Basics on undertale Alternate Universes

In the Undertale fandom, Alternate universes have drastically different lore and rules compared to other Au rules. Like the fact that sometimes creators of aus, yes the real life creators, are sometimes canon as god like beings. So if you made a vampire au of a character YOU are their canonical god in undertale Au logic.

Heck sometimes the characters are forgotten or scrapped irl, them and their world either fade away or see a much worse fate Canonicaly.

But this opens a much bigger question..

What are alternate universes to the undertale fandom?

In this book I'll explain undertale universes and how they work, I'll explain the concepts like multiverses , alternate Timelines, ect. And also characters. You can request some if you like. :D