happened with Xehanort?" Yuki asked, tilting her head. It had been a long time ago for him. Maybe long enough to forget. But she always thought the memories seemed too fresh whenever he spoke about it.

"Yeah, I tried to anyway," X said with a shrug. Yuki and Y looked at each other, confusion on their faces. "Xehanort left us in the badlands to our own devices most of the time. But, whenever he showed up, well, Vanitas and I would rather forget it."

"What did he do to you?" Y asked, a trace of anger lacing her voice.

"Usually?" X asked, chuckling bitterly. "He called it training. But, that just meant he was going to beat us half to death twice over. He said our suffering would strengthen our darkness. It would make us stronger. And, if we forgot our past, nothing would stop us. He made sure all I could remember was bad. I didn't even remember what anything good felt like." Yuki's stomach twisted into knots at the thought. She knew Xehanort had been terrible to Y and her friends. But to his own students. Uneasiness washed over her, the ache in her heart that had grown familiar growing stronger.

"So if he told you something," she began.

"I probably repressed the memory," X finished for her. "Better to forget than let someone else end up like him. Completely consumed by it."

"Maybe someone is consumed by it," Y said. X nodded in agreement.

"Yeah, I'm starting to think that."

"Let's just find the lights remnant," Yuki said as she shook her head. "We can worry more after we get out of here."

The twins nodded in unison, for the first time in what seemed like forever. Yuki felt her breath calm as she followed after Y, who had taken the lead once again.

She led them around a corner, to dip in the ground. At the bottom of the dip was a wall of some kind made from broken stone. A mural covered the wall, images of some kind of giant figures over the city. Words were written in the strange language, Yuki couldn't make heads or tails of it.

At the bottom of the mural was a small glowing blue crystal. Y bent down picking up the crystal, it hung from a strap of leather. Y looked from the crystal to the mural. Yuki followed her gaze, looking again at the mural.

"What's this?" Yuki asked.

"It looks like a story," X said, taking a step forward and scanning the mural. His hand touched the symbols that made up the writing as he strained to see higher points.

"What does it say?" Y asked. She lowered the crystal to her side, focusing her attention on to X.

"I, feel like I know this story," X said. Yuki tilted her head to the side in confusion. "The people of Atlantis knew a great power. Using this power they built their civilization. It advanced more quickly than any other nation around them. They became myths. But, one day the power turned against them. And destroyed the entire city."

"What about that story is familiar?" Yuki asked.

"The keyblade war." It wasn't X who answered, but Y. Yuki and X both turned to look at her as she crossed her arms. "First Scala, now the war."

"Both things that will lead us back to Xehanort," X said, a hand going to his hip.

"So that's their game," Yuki said. She sighed heavily. This was purposely pushing them to their limits. She was sure neither X nor Y wanted to think about this Xehanort. And even she couldn't say she enjoyed the Xehanort she could vaguely remember. "Well, we can't do anything about that. X, the heart."

"Yeah," X said. Despite that he stared at the mural for a moment. Yuki couldn't read his expression, though she wasn't sure she wanted to. He shook his head after a moment, snapping himself from whatever his thoughts were."Sorry, let's go."

X led them through the ruins easily. This time he wasn't allowing himself to be distracted by the writing on the walls, though it seemed a few times his eyes wandered before he snapped them forward again. Heartless attacks were few and far between as they got deeper in the ruins. It was unnerving. 

They found themselves in what Yuki could only describe as a throne room. An extravagant chair sat slightly raised, looking down at them on a strange pattern of stone. X stopped at the top of the steps that led to the throne, turning to look down at the stone steps.

"Something up?" Yuki asked, as she stood on the step below X.

"They found out how to harness the heart of their own world," he said. For once he seemed to be completely in shock. "That was the power they found."

"That's possible?" Y asked.

"Anything's possible where people are involved," X said, glancing to his sister. "But that doesn't mean it should be done. It's underneath our feet." He nodded towards the ground, but there was nothing that Yuki could see.

"How do we get there?" Y asked, her head tilting to the side as she shared in Yuki's confusion.

"You have keyblades don't you?" X asked, rolling his eyes.

"Oh," Y said, summoning her key.

"Right," Yuki said. "They do that."

Y opened the path with a beam of light. Descending down the tunnel they were greeted with a faint blue glow, much like the crystal Y had found. The end of the tunnel left them at the edge of a shallow pool of water, the heart resting in its center.

Without a word Y handed the crystal necklace to Yuki. She smiled weakly as she took it, taking the first steps towards the heart.

The moment her foot touched the water the entire cavern shook. Yuki stepped back, just as something large and blue scaled flew past her. A giant dragon like creature with tentacles trailing off around its face. Around its head were frills of some kind, shaking with every little sound. A blue heartless emblem outlined in back rested on it's chest.

Yuki cursed under her breath, they should have known something would stop them. Though Myruai's Leviathan was not what she wanted to deal with.

Fighting the Leviathan was as difficult as it would have been to fight a serious Myruai. Every little sound tipped it off to their next move. And every sound it made was enough to knock them down. It was only when X began to make excessive noise echo around the cavern were they able to defeat the Heartless.

As the Heartless fell, Yuki once again approached the worlds heart. She placed the necklace from Y on a small ledge in the crystal itself. Raising her keyblade she watched as the golden chains wrapped around the heart.

In a flash of light the world returned to the realm of light. Leaving them with only the strange visions of the world past. A destructive force from the heart itself. The strange group that had found their way to the underwater city. All to protect the city from its own power.