The youngest child of the Thibaut family, Amélie, who mostly goes by her real name, gets away with a lot because she looks so sweet and innocent that no one suspects her. She's a friend to Maddie at the Thibauts', and in the end, she's the one who completes Julie's mission of getting information about the Ormaie Gestapo building out of City Hall.
[T]hey didn't even look at Amélie's ID—she said she was working on a project for school, easy peasy. She was supposed to say she was verifying a boundary of the Thibaut farm, but when she saw how easy it would be to get in and out, she made up a simpler story on the spot. She is sosharp. (2.23.1)
She reminds us of the kind of kid Julie must have been. Though she is very young, Amélie repeatedly risks her life every bit as much as the others do, proving that the Nazis are not as smart as they think they are to ignore her.