These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Monster Blood Tattoo
Crowning Moment Of Awesome - these seem to follow Europe around, but the QGU scene at the end of the second book stands out. Rossamund also gets his share.
Crowning Moment of Heartwarming - in the third book, when Rossamund goes to tell her that he's a monster after all Europe doesn't care. He hugs her, and after a moment, she hugs him back and murmurs about how ironic it is that he's captured her affections. D'aww.
Genius Bonus - to someone with a background in linguistics (particularly Germanic and Romance languages), a lot of the dialects and slang feel like a Bilingual Bonus mixed with a little Buffy Speak.
I Knew It - Rossamund being a monster was fairly heavily implied before it was actually revealed
Jerkass Woobie - Threnody's jerkass attitude is due in part to being very upset with her mother for forcing her to undergo a body-transforming operation she didn't want.
Moe - Freckle. Squee. Not to mention Rossamund himself!