Clary Fairchild: How did you know I had Shadowhunter blood? Was there some way you could tell?
Jace Herondale: I guessed… It seemed like the most likely explanation.
Clary Fairchild: You guessed? You must have been pretty sure, considering you could have killed me.
Jace Herondale: I was ninety percent sure.
Clary Fairchild: I see… (Clary slaps him)
Jace Herondale: What the hell was that for?
Clary Fairchild: The other ten percent.
From the book The Mortal Instruments: City of Bones (Book One) | Written by Cassandra Clare