I don't think you understand the plot. 

Your character will be a resident of one universe. This can be a canon (such as Naruto from Naruto) or an Original Character. This roleplay will take place in one world in one universe; the empty world in Minecraft, with no mods installed. The members' characters will somehow find this universe and live here. 

The "cross-overs" or "quantum car pileups" work like a Venn Diagram, where each circle is its own piece of paper. The different universes are close, but do not touch, until for some unknown reason, they overlap. That is a crossover; a point where two or more universes connect. When more than two universes connect, the fabric of reality starts breaking down. Too many connections can cause the universes to cease to exist. Those who managed to escape--usually by getting lost in some universe other than their own--now have no place to live. Our town of New Haven in the Minecraft world accepts all immigrants, as long as they work. And that is the plot.