Throughout the text, the motif of performance helps to articulate the theme of Humanity Versus Monstrosity by illustrating the performative nature of human society and how individuals disguise or alter parts of themselves to fit in. Each character puts on an act to a greater or lesser degree as they try to inhabit the social roles they are expected to play.

At the start of the novel, Magos draws criticism from others because her grief numbs her. Her inability to perform grief in the expected way causes Joseph to assume that she is not affected by the loss. Later in the novel, Magos becomes a performance artist and turns her grief for her son into an actual performance. However, her family also criticizes this public display of grief, illustrating the difficulty and complexity of meeting social expectations.

Oftentimes, characters perform identities in the hope that one day the act will stop or will become so natural that it feels like their true self. As Monstrilio starts to grow, Magos and Joseph move back in together and pretend to be a family again. However, Joseph feels as if they are going through the motions, “[f]aking it until it becomes real” (142). Joseph and Magos eventually divorce, but this ruse of being a family continues as they raise M to replace their dead son. M makes every effort to play along, but much of what Joseph and Magos see as him “getting better” is a performance. M suppresses his hunger and pretends to be human to gain his family’s love and acceptance.

Eventually, M realizes he cannot maintain his human charade. Despite the pressure to conform to social expectations, performing an identity that doesn’t align with one’s true self is ultimately unsustainable.