Nancy was the first known victim of Percy Jackson's demigod powers. According to the book, the water from a nearby fountain "reached out and grabbed her" on a school field trip in Manhattan when she bullied Grover and angered Percy. However, she simply claimed Percy "pushed" her, knowing he would get into trouble for it. That was when Alecto's (who was posing as Mrs. Dodds) suspicions were confirmed that Percy was a half-blood or (more specifically) the demigod son of the sea god, Poseidon.
She is later mentioned by Percy remembering all the persons that ridiculized him in all his life, also including Clarisse La Rue and other classmates of the schools that Jackson attended.
She is described as being a kleptomaniac (someone who has an addiction to stealing). Percy hated her because she was always teasing Grover Underwood such as throwing pieces of food at him (like her peanut butter and ketchup sandwich). Percy couldn't resist trying to "fix her up," but was blamed in the graphic novel that he pushed her in a fountain of water. She was Mrs. Dodds' teacher's pet, allowing her to get away with anything, including her bullying and pick pocketing.
Nancy is described as a girl with curly red hair, orange freckles, which Percy describes "looks like they were sprayed on with liquid Cheetos" and crooked teeth. Percy said that Clarisse La Rue reminded him of Nancy, but Clarisse was stronger looking and much bigger.
- The part of her name "Bobo" is probably based on the same word in Portuguese which means "stupid" to fit her personality.
- In the film adaptation of The Lightning Thief, she is Asian and doesn't bully Percy. The closest she comes to bullying is calling Grover a perv for taking pictures of Aphrodite's bust (this is a deleted scene, however).
- Percy was originally supposed to stumble upon Nancy Bobofit in The Last Olympian but the part was cut because the book was getting too long. The scene would have involved Annabeth, Grover, and Percy finding her and the rest of his class from Yancy asleep in the middle of the New York park. They would move them to a safe spot.