Theory and Analysis:Rei and the Moon
Throughout the series, Rei Ayanami is associated with the recurring visual motif of the Moon. In fact, the Moon is rarely shown in Neon Genesis Evangelion without Rei in the foreground. Exceptions would be the shots of the Spear of Longinus heading towards the Moon, and the "Moon's eye view" of Second Impact from Episode 21.
For example, in Episode 06 Rei stands silhouetted against the Moon before the mission starts. Later, in Episode 10, Rei is swimming in the Nerv gym's pool: the "camera" views her from below, passing in front of a ceiling light, visually similar to passing in front of the Moon.
Rei's left eye is specifically associated with the Moon. In Rei's monologue in Episode 14, this relation is brought up symbolically by a cut of Rei's eye blinking, followed by a cut to the moon.
In Rei's first scene in The End of Evangelion, she wakes up in the middle of the night with moonlight beaming across her, gazes at the Moon out the window, then apparently realizes the time for Third Impact is coming close and leaves for Terminal Dogma (see below).
Rei is a "vessel" for the soul of Lilith, and during First Impact 4 billion years ago, the Black Moon transporting Lilith collided with Earth, and Earth's Moon formed from the resulting debris. Thus, in a sense, Rei (or the soul of Lilith she carries) actually created the Moon.
The white giant in Terminal Dogma, who we later learn is, in fact, Lilith, wears a mask with crater-like markings. This serves to associate her with the Moon, and thus with Rei.
The moonlit Rei awakens in EOE...
...She has a busy day ahead of her.
Notes
- The visual motif pairing Rei and the Moon is very strong and frequently recurring throughout the series, and due to Rei's connection to Lilith it is actually thematically important. To a lesser extent there is also a visual motif pairing Asuka with the Sun: the first shot introducing Asuka has her silhouetted against the Sun, and in Eva-02's dying moments in The End of Evangelion, Asuka reaches upwards towards the MP Evas, with the Sun behind them. The "Asuka and the Sun" motif isn't used nearly as frequently as the pairing of Rei and the Moon. However, beyond representing Asuka's fiery personality and being a further illustration of Asuka and Rei being polar opposites, its significance is rather simple in the continued dichotomy of Rei/Asuka. The thematic significance is this happens to be choice Shinji faces in End of Evangelion (staying with Rei/Lilith, or returning to reality with Asuka).