Graves is a vampire. Oddly enough, so is Newt.

To be more precise, Newt is the most atypical vampire ever, and Graves, who has been raised with the more 'stereotypical' vampire attitude, can't quite understand why he is so fascinated with this bundle of sunshine (not literally!) and good intentions.

+ Graves doesn't realize that Newt is a fellow vampire at first.

++ Newt actually /isn't/ a vampire - he's a dhampire, half-vampire.