Mark, also called “Rents” and “Rent Boy,” is the main protagonist and narrates much of the book. He is an intelligent young man, having dropped out of university after getting addicted to heroin—but maintains his interest in “intellectual” topics like theater and philosophy. He’s cognizant that he is a “coffin dodger” and will likely end up dead if his heroin habit continues. He can switch between slang and “proper” British English, as is seen when he goes to a job interview, which he sabotages so that he doesn’t have to work and can keep collecting welfare.

Mark is an unreliable narrator. While he expresses some of the most compelling insights into addiction and its grip, these often arrive while he’s high. In the end, he proves himself to be among the most untrustworthy characters when he steals his friends’ money in order to create a new life for himself. It’s unclear whether he will remain clean or not once he gets to Amsterdam, but Mark seems to be “burning the bridge” with his friends so that he can create a new, clean life.