They were together before Maze, but then WICKED sent Minho to the Maze. It was too hard for Katherine to live without him and she doesn't want to work for WICKED, so she help to Right Arm. Tomas helps her, but one day he betrayed her. She is part of the Right Arm. She is a spy. She was a spy before Thomas betrayed her. WICKED sent her to the maze. What happens after you will see. "Do you remember me?" he asked her "I'm sorry, but I don't know you" Katherine replied.