A/N: No, don't adjust your browser. The changes that you'll start to see happen to the 'Time elapsed' lines are deliberate, and the reasoning will become clear in time.
Also, Sora's keychain. It's kind of a replacement for the Gears system that appears in Days, however I've made a change. The form his keyblade takes with it depends on Sora's thoughts and certain other requirements. For example, the form it took - Sign of Innocence - is because he was curious. I'll leave you to guess the rest as they appear though.
Enough from me. Enjoy.

Day V
The World that Never Was
Time outside elapsed: 01:?

"You'd betray... king?"
"Not on your life! But I'm... either, 'cause he's... through together! See... Donald! Could ya tell... sorry?"
"Hold on, Goofy! We'll... together! Well... you know... one for all."
"I guess... stuck with us..."
"Thanks a lot... Donald, Goofy."
"How will you fight without a weapon?"
He looked up in defiance and woke up with a start.
That boy. He'd been dreaming about that boy he'd seen. Taken from his point of view. Fragments of a conversation, not clear enough to make out. Who were Donald and Goofy?
Sora shook himself, telling himself it was just a dream, and pushed aside a bit of wall that had actually turned out to be a door to a shower. He'd only discovered it by accident. No one had told him it was there.
His thoughts strayed back to the dream as he showered. It was still clear in his mind, but the dream itself hadn't been clear at all. There was a room, a large round room. A fountain, stairs going up to a raised area with pillars supporting an upper balcony. There'd been another boy there, a white-haired boy in some kind of suit of blues and reds. There'd been an emblem on his chest, very similar to the one the Heartless had. And a keyblade. He was certain of that. His keyblade, in it's normal form, was in the boy's hand. Why did he have it?
He'd entered the room and seen the boy alongside two... two... he couldn't remember them anymore. One of them had protected him from an attack from this boy. Why?
It had made the boy say something about betraying and a king... the rest hadn't made any sense. It faded in and out too much to understand.
Donald and Goofy. He remembered the names, they were strangely familiar – but who were they?
Sora dried himself off absently, trying to see any sense in this dream.
Someone knocked at his door as he pulled on the coat again.
"Come on in," he called absently, taking a towel to his hair again after it dripped a few times.
"You're up late today," Zexion noted, letting himself in. "Saïx asked me to find out where you'd got to."
"I guess I slept in a bit later than I meant to," he admitted ruefully. "I was having a bit of a bad night."
"A nightmare?"
"What's that?"
"Another name for a bad dream."
"I guess you could call it that." Sora hesitated, then asked, "Could I... tell you about something I keep seeing?"
"Of course. What's troubling you?"
"On my first day, when Axel was guiding me around Twilight Town, there was this mirror. When I looked in, for a few moments I'm fairly sure it showed someone else. Then yesterday, at the waterfall I had to investigate it happened again – but the reflection stayed. At least until I looked away, when I looked back it showed me again."
"What did you see?"
"He... looked like me, but different... lighter hair, different clothes. I think he must have had a Heart too, whoever he is. Then last night, I was dreaming about him."
"Curious. Could you perhaps go into more detail for me Sora?"
Sora nodded, describing the boy first then recounting what he still remembered of the strange dream.
"I guess I must sound real weird, huh?" he asked when he finished.
"Certainly this is unusual, but I think we can rule out coincidence. I think I'll ask Saïx to cancel your mission for today. I'd like you to have Vexen examine you."
"Do I really have to put up with him again?"
"If he troubles you, I could take care of it. In return though, I want you to join me on my own mission afterwards."
"That sounds fair."
"Then wait here for me. I will speak with Saïx first to make the arrangements."
Zexion's examination of him seemed remarkably lacking in actual examination, instead consisting more of various blueish waves of light flowing from his hand to around him. He continually examined the ever present lexicon he carried, returning to it after every wave.
"I believe you have little reason to be concerned," he said at last. "It seems to be your memories trying to resurface."
"What's been stopping them?"
"I can't tell that just yet. If you have any further episodes such as that dream, let me know."
"What if I keep on seeing him appear in my reflection?"
"Don't be too concerned about that. You're otherwise perfectly fine Sora. Is there anything you have to do?"
"I don't think so."
"Then we'll depart for my mission. Understand that you must keep your hood raised for this mission, and there's not to be a single word spoken out of turn."
"So, hood up, shut up?" he asked, starting to pull it over his head.
"Essentially," Zexion answered, following suit.
"Where will we be going?"
"To a place called Destiny Islands. Our task there is to observe only – regardless of what we see. Do you have questions to ask before we leave?"
Sora shook his head, though it may have been hard to tell with the hood up, but Zexion seemed to get the idea.
The dark corridor exited onto a wooden deck, for a moment making him think they were aboard a ship, but it just seemed to be a construct made between two rock pillars. Ahead of them stretched a long beach, at the near end a small pier, and at the far end a bridge that lead out to a squat, flat rock with many palm trees around. A short way inland, tree houses seemed to have been built around the trees, along with a collection of ladders and walkways to reach them.
Off in the distance to one side was another island with a village on the shore, but it was strangely deserted.
The entire place had an air of familiarity about it. He was certain he'd heard the sound of the waves on the beach before, but how could he have? He'd never been here before.
In a short burst of darkness, a figure appeared on the squat rock. He looked identical to the boy in his dream, the one with the Heartless emblem on his chest. Despite Zexion's warning, a surprised gasp escaped him when he recognised him.
He'd told Zexion about the boy, so he must have realized too. A hand reached to his shoulder warningly, but nothing was said. Sora nodded to him in silent acknowledgement, then returned to watching the scene.
A greenish light appeared on the beach, depositing three figures. One looked like a duck, the second tall dog that seemed to have a kind of permanently cheerful disposition. Donald and Goofy. The third...
"That's him," he murmured to Zexion as quietly as he could. "The boy."
"So I see." Zexion answered. "Hush now." He made a gesture with one hand, and the voices of the trio came to them as clearly as if they were stood right beside them.
"Is this... is this my island?" the boy asked, half to himself.
"Maybe we should look around?" Goofy suggested.
Instead of replying, the boy spotted the other one on the rock and called out, "Riku!" scrambling up a small hut to reach the bridge that lead to him.
"Don't bother," Riku replied in a voice that didn't seem to match up with him. "Your voice can no longer reach him where he is. His Heart belongs again to the darkness. Where all things start, and all things end. Hearts are no different to this."
"The Superior?" Zexion murmured to himself. "Impossible..."
Riku's form changed, becoming taller. He resembled Xemnas, but wore a white robe, open at the front to show the same Heartless emblem he'd seen on Riku's chest in the dream.
"We're leaving," he told Sora. "Now."
"But-"
"It's too dangerous for us here," Zexion cut him off, rapidly calling a dark corridor and almost dragging him into it by the hand. Before the view changed to the inside of the corridor, he saw a strange creature appear behind the changed Riku, and a keyblade appear in the hands of the boy – identical to his own in it's normal form.
Then Zexion gave a last tug, pulling him fully into the corridor and quickly through it to the Grey Area.
Saïx glanced over as they emerged. Zexion shook his hood back.
"You're early," Saïx noted.
"You and I need to talk go to Where Nothing Gathers now. He needs to hear about this."
"And him?" Saïx nodded to Sora.
There was a pause before Zexion answered, "Sora is fine. The examination yielded no useful results." He turned then to Sora, who pushed back his own hood and continued, "Remain here in the castle, Sora. If you do have to leave, don't go back to that place." Then to Saïx, "Let's go."
The two vanished into dark corridors, leaving him alone and without any answers.
He'd seen the boy in his reflection. He'd seen all of the people present in his dream. But he still didn't know the boy's name, or why he looked so much like him? Who was he? Why did he have a keyblade just like his own?
His view changed abruptly, forming into the room he'd been in when Axel had taken him to meet everyone. This time though, he was sat on one of the two thrones that had been unoccupied at the time. Almost directly opposite him was Xemnas, with Zexion and Saïx on their thrones, on either side of the circle, about half way between him and Xemnas.
"Sora," Xemnas nodded to him. "Remain away from that world. It would not be safe for you there."
"Why not?"
"The one you saw there who was identified as Riku is a threat to us all, but to you particularly. You are quite important to the Organization – you are the only one who can gather Hearts for us. Your continued well-being is our concern."
Sora nodded, understanding. He couldn't put himself at risk. They needed him. He needed him. Once he had a Heart...
"You should take the rest of the day off," Zexion suggested. "Take an early night."
He nodded again, this time understanding where he was, and used his own dark corridor to return to his room in the castle and take that advice.

He was dreaming again, seeing events from the boy's eyes again. The changed form of Riku hovered in black air before them.
"It is futile," he told them. "The keyblade alone cannot seal the door to darkness." He reached out into the distance toward an immense door and cried out, "Kingdom Hearts! Fill me with the power of darkness!" The door began to open, billowing black smoke. "Supreme darkness..."
"You're wrong," he found himself saying. "I know now, without a doubt. Kingdom Hearts is light!"
A shaft of light beamed through the growing gap in the doors, illuminating the figure before him then destroying it entirely.
They somehow flew toward the rocks around the door, landing on them nearby the great door.
"Come on," he called to Donald and Goofy, pushing against one side of the door. It didn't budge, and neither did the other side when they pushed against it.
Goofy paused in his pushing, seeing something.
"Stop staring and start pushing!" Donald snapped at Goofy, but then looked around the door to see what had stopped Goofy.
"The Heartless!" the two exclaimed together. He glanced around the door himself now, seeing a huge tide of Heartless just waiting to come through the door.
"Hurry!" Donald told them.
"I can't shift it..." he muttered
"Don't give up!" It was the voice of Riku, not the changed one he'd heard on the island, but the one he'd heard in the dream.