She is dating a vampire named Blake. She and Blake are sent to Mark Lilly's class by court for illegal vampire conversion. Grimes strongly dislikes them dating as his own wife Vera has left him for a vampire, the Count.
When Grimes succumbs to Mad Larry Disease, he is eventually cured by Blake's father, and becomes more tolerant of vampires. Tristan and Blake finally get married. It is revealed at her wedding, when she smiles and shows her new fangs, she has become a vampire.