This is the first time I see Shinji's father give emotion to a child, Rei and that is kinda fucked up. I don't know what happened between the two but Rei seems to only get along with Shinji's dad and acts like an asshole to Shinji. This also shocked Shinji because he has never seen or heard of his father doing that for him or anyone else. Shinji's dad was pressing Shinji to go out there and fight another Angel whereas he let Rei stay inside after the activation with her Unit 00 was complete. Almost like Shinji's dad wants to replace his son with Rei, the daughter he never had. This Rei girl is weird, she also seems very robotic like Shinji in the first 3 episodes and I just realized that the operators are all children. I don't know if it's symbolic for children are the future of humanity or it's just easier to manipulate children than it is for adults.