Penryn is the protagonist and hero of the novel, as well as the first-person narrator. She is characterized as tough, practical, and cynical, despite her constant awareness that the apocalypse has made her this way; she implies throughout that she used to be much kinder and more frivolous, stereotypical of a teenaged girl. Penryn regularly describes herself as plain looking and unkempt, partially due to the rough conditions she lives in, and she is characterized as something of a tomboy, as she dislikes getting dressed up to infiltrate the aerie. Her physical descriptions characterize her as ordinary, but other characters, namely Raffe, tell her that she is beautiful, which emphasizes both his attraction to her and her own difficulty perceiving herself as someone with value.

Penryn’s identity is heavily shaped by her family. She is the guardian and protector of both her mother and sister, who have disabilities, after her father’s departure and the advent of the apocalypse. She loves her sister deeply but has mixed feelings toward her mother, who is frequently unstable and abusive toward her. Penryn can be extremely judgmental of others, however, and prioritizes her own survival over protecting others—with the exception of her sister.