Well, basically what happens is: Someone's heart gets taken by darkness, and it makes a Heartless. The body, or shell that's left over, becomes a Nobody. A being without a heart. They say we're not meant to exist.. but.. I don't believe that. Either way, we don't actually feel, it's just all memories, or that's what we're told.

[ sighs. ]

As far as how I lost my heart, well.. I made a deal with the wrong person, and got cheated.