Petit, the Monster by Isol, translated by Elisa Amado (Groundwood Books, English translation c. 2010)
Petit is a good boy who sometimes chooses to display bad behavior. Sounds like most children, right? "His mother asks him, "How can such a good boy sometimes do such bad things?" Good question...and Petit just doesn't know the answer, because it's a difficult question to answer (especially if you're a kid). So, he takes a look at ways he acts both good and bad and he comes up with an answer for his mother. Kids are sure to relate to this book from Argentine children's author and illustrator Isol.