Arceus stirred, and his ring flashed golden.
"Report," he said, in a tone of brass and gold, and his eldest three children – Dialga, Palkia and Giratina – materialized in front of him.
"What happened?" Arceus added. "I felt something happen."
"The outside galaxy has touched us," Palkia said. "We knew the veil was weakening, but this has formed a second connection to the outside galaxy this century."
She looked at Giratina, who took up the thread.
"The veil was a long-term solution, but it was never going to last forever," he said. "We are going to have to prepare for when it tears for good, and that will happen – soon."
"Then prepare we shall," Arceus decided.
His ring glowed as he reached out into the pocket of time, space and dimensions around the world he had claimed, and felt the currents of emotion and existence.
It was… good.
Arceus had not truly touched the world he had created and nurtured in such a deep way, not for over a thousand years… not even in the greatest crisis before now… and he wondered when he had come to lose the habit. But now… now, the world was a shining beacon of glory in the vastness of space around it.
A testament to what could be done by cooperation. Everyone on the planet below and around him lived in a Pokémon World, one built out of a recognition that those who worked together were far stronger than those who did not.
There were battles, but they were for fun, and everyone understood that. Humans worked with Pokémon, Pokémon worked with humans. That was as it should be.
A child of ten could go out into the woods by themselves, and make friends with any human or Pokémon they found there, and the friendship could last a lifetime.
The contrast with what he remembered of the galaxy, six thousand years ago, was… breathtaking.
"What a world we have made," he said, turning his perception back to his eldest children. "What a world. I am proud of you all."
He turned his attention back to Palkia. "So. What happened?"
"Some kind of incursion from the ethereal realm," Palkia told him. "Whatever it was, it traced the path from what happened last time."
Arceus looked grim. "Then the Chosen One may-"
"No," Dialga interrupted. "Sorry, Father, but… you don't need to worry. The Chosen One is fine."
"He is?" Arceus asked. "Forgive my confusion, I'm relieved, but… how can that be?"
"That's one weird Pokémon," Ash said, scratching his head. "And super aggressive, way more than any Pokémon I've ever met before. What type do you think, Pikachu?"
"Kaa-Pika?" Pikachu suggested, twitching his ears. "Pika-pikachu, chuuu…"
"Dragon?" Ash replied. "I guess it does have those scales and stuff… or it could be Fire-type or something. But my Pokédex doesn't have anything about it."
He checked again, just in case, then shrugged as his Pokédex stubbornly failed to identify the smoking and unconscious creature in front of him. "Maybe I'll ask Professor Oak if he's ever heard of a bloodforthebloodgod. It's a really long name for a Pokémon."
AN:
Formed out of a discussion of how to cross over Pokémon and 40K, and I took it in a silly direction.
The fact that Ash is the missing Primarch of the 2nd Legion is, somehow, not the most disruptive bit of adjustment this did to the setting.
Conceptually, the idea here is that the Pokémon World's general optimism and benevolent setting rules are so strongly ingrained that they actually overcome the 40K 'verse's general ultraviolence and pessimism.