Merlin appeared not long after Marluxia's Absent Silhouette had been challenged and defeated. Donald was talking rapidly, trying to fill him in on the situation, but stopped when he realized Merlin had brought them all back to us.
"Perhaps I'd better see for myself instead," he murmured, examining the Cornerstone. After only a few moments to examine it, he added, "Interesting, very interesting."
"Merlin, what's happened to it?" Minnie asked him.
"This is not good. In fact, I'm afraid it's very serious. And there's only one thing to be done about it." He waved on arm, and the silver door to Timeless River appeared nearby.
"Don't worry, Merlin," I said. "I'll keep them out of trouble. I'm sure they'll pay attention to me like they do everywhere else."
"You know where this leads, don't you?"
"And what's going on there, who's to blame, and what we have to do."
"Be very careful there, Sora. The nature of that world-"
"Might tempt us to do something dark, I know. Like I said, I'll keep them out of trouble. And I know better than to meddle there."
"Pay attention to him, all three of you," Merlin warned the others then. "Trust in him especially carefully while in this world."

I like Timeless River. It's nice and uncomplicated, at least for us who can tell the difference between past-Pete and present-Pete. Even most of the local Heartless aren't too much trouble. The main exception are the car-like Heartless – those ones are annoying.
The door from the Disney Castle spat us out, one after the other. Demyx first, then me, Goofy and Donald last of all. I could already tell everything including us was in black and white, and the few sounds there were had the slight difference to them that everything in Timeless River shares.
Naturally, I took on Sora's usual appearance in this world, as did Donald and Goofy their own. Demyx on the other hand remained unchanged except for being totally in black and white.
We got off each other, dusting ourselves off. The Cornerstone as it had once been, unprotected and with it's protective shield unfocused, lay on the top of the hill nearby.
"Hey, look!" Goofy exclaimed. "There's the Cornerstone!"
"Uh... are we meant to be..." Demyx started.
"Yes," I answered. "And the word you're looking for is Deja Vu, Donald."
"You knew, didn't you?" Donald asked me.
I nodded, "I can see a lot more about this place. Merlin was right; trust me and be very careful what you do here."
"What's so special about it?" Goofy asked.
"This world? It's the past of the Disney Castle and town. That's why we have to be careful, if we don't take care, we could alter the future."
"Wouldn't that be good though?" Demyx suggested. "I mean, if we could make it turn out better-"
"Then we wouldn't come here, and therefore wouldn't be able to make those changes."
"But that'd make the changes not happen, so we would come again and-" he broke off and frowned.
"Yeah, I find it's better not to think about it," I said, understanding. "Otherwise you'll just give yourself a headache. Don't get surprised in a moment, by the way. He isn't the Pete we know."
I got a shared look of puzzlement until the past-Pete came running into view.
"Hey, you!" he demanded of us. "Seen any bad guys around here?"
"Not here," I answered. "But he's around someplace. Would you mind some help finding your steamboat?"
"Now how'd you know it was missing, huh?" he asked suspiciously. Maybe I shouldn't have mentioned it.
"I'd... heard about it."
"From who?"
I thought quickly, then answered, "Mickey – your deck hand."
"Huh... I guess he's making himself useful then..." he muttered, then wandered off down to the pier.
"Should we go after him?" Goofy asked me.
"No. We've got no problem with that Pete. We might know what he'll become, but there's no point in punishing him for something he hasn't done yet."
"What about his steamboat?"
"We'll find it along the way. Keep a lookout for a door like the one that brought us here. But first, something else has to happen right here on the hill with the Cornerstone."
As if on cue, the first of the curtained windows appeared not far away, springing out of the ground like a flat comic character springing back to life again.
Demyx glanced behind it, then tugged on the cord beside it. When the curtains opened, we saw the same scene we were beside, but with four different windows. Each of them opened to admit the nearby Heartless, then disappeared. Then right afterwards, the scene showed us being deposited here by Merlin's door, and all that followed up until just before past-Pete showed up.
"What was that about?" Demyx asked, puzzled. "Heartless going out, then us coming in..."
"Look behind us. I'll bet those same four windows have just appeared. We'll have to go through each of them and drive out the Heartless in each of them. Watch out for Mickey too."
"Let me guess," Donald said. "He's not the same one as the King we know."
"Right. We could take one each, but I think we'd better stick together."
I won't go into what happened in al of those areas, except for the last of them – which for me, was the burning building. Along the way we saw each of the visions from the present-Pete's point of view, learning about how his feeling sorry for himself had led to the appearance of the other door to Timeless River.
It was in that area with the building on fire that I had the most trouble with the Heartless, particularly the Hot Rod Heartless. In the midst of that, I had attempted to call on Valour form – except one of those Heartless caught me, and I found myself for the first time in Anti Form.
Donald and Goofy both disappeared, just as when Sora enters that form, but Demyx was around to see the effects.
My original fears that I would become as I had been when a Heartless were unfounded. True, I thought at a much more basic level that lent itself well to the wild, almost feral but swift and deadly attacks that go with the form, but I still thought. There was no overpowering urge to consume the Hearts of others, no change in the way I thought as I used Anti Form's abilities to excess. To say I decimated the Heartless would be to say that I was only a little unkind in my treatment of them. Demyx just looked on, looking more afraid that I'd turn on him. I retained enough thought that I wouldn't do that though.
Once all four doors were cleared of Heartless, we noticed the Cornerstone had been taken while we'd been busy.
"I've got a little job for you," I told Demyx as we headed to the waterway, knowing what we'd find. "The Cornerstone is on a raft behind the steamboat, and our Pete's on top of it. Can you wash Pete ashore, and the Cornerstone back up where it's meant to be?"
"I dunno about the Cornerstone, Sora. But Pete, sure thing. What happens then?"
"We get to beat him up, with the past Pete's help. That'll make him lead us to the door he used to come here, I'll seal that door, we put the Cornerstone back in its place, and then we also go back."
"Does he always make things sound so simple?" he complained to the others.
"Sometimes he doesn't even tell us this much," Donald grumbled.
"Oh, stop that," I told them. "It's not like I've gotten us into anything we couldn't get out of again, right?"
"Doesn't mean you're not going to sooner or later."
With Demyx's help, the past-Pete took his steamboat back right away, while the rest of us chased down the present-Pete until he fled through the same door he'd come by. Despite his changing the scene to try and turn it to his advantage, the fight didn't really challenge us much and so we locked the door he'd used, making it disappear. The past-Pete gave us a hand putting the Cornerstone back in its proper place, and then we headed back through our own door.
Interestingly, Donald did not try to change the past this time, though that may have been because he knew I'd stop him if he tried. Once back, we were congratulated on good work, the thorns gone. Merlin gave me the keychain for the Monochrome Keyblade, though I didn't equip it right now.
Then during Daisy's chase of Donald, I unlocked the next pathway with the restored Cornerstone, calmed Daisy for our borrowing of Donald, then we were on the way again.
I could have gone to either of Atlantica or Port Royal here. Atlantica, though free from Heartless, still did not appeal to me because of the singing, and the story is that fragmented so much that I wanted to leave it until I could get it all done in one go.
So instead, I opened the path through the Floating Island to go to Port Royal. One of the other worlds I'd been looking forward to.
Once the route was opened, I once more turned my attention to the book and managed to finally get fully up to date. A lot had happened since I'd gone to Castle Oblivion – more than I thought. But then, from my perspective, it had seemed like only minutes between the last memory I had of entering Castle Oblivion, and getting woken up by Roxas.
This left me with a series of comments and remarks from Sora – mostly not very complimentary ones. While I'd been sleeping, he had made a few changes to make things more interesting for me in this adventure, though he didn't say what they were. But a lot of them were now altered further by what I'd done, some apparently by Roxas during his time with the Organization and after, and now Sora himself was refusing to intervene any further. He'd give me warnings so long as I paid attention to the book, but that was all.
One of the more common warnings was to be very wary any time one of the deceased members of the Organization showed up. With only Xemnas, Saïx, Luxord and Axel left, and Axel having turned traitor because he wanted to see Roxas again, there was a two in three chance I'd come up against one of the more powerful members. Having Xemnas show up in person would be more than a little inconvenient.
But perhaps the most significant notice he'd left me was about Roxas. Where Roxas had been created from me instead of Sora, he'd inherited much of the knowledge I'd had about his own life, different or not. Though he never showed it, it meant he retained the memories of Xion thanks to that, and even more than that, he had the ability to predict the future – not just know what was going to happen like I did, but to know what would happen even with any further alterations I made. It was limited to here in the worlds I went to and the story events in each of them, but it was an incredibly powerful ability. It had already been seen once, where he'd warned me about Saïx in the Beast's Castle. This was not something to be ignored at any point.