Theory and Analysis:Eva-00's Soul

Ritsuko reveals in Episode 23 that, necessary to function, all Evangelions contain a human soul, and it is heavily implied throughout the series and explicitly stated in the Classified Information that that soul must be the pilot's mother. Eva-01 contains the soul of Shinji's mother Yui Ikari, and Eva-02 contains at least the maternal part of Asuka's mother Kyoko. It is implied that all of the other potential Eva pilots in Class 2-A have dead mothers and, likewise, that Toji Suzuhara's mother is dead. Thus, when Toji becomes the pilot of Eva-03, it is implied that it contains his mother's soul. However, Rei was created from the Angel Lilith and the remains of Yui Ikari, and thus does not have a mother. The identity of the soul contained within Eva-00's core is never directly stated in the series, however, evidence and clues as to the identity of the soul in Eva-00 appear several times during the series, particularly in Episode 05, Episode 14, Episode 23 and Episode 25 and also Episode 24.

The Evidence

Rei's Eva-00 was the first working Prototype out of a very long string of failures; it goes out of control twice and is "buggy", often returning errors when under testing. As stated above, Rei has no mother, so unlike Shinji and Asuka, her mother's soul cannot be in her Eva. Aside from the construction defects, the soul inside Eva-00 not being Rei's mother is the likely explanation as to why Rei's Eva does not always function properly.

Episode 5

During a startup test, Eva-00 goes berserk.

Unit-00 punches the window.

• While berserk, Eva-00 repeatedly punches a glass window behind which Gendo Ikari is standing. Ritsuko is further behind the glass but in plain sight of the Eva.
• Eva-00 rejects Rei, and in the process Rei gets severely injured when her Entry Plug auto-ejects.
• When Misato Katsuragi directly asks Dr. Ritsuko Akagi why Eva-00 lost control, the following exchange takes place:

Misato: So, what caused the accident during the last experiment?
Ritsuko: We still don't know. However, we believe that mental instability on the part of the pilot was a primary cause.
Misato: Mental instability? In Rei?
Ritsuko: Yes, her mind became much more disturbed than we had anticipated.
Misato: So what happened?
Ritsuko: I don't know. But it could be...
Misato: Did something occur to you?
Ritsuko: No. That can't be it.

Episode 14

Distorted Rei seen by Shinji inside Eva-00. (Click to see animation.)

A unit interchangeability test is conducted to see if Shinji can synchronize with Eva-00 and if Rei can synchronise with Eva-01 so Nerv can implement their plan for the Dummy Plug. During this test Eva-00 goes berserk.

• As soon as Shinji is connected via the A-10 nerve to Eva-00 he sees a rapid burst of images of Rei. Shinji says:

Shinji: What is this? Something's trying to get directly into my brain. Ayanami? Rei Ayanami? This impression is Rei Ayanami, isn't it? Ayanami? Isn't it her?

When this Rei reappears in Ep. 25, she is explicitly identified in the script as Rei 1.

• Eva-00 goes berserk, and repeatedly punches a glass window behind which Rei is standing. Misato speculates "could it be that Unit-00 just tried to kill Rei?", but after Misato finishes talking to Ritsuko, Ritsuko thinks to herself: "The person Unit-00 wanted to hit was me. I'm sure of it." Ritsuko is in a position to know what soul is where; Misato is not.
• Eva-00 seems to mistake Ritsuko for her mother Naoko; In the "Eva point-of-view" shots Eva-00 sees Ritsuko with Naoko's dark hair. It is unlikely that this is just an animation error because the other details of Ritsuko's appearance and clothing are accurate, such as her unbuttoned lab coat and blue shirt.

Possible Eva-00 targets.	Observe Ritsuko's hair color.	Note the details in both images. Blue shirt, open lab coat.

Episode 23

Armisael speaks with Rei during Episode 23.

• The Angel Armisael begins to merge with Eva-00 and makes direct contact with Rei's mind. When Rei first feels Armisael contacting her mind, she thinks to herself: "Who's there? Me? The me inside the Eva? No, I can sense that there's someone other than me." This reinforces the evidence from Ep. 14 that Eva-00's soul is somehow connected to Rei.

Episode 24

• This episode is important for our understanding of the synchronisation process between Rei and Eva-00. Kaworu is the only other example of a Seed of Life's soul present in a Lilin vessel besides Rei who pilots an Eva. Kaworu synchronises with Eva-02 without its core being reconfigured and later pilots Eva-02 while not present in the Entry Plug. The reason for this is that Kaworu is made of the same matter as Eva-02.

I don't need no entry plug!

Kaworu: The Eva are made of the same body as I am. Because I am born from Adam as well. I could merge with them, if only they didn't have souls. Unit-02's soul has shut itself away for now.

• Rei is made of the same matter as Eva-01 which was grown from Lilith, but not Eva-00. This suggests that Rei successfully synched with Eva-01 in Ep. 14 only because Yui allowed it. Yui has not shut herself away, and successfully rejects synching with Rei in Ep. 19.

Episode 25

The wide-eyed Rei in Episode 25.

• During Rei's experience of Instrumentality she sees a vision of the same wide-eyed "Rei" that Shinji saw in episode 14 when he was in Eva-00. The script for episode 25 explicitly identifies this Rei as Rei 1.

Supplemental evidence

• The Classified Information files that were included with the Neon Genesis Evangelion 2 videogame state:

"A unit called a core is used to eliminate the discrepancies in Eva, a human being with the body of a god and a soul. The soul of the pilot's mother, which is placed within the core, acts as a medium and makes piloting possible... Due to difficulties encountered in the development of Eva-00, the core's system is poorly constructed, and she falls behind in performance capacity as a result. Another reason for her inferiority is that Eva-00's pilot, Rei, does not have a mother."

Also, in an interview with Sadamoto in Der Mond, Sadamoto outright says "the dead mother is inside the robot, which is operated by mental/psychical bonding with the child").

Rei 1 speaking with Rei 2 during the Leliel battle.

• In the actual Neon Genesis Evangelion 2 PSP port video game (which Anno also worked on), when whichever pilot being played as is about to break free from Leliel, the soul of the Eva contacts the pilot. In the case of Shinji, Asuka, and Toji, they see their mothers, while Kaworu is able to force Eva-04 out of Leliel. However, Rei 2 sees the distorted Rei visage shown in Episode 14 (considered to be a hint of Rei 1 being inside Eva-00) and Episode 25 and is designed with "????" as she speaks to Rei.

Rei 1 designated as ???, tells Rei 2 that she must "Retrieve the Fruit of Life from Adam" during the Leliel battle.

Analysis

Eva-00 could have been aiming for Gendo Ikari, Ritsuko Akagi, or its own pilot Rei Ayanami, during either berserk incident. Based on Ritsuko's comment as she trailed off in Episode 05, Ritsuko knows more about the situation than she is telling Misato and there is something of importance which she considers before dismissing as impossible. As Nerv's head scientist, Ritsuko must herself know whose soul is in Eva-00, and she herself stated that all Evas have a human soul inside them. She knows that Rei is just one of a series of clones and possibly knows about the fate of Rei 1 as well.

Eva-00 also seemed to violently reject Shinji, although this may not have been because of Shinji specifically, but rather because someone other than her normal pilot was trying to synch with her. Shinji sees an "impression" of what he thinks is Rei while synchronized with Eva-00, but ends by saying "...isn't it her?", hinting that the "impression" he sees isn't the "Rei" he knows. Rei similarly speaks of "the me inside the Eva".

What does all this mean? There have been many theories over time, but of the three most popular, two have generally fallen into disfavor after many years of sometimes contentious debate. We will address those two first.

Formerly Popular Theories

Eva-00 Has no Soul?

It has been theorized that Eva-00 simply has no soul at all, and that Rei's status as a vessel for the soul of Lilith exempts her from the ordinary rules of synchronization. This would be analogeous to Kaworu, who is a vessel for the soul of Adam, synchronizing with Eva-02 during episode 24 without it's core being reconfigured. Kaworu pilots Eva-02 while not even in the Entry Plug later in the same episode. Others have suggested that Rei had "projected" an impression of her own soul into the core in order to synch, and this is what Shinji encounters in Ep. 14.

However, Ritsuko seems clear in Episode 23 that an Evangelion requires a human soul to function, and she said that each Eva contains a human soul. Also, the Evas came from Adam, not from Lilith.

Proponents of the No Soul theory occasionally object that Both Rei 1 and Naoko were dead, so neither of their souls could have been used. However, it is well established in the series that souls can be salvaged out of dead bodies and placed in new vessels. Rei 2's soul was transferred to Rei 3 the same day that the former died; After Kaworu's death, his soul was transferred to the Adam embryo in Gendo's hand, only to be absorbed by Rei 3 along with the hand in EOE.

Naoko Akagi?

Doctor Naoko Akagi.

At one time this was the most pervasive theory: the soul in Eva-00 is actually that of Gehirn's chief computer engineer, Ritsuko's mother, Dr. Naoko Akagi. The basis for this theory was that the people standing directly behind the glass in the control room when Eva-00 punches it -- Gendo and Rei -- are people for whom Naoko Akagi had a deep personal hatred. Gendo fooled Naoko into thinking he loved her, but was really only using her (as revealed in by Rei I in Episode 21). In a fit of rage, Naoko strangled Rei I to death, seeing her as Yui (whom she very strongly resembled) and as "competition" for Gendo's affections. Naoko had good reason to lash out at Gendo himself, even more than Rei, because he had used her.

This, however, is refuted by Ritsuko's knowledge that she was Eva-00's actual target. But could Naoko actually been after Ritsuko? Actually, Ritsuko got along well with her mother professionally, and they seemed to be on good speaking terms in the flashbacks from Episode 21, but more than once in the series (specifically Episode 13) Ritsuko reveals that they had a tumultuous personal relationship. In the series' present, Ritsuko was carrying on an illicit relationship with Gendo just as her mother had been, and Naoko might have seen this as "competition". Indeed, during The End of Evangelion, the Magi supercomputer Casper, based on the personality-aspect of Naoko as a woman, sided with Gendo over Ritsuko. Thus, IF the soul were Naoko's this could be interpreted as a reason to attack Ritsuko, however...

Nothing in this speculation explains why Gendo (and possibly Ritsuko) would use the soul of Naoko Akagi in Eva-00 in the first place. As she views Rei as a rival, and even went so far as to kill Rei's first incarnation, Naoko would be the absolute worst choice for a compatible soul. Although it would explain why Eva-00 seems to try to kill Rei 2 in Episode 14, if you ignore Ritsuko's statement that she (Ritsuko herself) was the target, it gives no explanation at all why Rei was even able to synchronize with her. It also gives no explanation for the vision of Rei that Shinji had in Eva-00.

Naoko proponents also occasionally distort the "mother in the Eva" rule by claiming that Yui, Kyoko, and Naoko were all mothers, completely missing the point that Naoko is not Rei's mother and that Naoko, like Yui, would be capable of refusing to synch with an unwanted pilot like Yui did in Episode 19 with Rei and the Dummy Plug. The only reason for using Naoko would be if Ritsuko was going to pilot, and she is the wrong age.

The Prevailing Theory

Rei 1

Rei 1 first appears.

The theory which has become more established is that the soul of Eva-00 is the soul of "Rei 1". There have been three iterations of "Rei Ayanami": Rei 1 (the first one, killed by Naoko Akagi), Rei 2 (whom Shinji met in the first episode and who dies self-destructing Eva-00 in Episode 23), and Rei 3 (who appears from the second half of Episode 23 through the remainder of the series and The End of Evangelion).

Some people have objected on the grounds that it is well established that all three Reis have Lilith's soul. Rei 2 is still alive and well, interacting with Shinji and Asuka in Tokyo-3, so how could her soul also be in Eva-00? This is explanained by the case of Asuka's mother, Kyoko Zeppelin Soryu. While Shinji's mother, Yui Ikari, completely absorbed, body and soul, into Eva-01, only the portion of Kyoko's soul containing her maternal aspects was absorbed in the contact experiment with Eva-02. Thus Kyoko was still alive and conscious, although the process of having part of her soul sucked out of her drove her clinically insane. Still, Kyoko established that one can lose part of one's soul and survive.

Presumably, an indeterminate period of time after Rei 1 died, a portion of her soul was placed inside of Eva-00, with the rest being reembodied in the next Rei Ayanami clone, Rei 2. This may explain why Rei 2's behavior seems detached and withdrawn from the world; just as Kyoko went clinically insane after having part of her soul separated from her body, having a portion of Rei's soul separated to put in Eva-00 might have drastically affected her personality, although it did not affect her to the extent of driving her insane. If anything, it's the portion in Eva-00 that seems unbalanced.

This explains why Shinji sees a vision of Rei in Eva-00; because the soul inside is a portion of Rei's soul. But the segment of Rei's original soul (from Rei 1) has branched off a bit from that remaining in Rei 2, because they are separated.

Some people have objected that the Rei which Shinji sees in Eva-00 looks like more like Rei 2, who appears as a teenager, than Rei 1, who died when she was still a small child. Other's disagree and see Rei 1. The, "it's a teenager" believers say this implies that Shinji is seeing an "imprint" (see the "no soul" theory, above) left by Rei 2 in Eva-00, and not the soul of Rei 1. However, as stated above, when this Rei reappears in Ep. 25, the script explicitly identifies this Rei to be Rei 1.

This brings us to Eva-00's behavior during the berserk incidents. Rei 1 might be resentful that she was killed. Rei 1 has motives to strike out at the same people Eva-00 attacked. She may want to hurt Gendo because he had her imprisoned in Eva-00. Her attempt to Kill Ritsuko in Ep. 14 can be seen as taking revenge upon Naoko either by killing her daughter or else she believes she is attacking Naoko herself. Her seeing Ritsuko with her natural dark hair could be read either way; she recognizes the connection to Naoko, or she is mistaking her for Naoko. In Episode 14, Ritsuko knew she was the target. Ritsuko is in a position to know whose soul was inside the Eva.

In Episode 23, Rei 2 directly confirms Rei 1's presence inside the Eva with the question, "Is this me ? The me inside the Eva?". It's also been suggested that after Eva-00 self-destructed and Rei 3 was created, as both portions of her soul were now available, she would have possessed her entire reunited soul. But as the only evidence cited is the difference in behavior between Rei 2 and Rei 3 this should be treated as theory. It could also be explained by any number of things such as resentment over being forced back to life. Rei 3's personality also appears much closer to Rei 2's than what is known of Rei 1's.

Finally, the idea of the "mutual compatibility experiment" in Episode 14 has been cited as confirmation of this theory. The intention of the experiment was to see if Shinji was compatible with Eva-00 and Rei with Eva-01, with any idea of compatibility with Eva-02 being dismissed. Because Rei is connected with both Yui and Lilith (herself) she should be able to synch with either Eva-00 or Eva-01, however it is much less certain why they would think that Shinji had any connection with Rei 1 that would allow him to synch with Eva-00, or what the purpose of such a potentially dangerous test would be in light of the previous berserk incident.

Conclusion

The Rei 1 theory has become the prevailing theory due to the number of people who view it as the stronger case. This is why other theories, such as the "Naoko" theory and the "No Soul" theory have faded, but not vanished over time.

Addendum: Recently Proposed Theories

Unit-00's Soul is an Unknown Fragment of Lilith's Soul

It has recently been suggested a fragment of Lilith's soul was seperated for the specific purpose of becoming Unit-00's soul. This theory has not undergone all the debate and vetting the other theories received, thus it in uncertain how the fan community will receive it. At least two objections have already been raised.

• The soul looks like Rei. The Evangelion philosophy of existence states that we are defined by our relations with others. Thus Lilith turns into Rei after their reunion in EOE. During her time as a human Lilith has effectively become Rei. But why would a soul fragment that had never been Rei look like Rei? Unless the very act of synching can alter a soul's appearance, Unit-00's soul must have spent some time as a Rei soul.

• A Lilith soul fragment wouldn't have as strong a motivation to go berserk and attack the other characters as Rei 1 or even Naoko (e.g. no revenge for her her own murder, or jealous rages. The motive would likely be simple resentment over being imprisoned in Unit-00.

As this theory is relatively recent it's status here is uncertain. After a more thorough debate and discussion, a consensus will be reached on whether this secton should be expanded, deleted, or left as is.