When Rhys makes the bargain with Feyre Under the Mountain, the process leaves a mark: a blue-black tattoo on her left arm with an eye on the palm of her hand. Initially, Feyre sees the bond as a necessary sacrifice to save the lives of Tamlin and his court. As her relationship with Rhys grows more intimate, however, the bond—and its visual signifier, the tattoo—take on a deeper meaning. As she and Rhys share their thoughts and fears telepathically, the eye symbolizes their ability to see into each other’s minds, and their willingness to stand naked (physically and emotionally) before one another. When the King of Hybern breaks the bond, the tattoo shrinks. The king has broken the visitation contract, but he cannot break the bond of mating, a connection deeper than any magic. Rhys has become physically imprinted on Feyre, a symbol of their inextricable natures.

Feyre frequently paints in red or imagines red in her art. Red represents anger, courage, love, and war—the common thread of which is passion. Feyre is at her lowest ebb when she cannot express that passion, when Tamlin keeps her sequestered in his manor. A fire burns inside her—her dormant faerie power—and its only outlet is physical expression, be it painting, sex, or battle.