But people can still turn into heartless in the realm of light.either by being attacked by a heartless or by succumbing to the darkness in their own heart, as explained by Yen Sid and implied in countless other instances: "If one such as you, Donald, yields to the darkness in their heart, they too will become a heartless."
And as we know a nobody can be created through either way.
of course without any heartless avaible people are unable to lose their heart to those, but I don't see any reason why people should be unable to succumb to the darkness in their heart during the bbs-timeperiod. In fact, the xehanort reports imply that this is exactly what happened sometimes.
Spoiler ShowAt present, the lanes and corridors that run between the worlds may only be traversed by us Keyblade wielders, and those who have given themselves over to darkness.
As the former, our duty is to cross the chasms between the worlds and guard against the latter, whose darkness corrupts and contaminates, so that no world need ever be lost again.
you're right. completely forgot that actual hearts are needed. well, that's that.
Would be pretty much impossible if heartless can't enter the realm of light at all. In the time of BBS heartless were completely unknown in the RoL, the Keyblade Graveyard (where MX summoned the neoshadows) is an in-between world.
As far as we know, nobodies only came into existence first due to Apprentice Xehanort and his experiments, before that nobodies didn't even exist.
Succumbing to darkness does not always mean becoming a heartless and also surely means not a nobody. Nobodies are, after all, beings between light and dark.
Yep, two hearts have to intersect or it won't work.