[There's a pause. After a moment comes a thoughtful reply.]

...The stopping is easy. Just don't use darkness. The reversing... I don't know. I... I don't know any of that. [His attempts to hide his concern are weak.] There's still a lot about hearts we don't know.

I... I still use darkness, even almost becoming a Heartless. Just not the same way. So the heart has to be healing...