T.J. McAllister is the bass player in Schroedinger's Cat, Cooper's first band. They start dating in Second Sight. He is very supportive of her Wiccan studies, and Cooper becomes very close with the rest of his family as well. Despite Cooper leaving the band in Through the Veil, their personal relationship is the most stable of the entire series. However, they understand that with college on the horizon, the future of the relationship is uncertain.