It's kind of funny you say it like that because there was a whole group that we were fighting against that wanted to use to darkness to destroy everything so they could get their hearts back and feel emotions again.

[Hopefully he's not making your head hurt too much, Zack....

Because it's all about to get even weirder now.]

No--well, sort of? [Sora hums thoughtfully then.] Kingdom Hearts is..it's the heart of all worlds. It's what everything we know and experience comes from. All worlds are connected to it just like all people are. So if we lose Kingdom Hearts, we lose everything.