A.J. is one of Timmy's two best friends. A.J. is smart and rich, but is not very good at social skills and as a result he is considered an unpopular kid like his two friends.
He is the only student that seems to ever pass tests in Mr. Crocker's class. He mostly wins the school science fair as well, even when up against Timmy and his fairies, because fairies cannot help win competitions. A.J.'s family is very wealthy and they live in a big house, which is located near Chester's trailer.
He is bald, and wears a light blue sweater vest, which is describe as a "girl magnet", over a white shirt. He also has grey pants with black shoes. His pupils are colored blue. A.J. is around the same height as Chester and Timmy.
A.J. is much smarter than any other student, and this sometimes causes friction between him and his less intelligent friends, as he often flaunts his intelligence to the point of arrogance. A.J. is a fan of Crimson Chin and Crash Nebula, although he seems to prefer Crash Nebula more and sometimes argues with Chester over who is better. He has a secret lab in his bedroom which he uses to create clones, inventions, and conduct scientific research. A.J. is so intelligent that the government has sought him out for his technical assistance. It has also been seen that he can make anything out of anything, A.J. is shown to be attracted to multiple girls such as Trixie Tang, Veronica, and Cindy Vortex.