Her remorseless side is shown early on in the novel; she makes up stories to her parents and teachers to make her life more convenient. Although Charlotte never expresses regret over these fibby fabrications, her parents begin to catch onto them by the end of the book. She is quite polite and compassionate to those she grows to like, such as her cousin Zachary and her teacher Mr. Metos.
Charlotte's cowardice is evident in the book (she even admits to being a coward at one point) but there is a definite turning point when Zachary is sleepwalking outside with the aberrations known as Footmen (the scary bad guys, basically) likely stalking him and Charlotte rescues him. From this event onward Charlotte is brave in dire situations. She enters the Underworld through a very long dark corridor, fights the Footmen and kills one of them, and handicaps the main villain Philencron by pushing him out of his throne onto the burning ground at the end of the book.