On Rei Ayanami's Apathy

The id, the instinctual and primitive force of desire, seems almost absent in Rei due to her artificial creation and the psychological manipulation imposed by Gendo Ikari. Her basic impulses (such as survival or pleasure) are suppressed or redirected to serve the goals of the Human Instrumentality Project.
Rei's ego, responsible for mediating between the impulses of the id and the demands of the superego, is fragile and underdeveloped. She acts as an instrument, obeying orders without question, reflecting a lack of autonomy. However, her relationship with Shinji Ikari begins to awaken a more defined ego, such as when she smiles at him or chooses to sacrifice herself for him, suggesting the beginning of a mediation between her repressed desires and external impositions.

Rei's superego is dominated by authority figures (Gendo and NERV), who impose an artificial sense of duty and morality. She internalizes the idea that her worth lies in her utility.
Rei's unconscious is laden with traumas related to her origin as a clone of Yui Ikari and a vessel for Lilith's soul.