J. J. is pale, beautiful, and slender, and has the honed muscles of a professional ballet dancer. She has spring-blue eyes with long, straight, blond hair, and a distinct resemblance to Jason, the two having the same Great-Great-Grandfather.
She first appears in Blood Noir , when she returns home to be a bridesmaid for her friend Lisa. At the bachelorette party J. J. reconnects with Jason and the two start to visit each other as often as they can, although at first she flirts more with Anita.
In Bullet, she visits St. Louis for the third time in as many months, this time to watch Jason dance during a small recital of the local dance school. Jason has likewise made three trips to New York to see her onstage with the New York City Ballet. JJ also takes part in the orgy induced by the ardeur. She becomes temporarily attracted to Bianca, one of the local swanmanes, but JJ recovers and continues her relationship with Jason.
In Jason we see more of J.J., when she comes to St. Louis to learn what Jason means with rough sex, and to help Anita with her issues in dating Jade. At first J.J. is intimidated by what Jason and Anita get up to together, knowing that it's something J.J. will never be able to offer to Jason, but is eventually reassured that it's something Jason needs every now and then in addition to what he has with J.J., not something he wants all the time.
J.J. and Anita both learn a lot during the two evenings the book covers, and it turns out that J.J., Jason, Anita, and Nathaniel have a lot of fun in bed together, much more so than J.J.'s had in a long time with her live-in girlfriend Freda. In the end J.J. decides to break things off with Freda, although she'd prefer that Freda does the actual leaving, because it's a pain to find an apartment in New York.
We also learn that J.J. is talking to her dance company about Jason trying out, even if it's an all-human company and no lycanthrope has ever been allowed to one of those yet.
During Dead Ice Jason is visiting J.J. in turn, so we don't see either of them in person.