"Lost their soul? No, can't say I do," Lea said. "At least, no one who did and was still around to worry about it afterwards."

"See, where I'm from, a soul is just the force than animates you and keeps you alive," he explained. "You lose that, you die, plain and simple. It is possible to survive losing your heart, though, at least partially. The heart is what lets you feel things, connect with people, and basically holds everything that makes you you instead of just a living body."

"That's what a Nobody is; a body and soul, with no heart. Or at least that's what they start out as. Turns out, a person who loses their heart and gets turned into a Nobody can sort of... grow a new heart over time. Xion and my old boss Xemnas knew this all along, but kept it to himself, since his plans required the Organization to be a bunch of empty shells, and for them to think that following him was the only way they could ever be whole again."