Kind of darkness? ...Where I'm from, all darkness you use comes from your heart. Same goes for light. So if you use dark magic, you'd be using your heart's darkness, probably. It's how it goes where I'm from.

But where I'm from, you can't store memories outside your heart. If all my memories were taken out, my heart would collapse. And I'd be a Heartless just from that.

Maybe it's different for you.