Ayanami Rei is the “First Children” of the Marduk Report and the pilot of EVA-00. Shrouded in mystery, she is socially withdrawn and rarely shows emotion. Seemingly completely devoted to her duty as an EVA pilot, her only apparent human relationship being with Nerv commander Ikari Gendou.
However, Rei comes to know Ikari Shinji and after some initial mistrust they come to better understand each other, revealing more of Rei`s emotional side and helping Shinji trust others again.
It is eventually revealed that Rei is not a normal human, but an Angel - Lilith. Soulless clones of her are kept hidden in the deepest levels of NERV, to be used both as replacement bodies for Rei should she die and as “cores” of the Dummy Plugs. Gendou, knowing of Rei’s true identity, plans to make Rei help him control Instrumentality to reunite him with his wife.