[Uh oh. Is having a potential killer in the apartment straining things between Reid and Kitty? Did Nathan mess something up? He probably messed something up by virtue of existing and Kitty doesn't want to freak him out by saying something. (Nathan's brain is almost as good at making everything about him as it is at dredging up worst-case scenarios.)
But saying something is out of the question, so he takes the pie with an automatic thank you and sets about dissecting it with a fork.]