"Zulf could just get it from Zia if he wanted it. You and I have no reason to go after it, and Nathaniel made it pretty clear that he didn't want it used for anything, which is why he hid it in the first place."

Bon didn't know Colin as well as Rin did, but if she's sure he wouldn't be after the journal, he'll trust her.

"Someone else has to know about it. That's the only explanation. Someone knows about the journal, and they found out that you had it somehow."