Trina is a high school student and manages to maintain a good image with a relatively large group of friends. She is good at field hockey, and she wants to be at the center of attention. She has a crush on Sam, but Sam dislikes and actively ignores her. She has a disdain for the Fitzgerald sisters.
Trina first becomes hostile to the Fitzgerald sisters after overhearing from her friend that Brigitte was making fun of her while the sisters were playing "Search and Destroy." Further, she become even angrier at Ginger when she kicked Morley, Trina's dog, for snarling at her. After both situations, Trina took her frustration out on them in the form of pushing Brigitte to the ground on the field hockey field. The first time, Brigitte fell into a dead dog's carcass. The second time, Ginger no long stood by idly and flew into a rage and pounced on Trina, brutally pummeling her in the face until the gym coach Ms. Sykes was able to separate them.
Later, Trina's dog turned up missing. Trina went to the Fitzgerald's house, found Brigitte returning home from Sam's, and accusing Brigitte and Ginger of stealing her dog. As it was, Ginger killed Morley, but Trina did not know this.1
Ginger suddenly appears and grabs Trina in a headlock, dragging her inside the house. Brigitte tried to get her sister to stop, but Ginger kept torturing Trina until Trina came up with a plan to get her to let go. She stuck Ginger's fingers into her throat and induced herself to vomit, forcing Ginger to let go. Trina managed to scoop up a steak knife and wave it in front of the sisters, forcing them back. As she walked towards them, she slipped in a puddle of spilled milk and fell backwards, slamming her head against the corner of the counter-top, causing a fatal blow. Ginger and Brigitte hid Trina's body inside a freezer, but were later forced to relocate it. While trying to remove it, the sisters discover her body frozen stiff. While moving, Brigitte accidentally broke off two of Trina's frozen fingers. They extradited the rest of the body from the ice and buried it in the backyard toolshed.
The next day, her father placed missing persons' posters all over the town and school. The sisters found out about this and decided to lay low until the events passed.
Trina is depicted with golden hair and wears a t-shirt. She is seen walking Morley, her dog, and attempts to grab Sam's attention.
"She's your standard, cumbuckety slut"Brigitte on Trina
Trina is the primary antagonist to the Fitzgerald sisters. After her accidental death, the tension switches to the sisters laying low and not attracting police attention, but Ginger's lycanthropy transformation threatens to expose them and makes "living a normal life" difficult.
Trina also represents a hint of irony when she unsuccessfully tries to court Sam but fails to grab her attention. However, quiet Brigitte manages to speak to him, causing jealousy for Trina and further making her bully Brigitte. Ironically, Trina is also the source of jealousy of Brigitte and Ginger, who may not directly show it. They express hatred of her self-promotion and admonish how she probably makes out with several guys, but this may stem from their desire to be accepted like Trina is by her friends.
- In a deleted scene, Pamela Fitzgerald, the Fitzgerald's mother, presents the fingers in a plastic box to get them to arrest her so they wouldn't detain the sister, as what Pamela thought.
- The character of Trina Sinclair was created by director and screenwriter John Fawcett as well as Karen Walton.
- It is unknown when she started bullying the Fitzgerald sisters, but she actively did so after she overheard Brigitte making fun of her.