What are the foils for Ethan and Mattie as individual characters, and for Ethan and Mattie as a couple?
Although he does not play a major role in the novel, Denis Eady is introduced in Chapter I and serves as a foil for Ethan. Enis and Ethan are of the same approximate age, but unlike Ethan, Denis is a financial success and as the son of the successful grocery store owner in Starkfield, he appears to be headed for even greater success in business. Furthermore, Denis is very sociable and uninhibited with women to the point of being impudent and wolfish. He is first seen in the novel dancing with Mattie in a way that Ethan finds scandalous to the point of inviting a "horse-whipping." All of Eady's characteristics contrast Ethan's own shyness and poor station in life.
Zeena is the most obvious foil for Mattie. She represents all that Mattie is not. Zeena is an older woman who seems to be an old woman. Plain, querulous, and demanding, Zeena is all darkness to Mattie's light. The stark contrast between them is emphasized through scenic contrast when each woman at separate times stands on the stairs holding a lamp. Zeena appears ugly, sharp, hard, and angular; Mattie is young, soft, and beautiful.
Ned Hale and Ruth Varnum act as foils for Ethan and Mattie as a couple. Ned and Ruth, like Ethan and Mattie, are young and in love. However, theirs is an acceptable relationship with a future. They are engaged and will be married. They have the right to kiss each other, as Ethan and Mattie observe them doing. Their happiness contrasts the unfulfilled longing in Ethan and Mattie's relationship.