"Huh? Yeah, it was a bit confusing for me too but it's χ like a weird X rather than key like a key," Sora explains sheepishly. "I didn't get it 'til I saw it written down in a book."

But at Roxas' question...

"I don't think he can do anything with everyone asleep, but the worst part about Xehanort is there's already, uh..." he quickly counts on his fingers, "six of him, if you include the half-Xehanorts, and one of the full Xehanorts can time travel so that really sucks."