Nina is one of the shadow children and the main character of Among The Betrayed.
Nina was first introduced in the second book Among The Imposters as a secondary character. She is the leader of the three girls from Harlow that Luke meets in the woods along with other third children as well as Jason (Jackal Boy), whom Nina had fallen in love with but later betrayed her and the other third children.
In the third book, Among The Betrayed, Nina is the main character. She has been imprisoned by the Population Police because she was believed to be Jason's accomplice in turning in children who were proven to be legal citizens. Mr. Talbot, a double agent working against the Population Police, tested Nina's loyalties by placing her in a cell with three other third children, telling her that if she did not find proof that they were third children and turn them in she would be executed. The test was that if she refused to turn them in, she passed the test and would not be executed, but if she did turn them in she would prove herself a threat and be executed. When Nina neither helps nor betrays them, Mr. Talbot lets her escape with Mattias, Percy, and Alia . They travel many days in the woods, and Nina discovers that the other three are smart for their age. Finally, when they reach Mr. Hendricks cottage, she passes the test by telling Mattias, Percy, and Alia that she was supposed to betray them but didn't. This is also the book where we first learn of Nina's past. It is revealed that she used to live with her "Aunties" while she was in hiding, and that her real name was Elodie Luria before she got her fake name Nina Idi. There is a brief notion of her mom coming to visit her occasionally, but there is no mention of the older siblings that made her a third child. In her flashbacks, it is mostly memories of her different aunties; one believing in God, one obsessed with soap operas, and all of them pampering her and calling her their miracle and "Elodie, my melody".
Later, in Among The Enemy, she was a secondary character who signed up as a serving girl at Population Police headquarters and helped Mattias spy on the general as well as foil Jason's plan to get rid of all people with fake IDs. There were other people undercover at Population Police headquarters, but Nina is Mattias's main consultant as she is the one who gave him the bug to spy on the general as well as passing notes as Nina handed him food and climbing through the heat duct to meet with Mattias in the bathroom.
Nina is a secondary character in Among The Free but does not appear until the end when she talks to Luke after his speech and helps tear down the posters discriminating third children with the help of Trey and Mr. Talbot.
In the third book, Among the Betrayed, she is really introduced as a character, showing characteristics of shyness, bravery, and selflessness.
Nina is said to have brownish-blonde hair, usually in braids, and her eyes appear to be green on the cover of Among The Betrayed.