As the world was slowly pieced together along their trail, Yuki could only look around in confusion. There were the remains of vehicles Yuki had only seen in history books, in tales of wars of a completely different kind. She had never seen them in person, and she had never thought much of it. But the huge metal tanks were strewn about as they came to a courtyard in front of a large building. In the center of the courtyard was where the most damage had been done. And Yuki could only guess it hadn't been from the weapons of destruction around her.

A giant hole took up at least half of the courtyard. Yuki didn't dare get close to the edge, the thought making her knees weak. X had no such qualms and stood right at the edge looking down. He leaned out a little, his eyes squinting. Yuki could only guess that meant he couldn't see the bottom. From as close as she would let herself get she could only see darkness.

She shifted her attention away from the hole and to the rest of the courtyard. There were areas that looked blown apart and even more weapons. The bricks seemed to barely be held together in some places. 

"This looks like a war zone," Yuki said, glancing at Y. She stood away from X, staring at the building that overlooked them. It seemed to be the least damaged of all the area around them. But even then, it had scuffs and breaks in the walls.

"Yeah," Y agreed.

"Back to the unfamiliar again. I'm pretty sure none of us have been here," X said as he stepped away from the ledge, coming to stand beside Yuki. Y turned her attention from the building and on to X with a glare.

"And why is that?" she asked, her voice cold.

"I have my reasons," X said with a shrug. "And they're ones you wouldn't like. So let's not start a fight. Don't have the time."

"Whatever." Y huffed and rolled her eyes. "The lights remnant is in the building."

"Then lead the way," X said, a smirk crossing his face. Yuki held in her confused questions as Y growled.

"Bite me," she snapped. With a sharp turn she stalked away from Yuki and X towards the building. Yuki turned to X, watching as his smirk faded. He sighed and followed Y.

Yuki tilted her head to the side, her thoughts racing. X had gone from taunting to solemn in seconds. Why? What did he have to gain from antagonizing Y further? She didn't get the chance to think much longer. She pulled herself from thought to catch up to the twins who were already making their way into the building.

Despite the building being expansive, Y led them through in a straight shot. The room they found was a large and open office of sorts. Surprisingly the room itself seemed untouched, almost to the point dust was collecting on the desk. Y didn't hesitate to pick up a small metal object off the desk, popping it open with the press of a button.

"Don't forget, 3 October 11."

"A date?" Yuki said, her head tilting. If it had been almost anything but she wouldn't have been surprised. A picture or a time. It looked as though it was a pocket watch, now that she was closer.

"Clearly," X drawled. Yuki shot him a glare, though she didn't remark. He only rolled his eyes. "We have it. Now it's my turn."

"What's the hurry?" Y asked.

"Oh, I don't know," X said, starting what could only cause trouble. "Maybe it's Xehanort going after my friend that I'm a little worried about. I would think you could sympathize."

"Excuse me?" Y snapped. 

"Enough. Both of you," Yuki said, the force behind her words enough to leave an echo. They both fell silent, eyes on her. "I get you're both on edge. And I know X isn't telling us things. And Y now has something she's hiding I'm sure. But this hostility is not going to get us through here any faster. So both of you stop arguing or shut up."

"Fine." Y agreed, looking away. Yuki let out a sigh and turned back to X.

"Come on," he said.

At first Yuki wasn't sure where to follow him. He crossed the room to the window, looking over the courtyard area for a moment. He frowned seeming to consider before he walked back to the desk and pressed in a wooden panel. On the wall beside him a door open, leading to a set of stairs.

"Under a city again?" Yuki asked.

"So it seems," X agreed.

He led the way down the stairs into a strange set of tunnels. Or at least Yuki could only assume they were tunnels. Their path was relatively straightforward, with only a few places they could turn and go in different directions. All around them were pipes of some kind. Yuki wasn't sure she wanted to know what was in them. The thought was enough to send a shudder through her frame.

X stopped, his eyes scanning around them.

"What's up?" Yuki asked, stopping to look at X.

"This place, feels off," X began, biting his lower lip. "I can't pinpoint the heart, exactly." 

"You have got to be kidding," Y said, a hand on her hip as she glared. X returned the glare coldly.

"It's some kind of interference, probably from these pipelines," X continued, looking away from Y. His glare faded as he looked at the strange pipes. Y frowned looking at them once again.

Y"Strange. What could cause such an interference?" she asked. X's frown deepened, if it was at all possible for him to do so.

"Nothing good," he said. Yuki nodded in agreement. "To obscure the heart of a world, I'm not sure I want to know what's in these pipes."

"So what's our next move?" Y asked, drawing attention back on to her. She held the silver pocket watch tightly in her hand, close to her heart.

"We need to get away from these pipes," X said simply. "At least so I'm not surrounded by them. I had a pretty clear idea from that hole outside, but I assume neither of you would enjoy a jump from that height." Yuki nodded without hesitation.

"We can split up again," Yuki said. She turned to Y before she received any acknowledgment from X. "Y, this time you're on your own, sound good?"

For a moment Y stared blankly. Slowly her gaze drifted from Yuki to X and then back again.

"Sure, we'll meet up asap," she agreed.

"Wait--" X began.

"Good," Yuki said, interrupting him before he could finish. Y smiled and walked off, in the opposite direction they had been going. Yuki assumed she would explore some of the other turn-off options.

Yuki turned to X only to be met with a cold glare.

"You're not subtle," X said, crossing his arms.

"Never said I was trying to be," Yuki said. She gave a shrug beginning to walk down the path away from Y. She waited until she heard the sound of X's footsteps behind her to continue. "I had a question, and I'm assuming it's something you don't want Y to know."

"What?" X asked, his voice laced with annoyance. Yuki was almost sure he was going to snap at her any second. The same way he had when she had first started asking the questions he didn't want her to.

"The keyblade graveyard," Yuki began. "Everything Xehanort said. What did it mean?"

"Nothing." X's answer was quick. He hadn't even bothered to put thought into it.

"I expect better lies than that from you," Yuki said. She forwned, glancing over her shoulder to find where X was behind her. X wasn't looking at her, his eyes instead combing over the pipelines beside them. He reached out and pushed on one. It was surprisingly flexible, easily giving way to the light touch X had given it.

"Why bother lying when you know it's a lie," X said. "Too much energy to achieve the same result."

"Why won't you tell Y? Can I know that?" Yuki asked. X considered that for a moment.

"She doesn't need to know."

"Says who?" Yuki asked. It seemed an odd thing to not need to know. It had chased Y for years. Even led to her losing her heart. Had turned X against her. Why shouldn't she know what she was up against?

"She did," X answered, hesitation clear as his eyes darted around the tunnel.

"Huh?" Yuki stopped in her tracks, staring at X as he shifted. He wouldn't look her in the eye as he came to a stop. His hands were clenched, gripping tightly onto nothing.

"I remember many things that my sister has forgotten," X said, his words slowly forming. Almost as if he had to force himself to talk. Like it was tearing its way from his mind. "She didn't want to remember. I don't want to be the one to make her remember."

"Oh," Yuki said. She shifted again as she glanced around. It seemed odd. How long had Y been forgetting? If that was even the truth. Her eyes again went to X. He hadn't moved. "Can I try one more question?"

"You will anyway," X said, offering her a sly smile.

"Tenebris and Lucerna?" Yuki asked. X's smile dropped to a look of surprise.

"Oh," he said. "Those were our names. Our mother picked them out."

"Then, why did they change to X and Y, of all things," Yuki asked. She had always found the names strange. And no matter who she asked they could never explain it. X and Y had practically made it part of their introductions to claim they found it as strange as anyone around them.

"Our parents died when we were babies," X said easily. Yuki had to hold back the gasp. "Twins are bad luck where we're from. So we got passed around among people pretty much all our young lives. They gave us placeholder names, until we would be actually adopted. But that time never came, so X and Y it was. I only found out our real names through some digging. And told Xehanort because I was an idiot who trusted him." Yuki nodded, though she wasn't really sure she followed. She wasn't one to know much about parents. She had been adopted quickly when she arrived on Destiny Islands. And before that, well it hadn't been her. And Kairi couldn't say much about her and Kiu's parents. Only barely did she remember her grandmother.

"I see," Yuki said. She shook her head, trying to clear the excess thoughts. "Wouldn't it be easier to explain all this to Y?"

"No," X said. He looked at Yuki, making eye contact for the first time since they had begun the conversation. Yuki was surprised to see his eyes were red, as if he was fighting back his tears. "It's better she keeps forgetting."

"Any reason?" Yuki asked.

"It's one you don't want to see." X turned away, giving Yuki no chance to argue.

She couldn't think of what that was supposed to mean. Y had always been exceptionally calm and happy. Though recently she had been seeming angrier. But what was remembering these things supposed to do to her? There was a pit in Yuki's stomach the longer she thought about it. Almost as if she knew X was right, though she couldn't place why.

"Hey!" Y's voice cut through Yuki's thoughts. "I found something."

Y appeared from the darkness of the tunnel, a hand on her hip as she looked between Yuki and X. Yuki forced a smile and nodded as X turned, seeming to be waiting for Y to move again. Y turned and walked back the way she had come from, Yuki and X following her in silence. After a few turns through the tunnels, they came to a stop in front of a large doorway.

The door was cracked open, leading to another set of tunnels, this time with no pipes around them. There was something carved on the door, but Yuki couldn't tell what it was with the doors opened. The most she could make out was a symbol that looked like the sun, and a series of other circles with strange writing.

"You good from here?" Y asked, hand on her hip as she looked to X.

"Yeah," he agreed. His eyes scanned the door, taking steps between them to be able to see the whole picture. He paused for a moment. Before he could be hurried he shook his head and passed through the doors.

The tunnels here were easier to follow. At least with X following his draw to the heart of the world. He didn't hesitate at the turns and soon they found themselves in an open room, seeming to be under the hole through the courtyard.

Yuki could only call the room a throne room. The pipes from before all seemed to push their way into the room, finding their end at the back of a single chair.

Sitting in that chair was Zaya. The blonde heartless smiled softly as they approached, her hands braced on either side of her. 

"Hello," she greeted, smiling as her blonde curls bounced. "Glad you three made it."

"Same as the last?" Y asked, drawing her keyblade. X mirrored the move, drawing his own daggers.

"Ah, so you did get to meet Myruai," Zaya said, her smile dropping as her eyes fell to the ground. "I'll have to assume you defeated her then. A shame. She was really the sweetest of us."

"She's better off now," X said.

"Probably," Zaya said with a shrug. "But, I'd rather not have to experience that pain again. If you'd like I could send you straight to castle Impia. No fight necessary."

"I think we'll pass," Yuki said, drawing her keys to stand beside the twins. "There are way too many of you left. We'd stand no chance."

"Fair enough," Zaya said with a nod as she got to her feet. She held out her hand, calling her gunblade to her hand. Yuki frowned as she stared at the weapon. It had been among the first she had become familiar with. Zaya had taught her magic. "Shall we begin then?"

"Actually, I want to ask something," Y said, stopping the others from moving. Zaya tilted her head to the side, unprepared for a question now. "Why these worlds. Worlds that mean nothing to us?"

"They were the easiest to get to," Zaya answered, almost too easily for how unprepared she had been for Y to ask. "We couldn't act within in the inner ring of worlds. Master Yen Sid would have caught on much sooner. So we instead chose outer ring worlds."

"Outer ring?" Y echoed. Zaya chuckled.

"Worlds farther from the epicenter," she explained. Yuki wasn't sure what that was supposed to mean but Y seemed to accept that as an explanation. "They tend to be younger some don't even have their rules created. This one did though, it was beautiful."

"Can you get to the point?" X asked, flipping his daggers in hand.

"Actually, that gives me a great idea," Zaya said, perking up as she looked at the three in front of her. "The founding rule of this world, equivalent exchange!"

"What are we exchanging?" Y asked. Yuki almost thought she had looked at X, as if offering him up for whatever the exchange would be.

"In this world, it applies to their science," Zaya said. She took a moment to consider, Yuki supposed trying to decide exactly what she wanted from them. "But I think we can apply it to our conversation. Would you like an exchange of information?"

"What do you want to know?" Y's answer was instantaneous. Yuki had to do a double-take to look at Y. X frowned, looking between Y and Zaya.

"Oh, Aryum was right," Zaya said, giving another one of her chuckles as glares crossed the trio's faces at the mention of Aryum. "You were going to take up that offer awful quickly. I don't really want to know anything. How about this, you win and I'll tell you something."

Y moved before Yuki could process what was going on. Fortunately, or perhaps, unfortunately, Zaya was able to stop Y with a single move, her gun blade blocking the golden key. Yuki took advantage of her distraction with Y, and X acted on the same movement.

X was the first to land a true hit on Zaya, knocking her back and away from Y. Yuki swung next, hitting with one key while the other blocked her gunblade.

They traded blows, the three trading off their strikes, easily bringing Zaya down, attacking before she had the chance to use the magic she was known for.

X pinned her to the ground with a foot on her chest and a dagger pointed at her throat. Yuki had to look away as the black smoke trailed off of her hands and arms. Sure signs she was fading.

"Alright, what do you have to tell?" X asked. Y stood close by, her eyes so focused on Zaya Yuki wasn't sure she was really seeing anything.

"There were some in this world we were fascinated with," Zaya explained, her voice shaky as she stared into X's eyes. "Called the homunculus, artificial humans."

"What?" Y asked as Yuki gasped.

"They were a conglomeration of thousands of souls," Zaya went on, not acknowledging the shock, if she had even noticed. "Or as we would know them, hearts. You and your brother, you're not so different. Perhaps the queen too."

Yuki looked up only to watch Zaya fade, the crystalline heart floating up into the darkness above them. She could only hope she hadn't lost all her color. What did they really know?

"What the hell?" Y asked.

"I- I don't know," X said, his brow drawn tight in his confusion. He hadn't looked away from where Zaya had been moments before.

"You better not be lying," Y hissed. X was silent for a moment, only staring at the ground. He looked up and around them, focus seeming to land on the pipelines that had previously seemed so ominous. Now Yuki was even more afraid of them. If this world had made artificial humans, she didn't want to know what else their world did. 

"I'm not sure. That's ridiculous," X said. Yuki almost found herself nodding in agreement, buts stopped. She wasn't exactly one heart anymore, was she?

"I think I might know," she muttered, her hand resting over her heart. The unease she had learned to associate with Vanitas shifted and rolled, filling her body with unrest.

"What?" Y asked. Yuki jumped a little, looking at Y in an almost panic.

"Um, nothing. I'm not sure it's what she meant anyway," Yuki said quickly, her mind racing. She needed an answer at least enough to satisfy Y. "But, you know what Mr. H say, we gotta meet people to expand our world. So, that kinda makes us a bit of everyone our hearts have ever met right? They're all connected."

Y frowned, holding out the pocket watch to Yuki.

"Maybe."

Yuki sighed in relief as she looked down at the watch, her eyes glancing over the strange seal on the front of it. She pushed away the feeling of anger and resentment as she set the watch on the throne-like chair Zaya had sat in. She held up her key, letting the gold chains envelop the chair and watch.

The memories of the world flashed before their eyes, so much Yuki could hardly keep track. Always at the center of it were people marked with a snake biting its own tail. At the death of thousands, and battle after battle. As the world returned to the light Yuki could only see fire.

As the fire faded from Yuki's eyes they were left again on the path through the darkness. Y said nothing as she took the lead. Yuki sighed, looking down. The unease had faded and was left only with bitterness.

"And I'm the liar," X said as he passed Yuki. She couldn't even bring herself to argue, as she watched him follow Y like a shadow.