While content with her life on the Rock, Tress collects cups that sailors bring from around her world. Although Tress asserts that she would be content living on the Rock, the cups represent a fascination with the outside world. Tress loves finding out more about the cups’ origins, and her love for the cups and their stories symbolizes the love of adventure and travel that Tress realizes only through her reluctant adventuring.

The cups play multiple roles in the narrative. Charlie sends them to Tress as signs that he is successful in driving away each princess he meets; in this role, the cups represent the couple’s love and their determination not to let the world pull them apart. By the end of the novel, the cups also come to represent the couple’s growth and change through their journeys. Tress tells Charlie of the two cups she had with her when seeing the Sorceress: “I love them. Particularly the one with the butterfly on the sea. Like us, Charlie. Soaring over places we never thought to go. And the one made of pewter. Like us, Charlie. Stronger and more straight-forward than we have a right to be” (445).