SO! Vampires in Chris's canon largely function as sort of symbiotic social parasites to humans.
This post goes more into all of how that works/why (or will, I'm still typing it all up), but one of the more notable aspects of this is that they are
very good at reading scent, body language, etc. and interpreting it to the point where they can read moods about as well as someone with empathic powers would. Note that this will not work as well on people who can control their reactions very well, or with thoroughly nonhuman body language or scents (although if he interacts with someone who falls into the latter category enough, Chris will start to learn their particulars.)
If you would like to opt out of this or tell me what Chris would be able to read/how difficult it would be to do so, please drop me a comment here! As a note, though,
I'm generally going to assume that thoughts or reactions in bracket tags are things he can pick up on unless told otherwise.