A drop here, a drop there (a one-shots/snippet book)

Undertale Time Loops Part 2 (Undertale/Multi)

Explanations

Sans eyed the pokemon in front of him. It looked like a fat yellow mouse, with rabbit ears and a lightning bolt shaped tail. It also started talking once they were alone in the road, much to his surprise.

Pokemon, based from his new memories, seemed to be the only types of monsters that can do magic in this world. And even then, they were different from monsters like Sans, in that pokemon, while having the appearance of monsters, are made from flesh and bone like humans. Pokemon also can't speak, they are more like wild animals and needed the command of humans and greater monsters to perform (and learn) more complicated strategies.

Apparently, this pokemon was an exception to that rule.

"What do you mean if I'm feeling loopy?" Sans asked, confused.

The mouse pokemon hummed, "Has time been repeating for you?"

The skeleton hesitated. After all, time has always been repeating, it was only recently that he remembered them. Is it possible this pokemon is in the same situation? "Yeah. I guess."

The pokemon–pikachu was it?–sighed and said, "I guess it's time for a 'Welcome to the Multiverse' speech. But first, how about you tell me about your world first?"

Sans blinked, and the scientist within him straightened up in attention. "Multiverse? There really are multiple universes? And we are in a different world?"

Pikachu waved a paw impatiently. "Yes, yes, tell me yours and I'll tell you about mine and this whole time looping situation."

At the promise of finally getting some answers, Sans told him about the Underground. About the war between humans and monsters, and the monster's sealing underneath a mountain. About King Asgore's plan to use seven human souls to break the barrier. About the fallen human with the power to reset time and played with the Underground again and again and again. Though Sans only got vague knowledge and feelings on what the human had done the previous resets, he didn't remember them.

Until he woke up back during a time before he met the human, the previous reset clear in his memory. He told the pokemon of his observations on the human, and how everything they did was the exact same as the previous resets since his awakening.

Pikachu listened intently, and when the skeleton was done, muttered something about "Re:Zero" and "play thing"

After that, the pokemon insisted on finding a clearing first where they can talk with less chances of someone walking in on them. Thus, they walked off road for a while until they found one and the pokemon ordered him to sit against a tree. The pokemon reached into thin air, and Sans' eye sockets widened when the pokemon pulled out a chart out of nowhere. Then the next moment Pikachu is wearing glasses and holding a stick.

On the chart are the words "Welcome to the Multiverse"

And so, the situation was explained to him.

Reality is a World Tree, though it was more of a super computer than an actual tree, called Yggdrasil. It is made out of an infinite multiverse divided into billions and billions of realities, some of which has their own sub realities and planes connected to them. A long time ago, something happened that damaged the World Tree, so the gods, or Admins, decided to put a few of the worlds in kinda like a 'safe mode', where it will keep repeating during an important part of the timeline while the gods set to work on fixing whatever the damage was. Seven worlds were put into loops by the Admins, then others followed in time.

Each world needed an Anchor to keep it stable, and they are the first ones to wake up and become aware of the loops. Pikachu is the anchor for his pokemon world, and apparently, Sans is the anchor for his world in the Underground. Anchors also trigger other loopers to awaken around them, usually those who have a significant relationship with the Anchor.