Tatiana is a character from "Camp Fear". She, along with Cindy and Tracy, were Quinn's friends at Camp Grizzly, where they pretty much ignored all the camp activities. In the gang of clones, she's the Tiffany Blum-Deckler.
At the reunion, Quinn was hoping she could get a ride home with Tracy's crew. That plan was wrecked when she accidentally revealed she'd stolen Tracy's boyfriend at camp. The girls abandoned her, with Tatiana the only one apologetic about it.