I Want the Protagonist to Be Really Vicious and Especially Good at Pretending

I want to read a book like "Quick Travel: Love at First Sight". I have read a lot of novels in which the protagonist plays the role of a vicious cannon fodder and is exposed. I want to read the opposite. Please recommend a novel in which the protagonist is a duplicity. He is innocent and kind on the surface, but is actually a vicious green tea. You have to be very good at pretending.