Quote Originally Posted by Ouch! View Post
I was under the impression that shadow heartless existed before the experiments and that all the other "variations" of heartless are merely the result of the experiments conducted in Hollow Bastion. I thought they'd always been around, but in numbers too few to pose a threat, and they'd merely been mass manufactured during the experiments.
I interpreted it as that his experiments included the "research of the Heart" even before he got to the mass-manufacturing, which is the first time that the players knows that a character interacted with a Heartless, for sure. One can relate the growth of Heartless to the breaking of the Gummi barriers that protected each world. Though it can be said that they destroyed worlds before, there was no way for each Heartless to get past the Gummi barriers until Mickey and Ansem's attempts at stellar communication.

In effect, they could exist, but no appreciable effect could be felt elsewhere and only for that world. They would have to formed only on that world.