These are reasons from every Evangelion episode and movie. Most of the information isn’t in order. I really hae to go back and fix that, but you can deal with it for now . . .
1) Rei appears as a mirage in the the beginning. This could have many meanings, like it tell us what kind of person Shinji is. When Shinji met Rei in front of Eva Unit 01 later in the show, he looked at her, as if he’d seen her before. De ja vu = love, and I don’t think they put that there for no readon. (Borrowed from Ryan Xavier’s Shinji/Rei site)
2) Shinji pilots Evangelion Unit 01 (who has rejected everyone up to now) and uses it to fight the Third Angel just so Rei won’t pilot it and get destroyed. We can call Rei the damsel in distress in this scene.
1) We only see Rei one in this episode, and that’s when she’s on a stretcher. She merely gazes at Shinji, and Shinji gazes back. We all know Rei is a thinking person, questioning her feelings. She could be contemplating why this boy decided to pilot Unit 01 just so she wouldn’t die. Remember, she is “expendable”.
1) Shinji notices that Rei is always alone. He wonders why, and continues to think about this “girl who has no friends”.
2) He gropes over her. Accident or no accident, it’s undeniably intamacy.
1) Shinji burns his hands and leaves permenant marks on them while trying to pull Rei out of the entry plug. After he sees Rei is alright, he breaks down in tears. I don’t remember him doing so for anyone else.
2) Rei smiles for Shinji. The firt time in her fourteen years of life she does so for another person. (Gendou doesn’t count, he was a parent figure)
1) Shinji and Asuka have been living in the same apartment, yet Shinji and Rei pull off a perfect synch during the synch training. Many people have said this is because Yui Ikari’s soul is within Rei. Wrong. Yui’s soul is within Unit 01. The perfect synch between the two could be a sign . . .
1) As the Eva Pilots are going to Nerv, and when the pilots are climbing the vents, Rei’s eyes go to Shinji. Unusual for Rei, since she is always looking forward.
1) Rei usually doesn’t speak or answer questions. She answers Shinji’s question, while ignoring Asuka’s. Okay, she hates Asuka, but still, Rei was raised a lot like some sort of young soldier where she would answer her superiors. Most likely, she would answer one of her colleagues, but she doesn’t.
2) We’ve seen up to now that Asuka likes to insult people. She needs to be noticed and other people to see that she’s “there”. However, Shinji admits he doesn’t like being around people. This is possibly because he doesn’t like expressing his feelings often. This is very similar to Rei’s personality, but totally opposite of Asuka’s personality. People with common personalities attract each other while peopl with opposite personalities usually reject each other. Remember, Eva is much more realistic anime in terms of human relations.
1) While synching with Unit-01, when asked how it feels, Rei says that “it smells of Ikari.” Okay, why is the girl who uses a bunch of techinical words say “it smells of Ikari”?.
1) Shinji overcomes his intevoerted-ness to talk to Rei. He hardly sparks a conversation, and when he does, he did with the girl who NO ONE talks to. Rei responds as well. Pretty much passes for a “heavily introverted person’s” conversation.
2) Shinji tells Rei that she’s make a good mother one day. It’s been a sign that a Japanese boy saying that to a girl means he has interest in her. Plus, she blushes at the comment. And to top it all off, she says that Shinji is embarrasing her. How often do you think Rei is embarrased? How often do you think the ice queen blushes?
3) Shinji is nervous about meeting with his father. Yet, he calls out to his father after deriving some courage from Rei.
4) Shinji is worried when Rei is absent from school.
1) Everyone is worried when Shinji is getting absorbed by the Angel. Unusually, Rei shows feeling because she is worried as well.
2) Rei refuses to retreat and abandon Shinji during a sortie. Misato is forced to repeat herself before she retreats.
3) Rei usually minds her own business. She actually pays attention to Shinji and Asuka’s conversation. When Asuka begins to insult Shinji, Rei is annoyed. While Asuka continues to insult Shinji, Rei takes it upon herself to stop her. She actaully takes an independent action for Shinji.
4) When Shinji awakens in the sick room, Rei is there, waiting for him. She tells him to rest, and compliments him. Note: I’m sick and tired of Shinji-Asuka fans stating that Rei said the same words Yui told Shinji, “That is good for you”. Remember, Rei was shaped by Gendou, so he could have taught her to compliment like that since Rei is his key back to Yui.
1) Shinji cleans Rei’s apartment, even after Touji tells him not to.
2) Rei blushes after he does so. Plus, she says thank you. The very first time in her life she’s ever used those words. And to of all people, she says “thank you” to Shinji.
1) Rei actaully confronts Touji, one of Shinji’s friends. Touji guesses that she’s looking for Shinji, she agrees. Touji also states that Rei really does care about Shinji, which she also agrees to. Note: Touji has made remarks toward Shinji and Asuka. However, those were jokes, just to get a laugh out of the class. Touji was 100% serious toward Rei’s comment.
2) Rei informs Shinji what happened in the test facility. She tells this wuss instead someone more qualified. It’s evident that she trusts and respects Shinji.
1) The first few words we here from Rei are, “How is Ikari”. She’s definetely worried about Shinji.
2) While Shinji is thinking, Rei crosses his mind. He finds that Rei is someone who comforts him.
1) Rei continues to ask herself, “Does my soul wish to be one with Ikari’s?”. Note: Many people have claimed that before Rei dies, right after she asks herself “Does my soul wish to be one with Ikari’s” that she says “. . . no.” Complete BS. I watched both the subbed and dubbed versions of this episode looking for that. I paused the tape hundreds of times to see even if there was mere mouth movement of the word “No” and I saw nothing.
2) Rei blows herself up just so that Angel won’t attack Shinji. Remember, Rei wasn’t ordered to self-destruct, she was ordered to retreat. However, once it became appearant that Shinji was in danger, she blew herself up, destroying the Angel.
3) Rei’s last words are, “My soul wishes to be one with Ikari’s”. For those who don’t know what that means, it has three meanings. First, is that the soul can’t livei n loneliness forever. Second, Rei wishes to be with Ikari. She loves him. The Third and final meaning is that she wants to have intercourse with Shinji. Enough said.
(Let me quickly note the End of Evangelion does not take place after Episodes 25 and 26. The Televised Ending and the End of Evangelion both take place after Episode 24. They are alternate endings, though Anno and GAINAX have stated that the TV Ending is the real ending)
Neon Genesis Evangelion Ending I: Televised Ending, Episodes 25 & 26:
1) One of Rei’s lines are, “even though he was as human as me?” She compared herself to Kaworu, stating that even if she was part Angel, like Nagisa, she loved Shinji.
2) Rei is the only person who doesn’t say she hates Shinji.
3) Rei helps Shinji, by telling him that no one sees the real Shinji. In fact, they refuse to. Rei wouldn’t know this unless she saw the real Shinji. She also says, “You cannot see youself unless others are there”. She may be stating Shinji needs people to be around him, but she could also be stating that she wants to be near him.
4) Rei out of all people lectures Shinji on love. She says, “If you truly hate yourself, you can never love, and can never place your trust in another.” (In some translations, she says “Those who hate themselves cannot love or trust others.” It’s all the same)
5) Throughout Episodes 25 and 26, Rei has attempted to guide Shinji. Shinji was Rei’s guide throughout the series. They were each other’s guides, and evidently, soul mates.
Neon Genesis Evangelion Ending II: Movie Ending, Episodes 25 & 26:
(Note: Many say this movie is all about Shinji/Asuka, and it is pretty convincing. But, Ryan Xavier’s reasons, sounding very convincing as well, were borrowd for reasons 1 and 2.)
1) Rei leaves Gendou in favor of Shinji.
2) Look at how the are positioned after the Third Impact.
3) Rei guides Shinji, by telling him the hardships of growing up.
4) Though Shinji rejects Third Impact, he didn’t kill off Rei. She, too, went to the Sea of LCL. Remember, Rei was supposed to disapear after Third Impact. However, Shinji was in control, not Gendou, so Yui didn’t return, which would have caused Rei to vanish. Shinji not bringing his mother back but letting Rei’s soul live on had to mean something.
5) By rejecting Third Impact, Shinji makes it so that man can return to their individual form. Remember, man can return from the Sea of LCL if they are willing to. Shinji returned because he was in control of the Third Impact. Asuka probably returned because she is a very independent person. For all we know, Rei could return two minutes later.
Note: It is possible that in the TV Ending, Rei was Shinji’s soul mate, while in the Movei Ending, Asuka was Shinji’s soul mate. Believe what you want, i’m a Shinji-Rei fan.