It had been the dead of night when he heard the words resonate in his heart, and he had set out immediately without a second thought. It wasn't as though he knew where he was going or how to get there, but the echoes of a secret promise led Riku beyond the realm of the worlds he had traversed to a place he had never been without explanation. What had Master Yen Sid said?

May your heart be your guiding key.

Or, perhaps he just wanted to prove himself. A test, like the Mark of Mastery. The longest test he had ever taken, one he barely remembered starting when he was only a child.

But time was a funny thing, and he was no longer a child as he stood resolutely in the grand marble hall centered within Castle Oblivion – no. The place was hardly recognizable anymore.

The Land of Departure.

The man standing across for him had not aged a day since Riku had seen him last, however, all those years ago. A remnant of the briefest, barely-formed memories, and yet as Riku stood before the mentor he had never had, a look of understanding passed between them, as though they had known each other the whole time.

"Well," Terra uttered. "Look at you."

"Thanks," Riku said, the barest of smiles passing over his face. "I finally fulfilled my promise to you."

Terra nodded softly. "You did. Now there's nothing left for me to teach you. You're a true keyblade master...not to mention a great leader to those around you. You've even found the strength to save your friends."

The familiar words jogged Riku's distant memory, the sentiment echoing faintly through his head – one he had held on to for most of his life, without even realizing it.

Strength to protect what matters.

But then...

"It's not enough," Riku said simply.

He hadn't been able to save Kairi – Sora had. And now...Sora was gone. Riku hadn't saved him either. At least, not yet.

Unexpectedly, he was drawn from his thoughts by a pair of large hands coming down on his shoulders as Terra crossed toward him...and to his surprise, Riku realized that he was almost as tall as Terra by now. In his memory, he was always gazing upward at the towering stranger who had come to his island so long ago...

"The very fact that you were able to make your way here proves just how strong you are," Terra explained, gripping Riku's shoulders reassuringly. "That's why I called for you."

In the midst of his ruminations, Riku faltered suddenly.

...What?

It took him a moment to process the words, but once he had, he was just as perplexed. In the back of his mind, he felt suddenly foolish for setting out the way he had, blindly and with such urgency, racing through the Lanes Between without even knowing why...and for what? All because in the dead of the darkest night, he had heard the still, small voice that had stayed with him for so long call out to his heart from a distant land.

But then...what kind of mentor would pull something like that, anyway?

There was a blank silence.

"...That's the reason?" Riku blurted out, and he saw a smile tug at the corners of Terra's mouth at the incredulity in his voice.

"You expected more?" he mused.

Riku stared at him.

"Well...yes," he said blankly.

Terra stared back at him for a few moments, just as the massive marble doors at the far end of the vast chamber in which they stood yawned slowly open before the only other two residents left within the Land of Departure. A look of surprise passed over both Aqua and Ven's faces as they entered in time to find both Terra and Riku burst into laughter, the sound echoing merrily off the high ceilings above them and bouncing from the walls. A wide grin spread immediately over Ven's face as the sound, and he was the first to come bounding up to the pair of them.

"Hey you two...what's so funny?!" he said eagerly, his eyes alight as he gazed up at Terra.

Terra chuckled a little and folded his arms wryly.

"It's a secret," he mused, turning on his heel away from Ven and striding idly off toward the sprawling steps that led up to the masters' observatory at the head of the room.

"What?!"

Riku chuckled again as Ven bounded after Terra in indignation, then glanced over as he felt Aqua pause at his side.

She wasn't looking at him, however...her gaze was straight ahead, watching Ven chase Terra up the marble steps before them. Riku studied her profile for a moment, but couldn't get a read on her, and she didn't say anything to him, either. Maybe it was the task ahead of them, he reasoned, that had her lost in her thoughts.

"...Are you sure about this?" he prompted finally, and after a pause, Aqua finally tore her eyes away from her two friends to look over at him.

"Yes," she said firmly, meeting his gaze. "But don't worry. I'm not alone this time."

She offered him a slight smile, and Riku's eyes followed her as she walked forward to join Terra and Ven...he wondered what it was like for them, to be back together after so long.

I hope...it doesn't take us that long to find Sora. He paused, then shook his head at his own ruminations. Yeah right. He'll be late about it, but he'll show up in the end like usual. And with all these people looking for him...

Pulled from his thoughts, he squinted against the brilliant flash of light that illuminated the great hall, gazing on in awe as the mystical armor he had heard so much about donned the forms of the keyblade trio before him.

It was as Aqua and Ven were disappearing inside the deep, swirling portal they had conjured to the Realm of Darkness that Riku saw Terra pause, and turn briefly to face him. Even with his features obscured by the familiar helmet of the lingering specter that Riku had stood before briefly before their final battle with Master Xehanort, he could feel Terra's gaze burning into him, and he stared back unflinchingly.

Take care. He didn't say it, but somehow, he knew Terra understood, and after a moment, he was watching his lost mentor's back again as he was swallowed up by the surrounding portal.

It had been a year since Riku had set foot on the sprawling marble floors inside the castle, and the Land of Departure had changed in his absence. Empty and devoid of any occupants, the light and life of the ornate halls seemed to have dimmed, and as he stood before the three empty chairs overlooking that same chamber in which he had said goodbye to its new rulers, he could see particles of dust drifting lazily through the light streaming in from high-arching windows.

Riku waited patiently, a slight but expectant smile on his face, though it wasn't immediately clear what he was waiting for. Even so, it wasn't long before a pinprick of light caught his eye at the top of the marble steps, and he stirred a little at the sight of it. Slowly, it began to grow and expand outwards, and the scent of darkness that he had become so familiar with began prevalent in the room as the portal yawned open.

Ven bounded through first, his armor clattering loudly throughout the still, silent hall. In his wake, Aqua followed, stepping out more gracefully and then turning to look over her shoulder as Terra brought up the rear, seeing the other two out as he exited the portal, which pulsated and closed up a few moments later behind him.

"Riku!" Aqua called to him, as Ven waved.

"Hey," Riku greeted as the three armored figures descended the sprawling steps before him, closing one eye for a moment as a brilliant shine filled the room.

As it cleared a moment or so later, he could see Ven's unmasked face beaming at him as he approached, still waving enthusiastically...Aqua's gaze was warm as she fixed it on him, and behind her, Terra offered him a swift nod, their eyes meeting for just a moment.

"Good to have you back," Riku said to them, setting a hand on his hip. "Did everything go okay?"

"Yes." Aqua banished her keyblade, and Terra and Ven followed suit as they came up to Riku – despite the time that had passed, Riku noted, Ven hadn't grown at all; but time, he knew, passed differently in the Realm of Darkness, if at all. "Although..."

"What is it?"

Aqua sighed, and lowered her head a little as she glanced away. "I'm sorry, Riku. There was no sign of Sora."

Riku looked unperturbed, however, and he tossed her a reassuring smile. "Hey, don't worry about it. It was worth a shot, right? Besides, we have some leads on our end."

"Really? That's good," Aqua breathed, sounding relieved.

"Actually," Riku continued, as Terra and Ven continued past him toward the end of the great hall, "that's kind of why I'm here. Terra."

"...Hm?"

Terra paused, turning to look back over his shoulder toward Riku, his expression guarded but not unkind. Undeterred, Riku turned full to face him, setting his hand back on his hip.

"I have a favor to ask."

He had talked to Yen Sid already, and even King Mickey. Kairi, after all, would be training under Aqua before long, and to Riku it was only natural that he follow suit before he set out on a new journey into the greater unknown to get Sora back. That kind of adventure needed more than just the strength to protect what mattered, and in Riku's mind, there was only one person who could help him with that.

"Yen Sid has sensed something in the land with no time," Riku elaborated. "He wants you to go and investigate it, and...I want to go with you. As your apprentice."

Terra often said more with his expressions than his words, in Riku's opinion. At the request, he turned more fully around with a look of perplexed incredulity on his face, which would have been comical under less dire circumstances.

"What?" Terra shook his head a little, then smiled softly. "...Between the two of us, you know which one is the Master, right?"

Riku set his hand on his hip. "You may be missing the title, not the skill...Yen Sid said so. Besides...I'm a self-trained keyblade master. I know how to fight, but a lot of the knowledge passed down from generations of keyblade wielders has never been taught to me."

Terra watched him in mild surprise, but Riku held his gaze...stubbornness had always been his strong suit, for better or for worse, and Terra was going to have do so a whole lot more than look at him to change his mind.

"There's something I have to do to save Sora," he went on. "To do it, I have to go somewhere I've never been before – somewhere none of us have ever been before. There's no telling what I'll find there, and if I have to save Sora, I'm gonna need all the help I can get. I want you to teach me, Terra."

Terra was quiet for a few moments, but then turned away again.

"Sorry. It's like I said before...I have nothing left to teach you."

Riku took a step forward after him, taken aback by the finality in his tone so soon. "Hey – wait! What about what Yen Sid –,"

"I'll head out tomorrow to take a look," Terra said gently without turning around, starting toward the exit at the end of the long hall with Riku hot on his heels as he strode away. "Aqua's training with your friend Kairi will start soon. Maybe you can –,"

"Terra." Aqua looked up, and he paused at the sound of her voice. "I think you should take Riku with you."

Terra paused, glancing back at her in surprise.

"You too?" he asked quietly in exasperation, and Aqua smiled, nodding as she came up behind Riku and set a hand on his shoulder.

"Sounds like a great idea to me," she said cheerfully.

"But –,"

"Come on," Riku insisted.

Terra regarded the two of them for a moment, and then sighed audibly, his shoulders slumping a little.

"...Fine," he amended finally, turning away once more. "If that's what you want. Riku...will you be ready to leave in the morning?"

"You bet."

"Hey – I wanna go too!" Ven interjected, running to Terra's side to peer up at him, hands clenched enthusiastically. "I'm not a keyblade master yet either...let me come with, Terra!"

"No, Ven." Terra shook his head. "We don't know what we're dealing with yet. You stay here with Aqua."

"Aw, come on!"

"You're too young!"

"Am not!"

Riku looked on in mild amusement as Terra slung an arm around Ven's shoulders to ruffle his hair as they started to make their way out of the grand hall again, wrestling him easily into a headlock.

Aqua stepped forward to stand at Riku's side, following his gaze as Ven's laughter ricocheted off the polished marble, and after a moment, he looked over at her.

"Thanks," he said, and she offered a slight smile.

"Of course." She shook her head a little. "Maybe I'm the one who should be thanking you."

"Why'd you convince him to go along with it, anyway?"

Aqua lowered her head then, silent for a few moments before she lifted her eyes to Terra's back as he wrestled with Ven in the distance.

"I..."

"What?"

Aqua shook her head. "I thought...it might be a good idea for you two to spend more time together. That's all."

Riku did a slight double-take.

"You did?" he asked, surprised. "Why?"

Aqua wasn't usually this hesitant to have a conversation, he thought...maybe she had been hanging around Terra too much in the Realm of Darkness.

"...Well...it's...about when you came to visit us before..."

Something in her tone caught Riku's attention then, and he looked over at her. Aqua sighed, still gazing straight ahead.

"It's just..." she uttered softly. "That day? That's the first time I've heard Terra laugh since we left home ten years ago."