So it was stated that the will of the dark fountain decides like the world and the darkners my theory is that when a person who has never been to a dark world before inherits some of the dark words traits.

Example kris and berdly both being knights but both suited to the dark world they first entered. Kris having a normal suit of armor with a raggedy cape with a dark color plate but berdly on the opposite side of the spectrum has a lighter color plate and more neon colors, a dragon Ball reader, and a neon glowing weapon that can change its shape. (that’s reminds me of a light saber but that’s not important to the theory)

Yet when kris enters the cyber world they still keep their mid-evil vibe and so does Susie but this could be doe to them first entering a dark world made from pure dark fountain but even ifs that’s true they still hold a bit of the will of that dark fountain.

And then there’s noelle who gets a classic white rob who kinda throws a wrench in the theory but not really actually, she may get a fantasy esc outfit (maybe because of her favorite game) she still gets a lighter color palette compared to her light world or well more paler but yet her color Palette changes to fit the neon color palette of the cyber world.

Also mini theory the reason why ralsei can go to different dark worlds with out turning to stone maybe the same reason why other darkners from different dark worlds can live in his dark world with no problem.