The older daughter of Silas and Persis has a sense of humor which is not literary, coming in flashes and ripples, but rather droll and commonplace. She is plain but not practical like Irene. Instead, as her mother points out, she is a dreamer with twice as many brains as Irene. Her character is set at the beginning of the novel and does not change even after her love affair with Tom Corey.
Penelope represents the witty but plain romantic woman. Like the heroines in popular contemporary novels, she is confronted with the problem of having the man believed to love her sister really in love with her. Also, like these heroines, she attempts to give up the lover in a passionate outburst of self-sacrifice. Reality and the pressure of her realistic father and Tom Corey help force her to marry him, but it is more her romantic burst of passion for him that makes her say, "Yes."
The marriage does not immediately advance her position in society, for she and Tom go to Mexico to live and work after their marriage. One of Tom's sisters says, "As she's quite unformed, socially, there is a chance that she will form herself on the Spanish manner, if she stays there long enough, and that when she comes back she will have the charm of, not olives, perhaps, but tortillas, whatever they are: something strange and foreign, even if it's borrowed."