Why is A selfless in the book Every Day?

In Every Day, the character of A, in some regards, cannot even be considered a person throughout most of the novel. The entity referred to as A lacks a fixed self in every regard, such as gender, race, age, and other markers of identity. Nevertheless, the idea of having a self becomes appealing to A while they are inhabiting Justin’s body; the current person is a cis straight male, and that becomes an important aspect of the identity that A temporarily desires, motivated by Justin’s relationship with a cis straight girl, Rhiannon.
The dawning of individual consciousness in A stimulates a series of complications, however. From the point of realizing the power of this desire, A begins to want a fixed self. David Levithan thus builds a fundamental contradiction into the book: if A is selfless, then the entity that begins to develop a self is no longer A. The further realization that they are not alone in the ability to move between bodies adds to the contradiction: having just begun to figure out that they are unique, A now understands that there is a community to which they belong. A change of setting and the development of conscious interest in having a self are important further steps that A takes toward fulfillment.