This is the Introduction Guys. I hope it gives a good enough explanation.
anyways, Take it away Gabriel.
Introduction: The First Rift.
The Trickster:
For most mere Mortals the Universe Stands fast, reality holds strong and true, and we are only able to perceive the world around us as a solid fact. Sure something's change, Variables shift, Power moves from one place to another but this is only within the bounds and scope of your Universe.
Notice how I said 'Your' Universe? Are there more?
That's Right. There are many, many more.
These Universes(or This Multi verse) Are all separate, One cannot move from one universe to the next. This fact is held in high regard across all Universes. Some residents of some universe dismiss the idea of multiple universes as Nonsense, BS , A whimsical idea some drunk came up with last night. They would be right in thinking so. There logic isn't flawed is it? Not within the scope of their universe.
However Things are not always what they seem...
Multiple Universes do exist. Each with there own Rules, there own Residents, There own... Struggles. The 'Good Vs Evil' Belief system exists In all universes. on the surface level it is Black and White, Such as the existence of the Grimm on Remnant. The Humans and Faunus are Obviously the Light and the Grimm the Dark. However if we dive deeper, not all Structures are perfect. There are Cracks, Holes, Tears In The Good. Terrorism, Racism, Religious Intolerance, Out right Hatred Exists in the hearts of the citizens of Remnant. Similarly not all Grimm actively hunt Humanity [Including Faunus]. This is a pattern we see across ALL Universes.
Remember When I Said Not all structures Are perfect? The Multi verse For One, While damn Close to perfect, is like a Diamond, with many Facets, not all perfectly aligned. These Imperfections can be exploited, manipulated pulled and torn to form little holes hear and there, little links and portals from one place to another, 'small' connections between worlds that shouldn't Exist.
Let the Fun Begin...