Sophie Foster, main protagonist in Keeper of the Lost Cities by Shannon Messenger, is one of the most important characters ever. She is a fascinating elf, one with a foot in both worlds, human and elf. When Fitz Vacker declares she is an elf, Sophie was reluctant to believe him, but quickly overcame that doubt. She traveled all over the world, trying to save the world from an evil organization called the Neverseen, and proven herself as both powerful and loyal. She is surrounded by a group of friends that adore her, and they are most steadfast.