Hey there!  
First, I'm very interested in this.
Second, what do you mean by people with enormous potential for power?  Are we talking actually abilities, or is it more along the lines of super effectiveness against demons (thunder against water in pokemon) or just great amounts of latent talents?
Third, what kind of demons are these?  I'm assuming closer to the traditional idea of forces of evil, as you mentioned balance, or are they supposed to be something else?
Forth,  What is the technology level for this rp?  At first I thought it was fairly advanced since you mentioned people from different worlds but they it says that crazy cyborgs aren't a thing.  So I"m a bit confused on this point.