"Excuse me?" Diancie asked, looking up and trying not to fall over backwards. "I was looking for Xerneas?"

She checked her map, looked back down at the ancient town down at the bottom of the hill, then up again. "Am I in the right place?"

"Processing," Regirock said. "Please wait."

Diancie waited.

"Processing complete," Regirock told her, and picked her up. "Rock Throw."

"Wait, what?" Diancie said, but too late.

"Ow," the Rock-type grumbled, picking herself up in a crystal-lined chamber, then brightened. "Oh! Someone I can talk to!"

She brushed herself down, then cleared her throat. "Ahem! Is Xerneas here? I'd like to get some help from her, and I heard that this was where she lived."

"Ooh, good question," Mew replied. "So, firstly, I do have a Xerneas here but it's a he not a her. Secondly, he's having a decade off after spending several thousand years inside the tree here… still, I don't want you to go away without being helped…"

The Mew of the Tree of Beginning hummed to themself.

"I know!" she said, eventually. "I have a dog! They can help!"

She whistled.

"A dog?" Diancie repeated. "And are you sure Xerneas is male? I'm fairly sure that my notes say that Xerneas is female."

"Yeah, but there's more than one of them," Mew replied. "It was a big surprise to me as well, it's amazing what turns out to be stuck in a tree when you don't clear it out for only a thousand years or so, right? You must know how it is."

Diancie's cheeks went slightly red as she thought about some of her paperwork, which now she thought about it might well be halfway to lignite.

Then paws drummed on the ground, and a 10 Percent Forme Zygarde came skidding into the chamber. They nearly rolled over as they skidded to a halt, then ran in a circle chasing their leash three times before stopping and looking attentive.

"So, dog!" Mew clarified. "I don't know how much you heard, but-"

The Zygarde visibly noticed Diancie, and bounded over to jump up at her and lick her face. The impact nearly knocked Diancie over, and she spluttered and laughed. "Hey, stop!"

Zygarde eventually complied, letting Diancie recover, and Mew floated over. "So, what was it you wanted again?" Mew asked.

"Oh, right!" Diancie said. "So I came here looking for Xerneas, but Mew said that you could help?"

"I forgot," Mew admitted, twizzling his tail.

Zygarde's leash-antenna raised. "Contacting AshCompanion Cell," they said. "Please wait, Cell reception can be spotty at times."

"It'll contact Ash," Mew explained. "Who can contact Hoopa, who can probably be convinced to get you to a Xerneas."

He did a loop. "And it also distracts Zygarde from trying to chase me up the Tree of Life!"

"Any rumours that I might be offloading certain morphically resonant base instincts into this particular cell for entertainment purposes are baseless hearsay," Zygarde said. "Woof. Do you think you could throw a stick of some sort?"

They tilted their muzzle. "Alternatively I could be satisfied if you held some Mail and I chased you around while barking. It is up to you."

"Well-" Diancie began, then frowned. "Why are you scratching your ear?"

Zygarde stopped, and looked troubled. "That is a good question."

"Xerneas, huh?" Ash said, thinking. "Did Diancie say what she wanted Xerneas for?"

"That information is not currently available," Zygarde apologized. "I can ask?"

"I have a suggestion," Arc told them. "I believe that this will allow us to avoid the Telephone Problem."

"What's the telephone problem?" Bonnie said.

"It's how if you tell something to someone, and they pass it on to someone else, and that keeps going on… sooner or later you'll end up with the original message completely garbled, because people say it slightly differently."

"That is not what I meant," Arc denied. "What I mean by the Telephone Problem in this place is that you are ignoring a problem solving option that I have, which leaves you with a problem. And I am a telephone."

They pulsed gold. "I will set up an Actual Reality connection in order to minimize delay and prevent misunderstanding."

Then they were in the Tree of Beginning.

"This is really realistic," Chespin marvelled, poking the ground. "How does it work?"

"I did say I was setting up an Actual Reality connection," Arc replied. "It works because we are now here."

"Hi, Diancie!" Ash waved. "Funny thing, actually, we were in Kalos just now… what do you need Xerneas for?"

"Ash," Diancie replied. "And Pikachu. No Mega Stone problems recently, I hope?"

"We did meet someone whose Lucario had a weird reaction to the Lucarionite, but that got sorted out," Ash replied. "Though Croconaw's asked about a Feraligatrnite, if you haven't already made one, in case he evolves."

"I've made a few," Diancie answered.

"Wow, you look really pretty!" Bonnie said. "Are you a princess Pokémon?"

"I always thought a Princess Pokémon would be something to do with Calyrex," Ponyta admitted. "And possibly Flying type."

Since by that point it was obvious that the original conversation had been slightly derailed, Diancie spent a few minutes being introduced to Ash's friends from Kalos (or, in the case of Ponyta, Galar), then the Ash Node of Zygarde started throwing a ball for the Tree Node and Diancie got back to the thing she was originally talking about.

"It's because I need to be able to make a new Heart Diamond," Diancie said. "I've made plenty of Mega Stones, of course, but… well…"

She sighed. "I made the old Heart Diamond all right, I thought, but now it's nearly gone. And it's making me nervous about what I got wrong, so when I try it just falls apart. And I was hoping that Xerneas could help tell me what I missed about making an eternal diamond."

Ash's Yveltal came out of his Pokéball.

"I think I can help," he said.

"Um," Diancie began. "Have I completely forgotten how Xerneas is pronounced and what Xerneas looks like? Because I could swear that that's a Yveltal, except the colours are really odd."

"Hmph," Yveltal huffed. "It's not my fault I'm Shiny."

"It's Ho-Oh's fault!" Tree Mew said. "I know it's very easy to blame Ho-Oh for everything, but that's why I do it! Unless I'm blaming someone or something else."

"Anyway," Yveltal said. "The problem with the idea of making an eternal Heart Diamond is that it's impossible. You can't do it. Nothing is eternal."

He swept his wing out to the side. "Nothing is immortal, nothing is indestructible, because death is a part of the conceptual framework of the universe. Everything has a death, everything has a time, and at the end of all things the last thing to expire will be the concept of death itself and then a new universe will arise from the nothingness."

"Citation Needed," Arc told Yveltal formally.

"Excuse me?" Yveltal replied. "I'm in the middle of expounding a self-consistent philosophy here, don't ruin it with empirical evidence. Anyway, what I was getting at is, because diamonds aren't forever and an eternal diamond isn't possible, you should just make a good diamond and then make another one later when that one wears out. The fact that nothing lasts forever isn't the same as saying everything is hopeless, because the point is the time before the end. That's why everything."

Ash raised his hand.

"Go on," Yveltal invited.

"Well, isn't the diamond the totem stone of Dialga?" Ash asked. "Like the pearl is the totem stone of Palkia and Giratina is probably mirrors or something. Anyway, because of that, if anything was going to be outside the normal consideration of time it'd be diamond, right?"

"That's like saying that pearls are infinitely big," Yveltal said.

"Well, not all pearls would be," Ash corrected. "They'd just have the potential for one pearl to be in all places at once."

He frowned.

"Possibly two. I think Palkia has one on each shoulder."

"So… I shouldn't worry about making a diamond that doesn't last forever," Diancie said slowly. "Because it's okay to have a diamond that just lasts for a time."

"Exactly," Yveltal confirmed.

Diancie focused her powers, and conjured a glittering colourless diamond.

Which lasted two and a half seconds before dissolving.

"Ah," Yveltal coughed. "Philosophical points aside, yes, you probably do need that to last longer."

At Oak Ranch, Shiny Xerneas listened carefully to Diancie's tale.

"All right," he said, eventually. "I've got an idea of what to do here, but first I'm going to ask some questions to make sure I'm confident in my diagnosis."

He knelt down, looking her in the eye.

"When was the last time you did something for yourself?"

"Huh?" Diancie asked, confused.

"I mean what I said," Xerneas replied. "Diamonds form naturally under great pressure, but that doesn't mean you have to put yourself under it. Speaking as an incarnation of Life, what you should do is enjoy it a bit."

Diancie looked slightly lost.

"What would that entail?" she asked. "And I'd feel like I was wasting time while-"

"Stop," Xerneas interrupted. "What gives meaning to life is what you do with it. So do some."

"That sounds strangely reminiscent of what Yveltal was saying?" Diancie said, half-confused and half-protesting.

"Then I suggest you agree with both of us," Xerneas added. "In fact… here's an official instruction from me. Make some friends. I'll judge when you've done it."

Ponyta mumbled something about how that didn't seem appropriate in a situation where there was real trouble ahead, but Serena shushed her.

"I'll help," Sandile said. "It's time for a montage!"

"I'm not sure what a montage is, but this has been nice," Diancie admitted, the next day. "I know that the Diamond Domain has me for a princess, but we don't do nearly as much royal pageantry as the Ryuunited Kingdom does."

She leaned back into a comfy cushion. "The fireworks are especially fun."

"Yeah, they're really pretty!" Bonnie agreed. "All the Dragonite are so sweet, too! I think it's because King Dragonite loves hugs so much."

"I didn't know some of those things they were doing were possible," Dedenne contributed. "What's that thing that made the whole sky turn green for a bit, until Zapdos folded it into a ball?"

"Dracorocco," Sandile told them, popping up next to their chairs. "Thing is, I don't think this has been a proper montage… this is the problem with relying on a montage when you don't know Cut yourself, you can't trust that you get the right scenes in…"

"I don't actually understand what you mean," Diancie confessed.

"It'll make sense at some point, probably," Sandile shrugged, then popped back down.

As girl, starter and legendary tried to work out how to react to that, Zygarde came loping over.

"Attention," they requested. "Life and Death are on the line."

"They are?" Diancie gasped. "What went wrong?"

"Nothing," Zygarde clarified. "Xerneas and Yveltal have a suggestion."

They tilted their head. "I will attempt to be clearer in future."

"Oh, phew," Bonnie said. "I was worried!"

"I was worried too," Diancie admitted.

"Their suggestion is: Diancie, try making a Diancite," Zygarde said.

"That's an interesting suggestion," Diancie said, and focused. It took a bit of concentration, but then a glittering spherical Mega Stone formed in her hands.

"Good," Zygarde declared. "Bonnie, please take the stone and think of Diancie."

Mega Diancie felt a lot better after that, and after a little advice from Servine she put her hands together and manifested a Glittering Thousand-Year Diamond that was (at least according to Servine) touched with the power of the moon.

After that, everyone went back to Kalos with the knowledge of a job well done and the memory of a comprehensive Dragonite hug.

"...I don't think Diancie's coming this way, dad," Millis Steel said. "We've been waiting days now."

"Probably," Argus Steel admitted. "Still, I did have this other plan."

He spread his hands. "What do you think about running a chocolate shop?"

Millis blinked. "What? Why?"

Argus seemed a little confused by the question. "...chocolate is nice? Do I need to have any more of a reason?"

AN:

And that's the first Kalos movie, which is entirely not in Kalos. Except for that bit at the end.

As the first year of this fic ends, I've managed a slightly baffling 587,000 words or so…