"She interrupted herself by racing over, placing her hands on his. Magic was starting to force its way out of them, but it wasn't Medal-made - it was just raw, powerless darkness, digging its way in to stitch up the seams."
"..She was trying not to look down at how red her hands were, and *still* were, even after wiping the blood off them."
Aria is vulnerable to those that wield Keyblades, just like any other Heartless. And, without one of her own now - as Dark Diamond was broken in the fight with Zero-Kiru - that means she has to fight like a Heartless for the time being, too.
And when you send too much darkness through the body of a human, which is very much not something intended to wield too much of it at once? Well, that's how Darklings happen, eventually, isn't it?
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