When Rodolpho tells Catherine that he can sing, she asks him to sing the song “Paper Doll” for her. He ends up singing the song repeatedly throughout the play, and apparently sings it so much while working that he earns the nickname Paper Doll. As a popular song, “Paper Doll” is something that the young Rodolpho and Catherine share together, and which Eddie is therefore jealous of. He is irritated when they dance together to the song near the end of Act One, as bonding together over the song has drawn Rodolpho and Catherine closer together. In addition, the title and lyrics of the song are symbolically significant. The idea of the paper doll is important as Rodolpho’s nickname because of its connotations of fragility. The nickname is a result of Rodolpho’s odd behavior on the docks, including singing in a high voice, and makes Eddie uncomfortable because it suggests that Rodolpho is effeminate, and potentially not heterosexual. In terms of lyrics, the song says, “I’m gonna buy a paper doll that I can call my own, a doll that other fellows cannot steal.” The idea of having a woman completely under one’s control and in one’s possession, like a paper doll, is eerily similar to Eddie’s ideal relationship with Catherine. His love for her is so possessive and oppressive that he treats her more like a doll he wants to control than a family member.