There is "not enough" trend in this book, IMHO.
Human Bart's not sick enough the way his illness is described.
Pest does not care enough & not emotional enough. He is detached and doesn't spend enough time with Bart.
Pest and Death talk about secrecy but they are not secretive enough. In fact they can't seem to keep their mouths shut.
The whole falling in love process is not convincing enough.
The whole case of pandemic about to explode is not believable either.