How does Meg's character change as she responds to events during the book?

As the protagonist, Meg changes a great deal throughout the novel. When we first meet Meg she is insecure, awkward, and impetuous. Meg's insecurity is most obvious at the start. She's doing poorly in school, she hates being compared to her parents, and among her peers she's said to be immature.

As the novel progresses, Meg begins to come into herself. On her quest to find her father, Meg finds herself responsible for her younger brother. She has to step-up and use her intelligence, all while falling back on the love she feels for her family. She also has to open herself up to new experiences and people (creatures), she has to learn to trust, and most of all..... she has to learn to trust herself.

By the end of the story, Meg has matured and grown-up. She's learned to love and trust unconditionally and without fear. She puts the love she has for her family before her own fears and conquers those fears.