Cool and laid-back, Mark is the complete opposite of his wife. He also shares same interests as Juno: they both love punk rock and horror movies. However, despite his dreams of furthering his musical career, he now composes commercial jingles. Unfortunately, after having an emotional interaction between him and Juno that was too close to comfort, Mark decides to leave Vanessa and that he is not ready to be a father, much to the dismay of his wife and Juno, whom he asked, "How do you think of me?".