Charlotte is a nine year old girl who is a great violin player. She took shelter in Saint Paul's Cathedral until deciding to leave along with Ed's group. She is called Yo-Yo by The Kid and it became her nickname.
Charlotte was first seen when playing the violin for The Great Song in Saint Paul's Cathedral. When The Kid was speaking to her, she replied by saying she wasn't allowed to talk to him or she'll be punished however, The Kid continued speaking to her, giving her the nickname Yo-Yo and complementing her violin skills. Although she was supposed to be playing the great song via Matt's orders, she was playing Beethoven instead and blushed when The Kid noticed.
She appears again when the Cathedral kids march The Kid and Sam down to the warehouse they keep Wormwood to see which one of them will be sacrificed. She is in the group of the best musicians.
When Ed asks if anybody wants the Cathedral to leave she is the first to answer saying she'll come. She admits to be being religious but thinks what Matt is doing is wrong, she also went because she thought The Kid was nice and funny, and it wasn't right to sacrifice him.
When Ed's group is under attack by an small army of sickos when leaving the Cathedral they have to retreat into a building. When hiding in the building with Sam she begins to cheer him up by saying how good a person The Kid was. When she finishes speaking, The Kid shows up unexpectedly and tells her not to stop her speech.
When they make there way over the bridge again with Wormwood's help, he signals to the other sickos and they all freeze, but he has difficulty controlling so many sickos. As the kids start running through the path of "frozen" sickos, Wormwood loses control of them and they all start to attack the kids. The older kids are fighting their way through the crowd of sickos and Adele especially protects Charlotte, Sam, and The Kid. Every time a sicko gets near them she kills it, all the while smiling encouragingly at Charlotte. This reminds Charlotte of a stewardess on a plane who smiled at her when she was younger and had been afraid of flying. Adele eventually gets dragged away by the sickos; but Charlotte, The Kid and Sam all escape.
Charlotte was first seen with Paddy, Wiki, Jibber-Jabber, Zohra, Froggie, Blu-Tack Bill, Small Sam and The Kid mentioning names for Paddy's new dog.
She appears again in the Natural History Museum library with Small Sam and The Kid. Chris Marker is interviewing Small Sam about his journey and Charlotte together with The Kid confirms the events.
Charlotte was again seen in the front line of Paddy's troop he called Youngbloods. She turned out to be pretty good in the combat practice.
She went with Shadowman to the abbey to reunite with the other greens.
When Charlotte and Shadowman are headed back home with The Hunters, they encountered a horde of zombies coming from the west and south. She was killed by the horde led by the Medusa in the house where they barricaded themselves.