c1
[The library is one of a number of places Zero often visits. He was really just passing by Ai's table, rather than actively seeking her out - she's not causing any issues, so he has no real reason at the moment - but soon finds himself approaching anyway. Her question is one of the reasons.]
Did something happen with it again?
[Even before responding one thing she will notice is the lack of the hunter's charm on his throat, and, well. The fact that he won't give off the presence of a vampire at all.]