Sixteen-year-old Tierney is the main protagonist of The Grace Year. Liggett describes Tierney as being fiercely independent and completely uninterested in the prospect of marriage, positioning her as the primary representative of Rebellion and Resistance to Tradition. Readers quickly learn that Tierney “made damn sure” that she would have “no prospects” on her Veiling Day by fishing, climbing trees, and engaging in other traditionally masculine pastimes (7). Tierney states that she “openly ridicule[s] every boy who show[s] even a glimmer of interest” in her (48-49), and because of her dedication to a life of singledom, Tierney has a hard time making friends with other girls. Tierney knows how to live and survive on her own, but she discovers the importance of love and sisterhood over the course of her grace year.

Tierney values truth over everything else. When the grace year begins, Tierney is determined to “keep a level head” with her feet “firmly rooted in the soil” (91). As the daughter of a doctor, Tierney believes in the power of facts and medicine, which also sets her apart from the girls in her grace year who crave the glamor and mystery of magic.