Not long after they got back to Alola, Ash vaguely realized that there was fog all around him.

"Huh?" he said, confused. "This is weird…"

"Ash?" Pikachu said, appearing out of the fog and bounding up to him. "Any idea where we are?"

"No, sorry," Ash replied, reaching down to his pocket, then frowned. "Huh, no sign of Arc or Ibid… this is weird. Something about it is familiar, though."

"I kind of get what you mean, but not quite," Pikachu said, then shrugged, and used his Surfboard to rise up into the air a bit.

"I can see mountains all around us, through the fog, but it's all a bit vague," Pikachu reported. "There might have been something different that way, though."

He waved his paw, and Ash nodded.

"Let's go and see what it is, then!" he invited.

The mountains around them moved, slightly, as they walked, and the fog seemed to recede a little to reveal pillars of rock around them – some of them carved into unusual or special shapes. And ahead of them, a flight of stairs.

Then, at the top of the stairs, a flat topped construction built out of stone.

Light swirled overhead, and two Legendary Pokémon appeared from the mist in swirls of multi-coloured light that formed tunnels to infinity.

"Hi, Solgaleo!" Ash waved. "Hi, Lunala! Hey, where are we?"

"Hi, Ash!" Solgaleo replied, waving, then Lunala coughed and the Sunne Pokémon shook his head slightly. "Right, sorry."

Then a third Legendary Pokémon appeared.

Unlike Solgaleo and Lunala, the third to appear just sort of dropped herself into the space overhead.

"Ahem," Cresselia said. "Yes, hello, do come in, welcome to the dreamscape, I accept your apology for not giving me advance notice."

"That's what I forgot to do," Lunala said, hovering overhead and contriving to look embarrassed.

"And, speaking of," Cresselia added, and turned off the fog. It vanished in an instant, giving a perfect view of an ancient temple surrounded by sandstone spires and the edge of a canyon, and Lunala coughed.

"You do realize we're going for something approaching ceremony, here, don't you?" the Moone Pokémon asked, with a sweeping beat of her wings. "I'm just saying, we did put in a lot of effort to do this."

"So, if you're in a dream, I guess that explains why Arc isn't here!" Ash decided. "Should I get Giratiny in here? He's sort of made of dream… or is that not relevant?"

"This is why I love how Ash deals with things," Solgaleo said, in what was theoretically a quiet voice. "It's just great."

"Ash, is this a nightmare in any way, shape or form?" Cresselia checked.

"Not at the moment!" Ash said. "If Solgaleo and Lunala want a bit more spectacle, could you do some?"

Cresselia waved her hand in a vague sort of way, and the sky overhead split neatly in half. Solgaleo's side became a blazing sunlit day, and Lunala's side a starry nebula with the full moon shining down.

"Ooh," Solgaleo said. "I am seriously impressed."

Lunala coughed again, and Solgaleo nodded. "Right, right."

"Ash Ketchum," the Moone Pokémon said. "We have a job we would like you to do."

"It is not something you have to do, but it would be really good if you could," Solgaleo agreed.

"We can think of none better," Lunala continued. "Your task, should you choose to accept it, is to take care of Cosmog. The Guardians will show you the way."

"Cosmog evolves into Cosmoem, right?" Ash asked. "Mew showed me both of them once, then giggled a lot. The lightest and heaviest Pokémon, or something?"

"Yes, though a lot of that weight doesn't actually exist a lot of the time," Solgaleo said. "It's Ultra. I'm not sure the details but it's Ultra Ultra."

"I have questions," Pikachu said. "Firstly, when you say take care of, that's basically to the same extent Ash takes care of any Pokémon, right?"

"Honestly, nothing I've ever seen from him suggests we'd want anything more," Lunala nodded.

"Secondly, now that I get a close look at you two… Cosmog is your kid?" Pikachu said.

"...you actually weren't meant to work that out until Cosmog was old enough to evolve to their final form, but yes," Solgaleo conceded.

"Thirdly," Pikachu concluded. "Which Guardian?"

"Tapu Koko," Lunala said. "Why?"

Pikachu shrugged. "Just curious."

"Sure!" Ash decided. "Of course I'd take care of them anyway, but I'll make it a promise!"

"Morning," Rowlet chirped. "Litten's off visiting Stoutland. You took a long time to wake up this morning!"

"Turns out they were involved in a dreamscape," Cresselia provided. "A dreamscape run by Pokémon who could do with a bit more imagination, too… still, no harm done."

"Thanks for checking on us, Cresselia!" Ash said, yawning and stretching.

Then Tapu Koko threw Cosmog through the door and ran off.

"Hi, there," Ash said, once he'd caught Cosmog in the no-actual-Pokéball-involved way. "It's nice to meet you, Cosmog."

Cosmog floated up and down, waving their nebulous arms. "Cosmog! That's me!"

"That's right," Ash agreed. "Do you know a lot about what's going on?"

That made Cosmog look puzzled. "Umm…"

"It's okay if you don't," Ash assured them.

"Oh," Cosmog said. "No then."

"Well, I got asked to look after you," Ash explained. "I'll do my best, okay? If you're not sure about something, you can say, and I'll try and work out if I can tell you how it works."

Lycanroc padded over, and sniffed Cosmog.

"Nope," they said. "I have nothing useful to contribute."

"I have no idea what kind of Pokémon Cosmog is except that it is Cosmog!" Rotom announced, floating over, and leaned in close – which made Cosmog bob backwards a bit.

"Careful you don't startle them," Ash advised. "Ibid, do you have anything?"

"Cosmog," Ibid reported. "Psychic type. Its body is very light, but it doesn't seem to mind being blown away. When it's in trouble, it warps to a safe place to hide."

"I don't know what a lot of those things mean," Cosmog admitted.

"That's okay," Ash smiled. "That just means you have more things to learn, that's all."

Litten came in through the door.

"Morning," she said, then stopped. "Wait, is that new or not? I legitimately have trouble remembering."

Cosmog waved, then giggled as Litten jumped up to get a closer look at them.

"Hmm," Pikachu said, thinking out loud. "Warping to a safe place… that sounds like teleporting to me. Maybe they can learn to teleport?"

"That sounds about right," Ash agreed. "That means that Cosmog could learn from Ibid, right?"

"Or Raikou or Shaymintwo," Pikachu pointed out. "Well, Raikou mostly uses thunderbolt riding to do it, so that might not work so well for a Pokémon that's not Electric type, and Shaymintwo… I guess we can always try it."

"Teleport?" Cosmog repeated. "What's a teleport?"

"It's when you move without having to go through the space in between," Ash told them. "So if I could teleport, I could vanish from here and appear somewhere else without walking. But because I don't, I have to walk."

"Oh!" Cosmog said.

Then there was a flash, and suddenly they were in a seaside cave.

Gladion jumped. "Where did you come from?"

"Professor Kukui's house," Ash said, as Cosmog looked around. "Just now, anyway. If you count further back then Pikachu and I are from Kanto-"

"I meant just now," Gladion said, relaxing slightly. "Ash, that was… so strange. You just appeared out of nowhere – and what is that Pokémon?"

Silvally came out of his Pokéball with a flash, and gave Cosmog a long, measuring look.

"Nope," he said.

"Silvally, don't do anything hasty," Gladion said.

"I wasn't… going to," Silvally replied, sitting back on his haunches. "I was made to… fight Ultra Beasts. But…"

He shook his head. "If this little one… is an Ultra Beast… then I feel no need to fight."

"Oh, huh," Ash nodded. "Silvally says that he was made to fight Ultra Beasts, but if Cosmog does count as an Ultra Beast then it's not one he feels he needs to fight."

Ash paused. "What's an Ultra Beast?"

Gladion did explain everything he knew about Ultra Beasts, and so did Silvally – in his halting way, as best he knew – but there wasn't really much to say.

Ultra Beasts came from Ultra Wormholes, and they were in some way dangerous. Silvally had seen one only once before, in something that he didn't really want to talk about all the details of, and it was so obviously making him uncomfortable that Ash didn't want to ask.

"So… I guess we know some Ultra Beasts are dangerous, but we don't have a reason to think they all are," Ash decided. "Even if just because it's way more likely that one would come here if it wanted to cause trouble."

"That is a good point," Gladion said. "What do you think, Silvally?"

"Your words make sense," Silvally agreed. "I will do what is needed… to protect my friends."

He shook his head. "Not… endanger them."

"That's good," Ash agreed. "Keeping friends safe is important, but causing trouble that could hurt friends is an easy way to make a massive mistake."

He turned back to Cosmog. "So, since we know you can teleport, what about making it work better?"

"Teleport?" Cosmog asked.

"Making sure you know what you're doing, and that you don't do it by accident," Ash clarified. "Does that make sense?"

"What's an accident?"

"It's when you do something you didn't mean to do," Ash told the Psychic-type. "Usually you want to make sure you only do the things you want to do."

"Oh, okay," Cosmog decided.

"What made you decide to teleport here?" Pikachu asked.

"It's what that orange one was thinking about!" Cosmog explained, waving vaguely in Lycanroc's direction. "They were thinking about walking to go and visit their friend, and then we came here."

"Oh, that must be Gladion's Lycanroc," Ash said. "That's neat, but it's best to only do that when someone asks, okay?"

Cosmog nodded, a sort of bobbing movement.

"So, what about if we go back to Kukui's house?" Ash suggested. "Then you can meet some of my other Pokémon, and we can work on teleport!"

He paused. "Actually, hold on. Let's walk, okay? Lycanroc, if you want to have a chat with Gladion's Lycanroc let me know, and you can come back on your own later."

"That would be nice," Lycanroc agreed. "Thank you."

"Walking takes a long time," Cosmog decided, as they reached Kukui's house again. "Why doesn't everyone just teleport?"

"Because most people can't," Ash said. "Arc can, and so can Ibid – they do it different ways – but if you do things the easy way it sometimes means you miss about out on things you could find along the way."

Cosmog looked puzzled, so Ash decided to go into more detail. "So early on my Pokémon Journey I went from Cerulean City to Vermillion City, and I could have just teleported there, but if I had then I'd have missed meeting my Charizard. And he's a great friend."

"Oh, okay," Cosmog said. "So… it's sometimes okay to teleport, but not always?"

"Right," Ash agreed. "There's no one rule for when it's okay, but it's something you have to learn for yourself. It's also okay to ask if you're not sure."

"Got it!" Cosmog declared. "Is it okay if I practice, then?"

"Try teleporting just over there," Ash said. "Hey, Litten, mind going over there to show Cosmog how far to go?"

Litten raced down to the palm tree Ash had pointed at, then skidded to a halt.

"See where Litten is?" Ash asked. "Think you can go that far?"

"Alola, Ash!" Kukui called, waving from up the beach. "I thought I'd come back here for lunch… how's it going?"

"Tapu Koko dropped off a baby Pokémon called Cosmog after I met I-guess-the-parents in a dream!" Ash explained. "They're learning how to teleport and how not to teleport!"

"The second one is more important sometimes," Kukui confirmed. "You're next doing a lesson… day after tomorrow, right?"

"That's right!" Ash agreed. "I've got a couple of ideas about what to do!"

AN:

Cosmog's not dense enough to break windows.