The story's primary setting is the Paris Opera House, so music is a key motif within the narrative. Music has various functions throughout the text, and one of its uses is foreshadowing. Leroux, an Opera critic in his own lifetime, alludes to many well-known operas whose plots mirror the events of The Phantom of the Opera; therefore, those who recognize these operas will have extra knowledge of where the story's plot is heading and the dynamics between different characters. Some of the main operas that Leroux alludes to include Romeo and Juliette and Othello. These pieces help explain the changing relationship between Christine and Erik. Romeo and Juliette is a classic story about lovers who don't know each other’s identities, which allows them to fall in love without bias. However, when they find out they are from rival families, their relationship becomes complicated and ends in tragedy. In Chapter 2 when the text first references this opera, Christine doesn't know Erik's identity, which allows her to develop a relationship with him as the benevolent Angel of Music. When she uncovers the truth, however, his obsession quickly leads to near-tragedy for her and Raoul.