|“||Dark magic formed us from animal, bronze, and ghost! We exist to feed on the blood of young men. Now come, give me that kiss!||”|
Percy Jackson first meets Tammi and Kelli when he was trying to get into the Goode High School via the back exit trying to avoid Rachel Elizabeth Dare. Tammi was going to try and kill Percy right then, but the arrival of Paul Blofis stopped them. Later they tried to kill Jackson, trapping him in a room with musical instruments with the mortal, Rachel Elizabeth Dare. First, Tammi moved in a way that enchanted Percy. According to him, her eyes and the way her hair swept over her shoulders made him dazed. Tammi came close, but Rachel snapped Percy out of the seduced state he was in, but Tammi offered a kiss. Fortunately, Percy did not fall under her spell again and he was able to kill her, but not Kelli, who was much more experienced than Tammi. She is said to be Kelli's trainee.
While pretending to be a normal cheerleader, Tammi is a valley and alluring girl, but, in her true form she's violent and provoking.
Tammi is described as "hot" and having blond hair and "icy blue eyes" when covered by Mist. She is shown to be an attractive woman since Percy was dazed at the way her hair swept over her shoulders and by her icy blue eyes. In her real state, her skin is pale white, with red eyes, fangs, and flaming hair. One of her legs is a donkey leg and the other is bronze.
- Seduction: As an Empousa, she can put men under her spell so she can feast on their blood.
- Charmspeak: As an Empousa, she can charmspeak in order to attract her mortal victims.
- Shapeshifting: As an Empousa, she can change from her human form to their true form.
- Mist Manipulation: As an Empousa, she can manipulate the Mist.