John Paul Reynolds Abernathy IV or J.P., as Mia and her friends like to call him, was known as The Guy Who Hates It When They Put Corn In The Chili (before the seventh book). He got this name when people started noticing that his hobby included taking out the corn from the chili the cafeteria ladies served. He was a loner and considered transferring to Florida (as he put it in his play "A Prince Among Men..." in the tenth installment). He became friends with Mia after her grandmother put her in a musical in which he was cast in asvthe lead. He was described as "cute" by Lilly and Tina and Mia agree that he is cute in a big, teddy-bearish sort of way. He dated Lilly for six months and broke up with her as soon as Mia broke up with Michael. According to Mia, he smells like dry cleaning fluid, unlike Michael. She tries to love him, but she can't. His favorite celebrity is David Manet and then Sean Penn.

In the tenth book, it was revealed that J.P had lied to Mia about his breakup with Lilly. Mia then realizes that J.P. had only been using her as means to get into the spotlight. After Mia dumped him, she suggested him to "call Stacey Cheeseman. I think she has a total crush on you". The day after, it is shown that J.P. and Stacey are dating, but Stacey was seen 'making out with Andrew Lowenstein' by Tina Hakim Baba.

According to his father, Mr. Reynolds-Abernathy the Third, J.P. had been eating lunch alone ever since he started at "that snobby school" (meaning Albert Einstein High School).