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AN: A couple of details of this story were inspired by the work of Crossoverpairinglover, and are used with permission; hope you like the results.

AN 2: Timeline-wise, this story starts just after the events of "A Diamond in the Rough!" (the episode where Ash and the Kalos gang visited Goodra before heading on to the Kalos League), but then… well, things get complicated for reasons you'll understand later

Temporal War

As he and his Kalos friends stood outside Goodra's new cave, saying their final goodbyes to his old dragon-type before they moved on to the Kalos League, Ash allowed himself a moment to wonder if his new arrangement with Goodra would actually pay off.

He wanted to believe that he could make it, and it wasn't that he didn't have faith in his Kalos team, but after the way things had gone in the Unova League… well, anyone would feel anxious after that kind of loss, right?

It had been over a year since that battle with Cameron, and Ash still couldn't decide if he was more annoyed that he hadn't chosen a better team or that he would have lost even if he'd not had the advantage of having six Pokemon when Cameron only had five.

Granted, he wouldn't have liked winning that way, but at least under those circumstances they might have had a chance to have a rematch with the right number of Pokemon that would have tested both him and Cameron more fairly, unlike when they made mistakes like letting Oshawott get overpowered by Hydregion or Ferrothorn lost to Pignite.

Still, he'd come a long way since the way things had fallen apart in Unova, and with the additional support of Serena, Clemont and Bonnie, Ash had faith that he still had a good chance if he could get through the first few rounds of the Kalos League. Once he had the option of using all six of his Pokemon, he'd have access to a new team that he'd trained to their peak and had proven themselves against all kinds of opponents, as opposed to the more mixed training of his Unova Pokemon…

"Hey!" Bonnie said, looking curiously over at another part of the swamp, her head on one side as Dedenne's ears perked up from her shoulder. "What's that?"

"What's-?" Ash began, before he heard the strange lilting sound that Bonnie must have heard. For a moment he was prepared to put it down as just the sound of another creature native to these wetlands, but that idea was put to the side when he realised that he didn't recognise the noise despite the warden's assurance that they'd seen everything the wetlands had to offer.

It did sound familiar, but it wasn't the kind of familiarity he associated with a recent encounter; that was the sound of something he'd encountered quite a while ago…

Curiosity sparked as he tried to follow the noise back to its source, Ash hurried over to a small cluster of bushes, his mind only partly aware of Serena, Clemont and Gooda close behind him, Pikachu still clutching onto on his shoulder while Bonnie and Dedenne ran alongside him.

He knew that it was probably going to just be a Pokemon that had recently arrived in the wetlands from somewhere else, but there was always the possibility of finding something new, and just because some Pokemon were more familiar than others didn't mean that it wasn't interesting to see another one…

Then he reached the middle of the cluster of bushes and saw exactly what was floating in the middle of the small pool of water at the heart of the bunch, and his eyes widened in shock.

"Celebi?" he said, staring at the small green creature incredulously, mind flashing back to his brief friendship with Sam and the nightmare of fighting Kodai's attempts to harness Celebi's powers for nothing but his own selfish benefit.

"Celebi?" Clemont, Bonnie and Serena repeated with the same degree of incredulity.

"As in the legendary time-travelling Pokemon from Johto?" Clemont continued, looking between the creature and Ash in surprise as Celebi floated over towards them, a curious smile on its face. "And you just… have you seen it before?"

"Once or twice," Ash said, waving awkwardly at Celebi as it waved back at him, leaning him and Pikachu to exchange uncertain smiles. "I mean, I helped protect one from a Pokemon hunter in Johto, and there was this time when some guy in a small town in Sinnoh was trying to use Celebi to help him see the future…"

"You found one in Sinnoh?" Serena looked at Ash in surprise.

"Ah, look at it!" Bonnie said, ignoring Serena's questions while she smiled happily at Celebi as the small green creature floated over to drift around the group, looking at them with a thoughtful smile. "It's so cute!"

"Bonnie, be care-" Clemont began, before Celebi's thoughtful smile changed as it looked upwards, head cocked to one side as though it was listening to something. As Ash strained his ears, he heard a strange ringing sound that sounded vaguely familiar, followed by Celebi flying upwards as it began to glow with a brilliant green light.

"Oh no," Ash said, suddenly remembering Sam's story about how he'd come to the future in the first place. "Everybody, get back-!"

Even as he spoke, Ash knew that his warning was too late, as the wetlands around them suddenly appeared to be visible through a strange blue filter while some kind of golden circle expanded behind Celebi, and then the entire world was filled with a brilliant white glow that seemed to block out everything but his friends, Pikachu, Dedenne and Goodra. For a moment, the four humans and three Pokemon seemed to be floating in nothingness, everything around them warm but blank, nothing visible but white light and the seven of them, but just as Ash thought he caught a glimpse of a flash of green light and some dark figure off in the distance, he only had time to turn his head to try and see it better before the white light vanished, and the group all fell down a few feet to the ground below them.

Looking around, Ash was relieved to see that everyone else was with him and apparently unhurt, but it was easy to see that whatever Celebi had done had moved them somewhere else. Where they had been in the wetlands just a moment ago, they were now on a simple path between trees and open fields, not dense enough to be called a full forest but not quite as open as the wetlands.

"Uh… what just happened?" Serena asked, looking anxiously at Clemont and Ash.

"I… don't know," Ash said at last, looking uncertainly at his surroundings. "I mean, I've met Celebis before, but they never just did something like that; there was one time it happened to someone else, but everything he said suggested that it only happened because the Celebi was under threat and wanted to get away…"

"Under threat?" Clemont looked at Ash sharply. "What could threaten a Celebi?"

"Long story," Ash shrugged as he checked over Pikachu and Goodra, not wanting to dwell on the unanswered questions of what had happened to Sam or the dark time when that man in the iron mask had briefly taken control of Celebi. "Still, if we can just work out where we are, we can probably get…"

His voice trailed as he suddenly heard a pair of voices from further down the road, looking up just in time to see a dark-skinned man and a young red-headed girl walk around a corner in the road, the man wearing brown trousers and a green sleeveless vest over an orange T-shirt while the girl wore denim shorts held up by red suspenders over a sleeveless yellow top as she carried a Togepi.

"Brock!" Ash yelled, standing up to look at his old friends in surprised glee. "Misty!"

"Pikachu-Pi!" Pikachu yelled, joining Ash as he hurried over to greet their old friends, leaving the other three humans looking after Ash in bemusement.

"Uh… Ash?" Misty looked at him in surprise as he stopped in front of them.

"Yeah, I know you weren't expecting to see me, but in my defence, I wasn't expecting this either!" Ash smiled as he looked at his old friends, Pikachu running up onto Misty's shoulder to hug the side of her face. "I just ran into a Celebi and-"

"A Celebi?" Brock looked at him in surprise. "Another one?"

"Yeah, for a legendary Pokemon, we really do keep running into that one, don't we?" Ash smiled at Brock as Pikachu jumped from Misty to hug Brock's leg. "I mean, Johto, Kanto,Sinnoh, and now Kalos? I know that it's a time-traveller, but-"

"Ash, what are you talking about?" Misty looked at him in confusion. "Sinnoh? Kalos? When did you go there?"

"Huh?" Ash returned her confusion with his own uncertain stare. "Misty, I know it's been a while, but I thought Brock told you-"

"Sorry I got held up back there, guys," a new voice said from around the corner Brock and Misty had just walked around. "Bayleef just didn't seem ready to go back in her ball yet; I had to keep chasing her…"

As the speaker rounded the corner, the voice trailed off as he took in Ash's presence, Ash stunned into silence as he did the same.

"Ah," Ash said, as he and Pikachu stared wide-eyed at the unexpected sight of themselves facing them, the other Ash wearing the white-sleeved blue jacket, dark T-shirt and blue jeans that he'd worn when he first started his Pokemon journey so long ago, along with his old green backpack. "I… wasn't expecting that."

He supposed he should have realised that there was something wrong with this situation when Misty was carrying Togepi, but he'd just been so excited to see her again than he hadn't thought about it…

I have no idea what just happened, but clearly things just got very complicated.

AN 3: And there you have the other twist of this story's timeline; I'll establish when it takes place for Ash, Misty and Brock in the next chapter, but I didn't want to info-dump too much at once