|“||Shhh... Miss. Flowers will think I'm a floozie if I have a man in here.||”|
The relationship between Katherine Pierce and Mason Lockwood began at some point during season two. They were first seen at the end of Kill or Be Killed as lovers. When Mason was killed by Damon in Plan B, Katherine was upset because her plan had failed and she could no longer use Mason to get the moonstone. It was clear that Mason loved Katherine but didn't trust her, as he hid the moonstone at the bottom of a well filled with vervain. Katherine obviously did not love him, as she was just using him.
Katherine and Mason's relationship was revealed in Kill or Be Killed at the end of the episode. They kissed passionately in an Aston Martin as Mason told Katherine he had gotten the moonstone. In the following episode, Plan B, Katherine and Mason are seen making out in a bed. He promises to get the moonstone for her, unaware of Katherine's true intentions to hand him over to Klaus to be sacrificed as the werewolf in the ritual. The moonstone is later found in a well full of vervain, and Damon kidnaps Mason and takes him to the Salvatore Boarding House, torturing him for information. Mason reveals enough, and Damon rips Mason's heart out. Katherine later finds out via a phone call, and promises she has a Plan B.