
Gendou Ikari is the commander of NERV and father of Shinji Ikari. This is my favorite character in the series. Is he a hero or a villain? A noble realist or an evil anarchist? Never are we completely sure.
When we first see Gendou in Episode 1, he is speaking to Shinji for the first time in years. Even after all their time apart from eachother, this father has no kind words. He tells Shinji he was only called because he had a use, nothing more. Gendou forces his son to pilot Unit-01, and shows no regrets about putting his son in imminent danger. His demeanor seems cold and calculated. His pose of sitting with his hands folded under his face is enough to unnerve anyone looking at him. This is not a man to be dealt with lightly.
It is clear that Gendou is a also man with important responsibilities. He is the leader in charge of the defense of the human race, and he takes this post seriously. However, Gendou's crusade is not one of nobility or benevolence, but one of vanity and self righteousness. He is the protector of the earth from the angels, but there is nothing living on this earth that he is concerned about. To understand what drives Gendou, it is necessary to look into his history before the second impact, and his relationship with two people: Yui Ikari and Kozo Fuyutsuki.
When Gendou was a young man, he had a reputation for being a rogue, and had gotten himself into trouble. Professor Fuyutsuki was assigned to look over him, after he had gotten into a bar fight. Through Professer Fuyutsuki, Gendou met one of his favorite students, Yui Ikari. They got to know eachother, and finally on one of her walks, Yui admitted to Kozo that she had started seeing Gendou. Although Fuyutsuki did not want to admit it, he had feelings for Yui, and could not hide his shock when he heard this news.
Gendou became more involved with the Katsuragi research team, and was on the expedition to Antarctica before the Second Impact. Fortunately for Gendou, he had left the day before the disaster struck, conveniently taking with him all documentation. Although the UN officially declared that the Second Impact was caused by a meteor striking the earth, the real reason behind it was that the impact was caused by the energy released after shrinking Adam down into embryo form (read more about this in analysis). Gendou was obviously a part of this plan, and it just go to show what lenghs he will go to to achieve his ends. The world lost half it's population, but to Gendou, the ends would someday justify the means.
It was while working at NERV with his wife after the Second Impact that an event took place that would change Gendou's life forever In an experiment with Evangelion Unit-01, Yui was killed in a freak "accident". Her soul was taken into the Eva, but her body died. Actually, this was not exactly an accident. Yui knew that her experiment with Unit-01 would lead to a 400% sync ratio, and it was her wish to merge with the Eva. She wanted to make sure the future would be bright for Shinji, and so she sacrificed her body to become one with the Evangelion. By doing this, Yui was assured that she would be a major factor in any event that took place to help create Instumentality. She would make sure that nothing would ever happen to Shinji that he didn't want. Another result from her (a human), merging with the Eva is that she knew she would live forever. Although it would be lonely, the history of human civilization would be recorded forever, even after the sun, moon and earth were gone.
After this incident, Gendou was a changed man. Earlier, things like his research and his son were important to him. Now he had a more important goal, a reunification with Yui. And he would stop at nothing to achieve it.
To help ease his feelings of loss, while at the same time creating a means with which to return to his wife, Gendou cloned Rei Ayanami. Through her, Gendou saw his wife represented. He frequently had talks with her, and at one point demonstrated his love for her by recsuing Rei from an accident in her Eva. During the process, he burned his hands in order to save her. Although he is kind to Rei, he does not truly love her. In his twisted mind, he sees Rei as a manifestation of his wife Yui, and fools the first two Rei's into thinking he truly has feelings for them. However, the third Rei begins to see through this, and cuts off Gendou's arm at the end declaring "I am not a doll". Shinji often has trouble accepting the fact that his father likes Rei more than his own son. Although he does not hate his son, Gendou found that he could not love him without Yui, and abandonned him. To Gendou, his quest for a reunification with Yui was paramount.
To satisfy his ambitions, Gendou could not have been any ordinary man. Indeed, he was incredibly skilled at manipulating people, and acted as some kind of a puppet master for much of his time at NERV. The most obvious examples of his handiwork are the Akagi women, Ritsuko and Naoko. He did not actually love either of these women, but both of them had a use that was critical to his plans. The way he treated Naoko and Ristuko bears an uncanny resemblance to the way in which he dealt with Shinji, putting them to work because they had a use, nothing more.
Naoko was the one who originally came up with the MAGI theorems and was a critical resource in their development and construction. Gendou needed her to make these, and to make sure she stayed, he became involved in an affair with her. Naoko realized that he could never forget about Yui, but it was acceptable to her, and they became involved. When the MAGI were complete, and Rei I told Naoko that Gendou thought of her as an old hag with no use once her job was done, she realized that she had outlived her usefulness in the eyes of Gendou. She took Rei's life before taking her own in an emotional outburst of disgust,rage and hopelessness.
Ritsuko was aware of the affair between Gendou and Naoko, and she was aware of the consequences of loving a man like that, but she obviously didn't care. The computer genius let lust cloud her normally good judgement, and she too fell in love with Gendou. History was fated to repeat itself however, and Ritsuko accepted the fact that she could not beat Rei/Yui for his love. In a act of hate and revenge, she destroyed the dummy plug facility that held all the Rei clones. Later in the movie, Ritsuko tried to self destruct the MAGI, but her mother Naoko, whose aspects resided in the MAGI even after her death, chose Gendou over Ritsuko, and refused her command. Gendou takes out his gun, and whispers to Ritsuko that he really did love her, but she recognizes the false statement, calling him a liar before Gendou shoots her.
In his post, Gendou is relentless. He brushes away all sentimental feelings when it comes to destroying the angels. He would not hesitate to put a battered and bruised Rei into combat if it served his purpose, and sent Asuka out as a decoy even when she could not fight. When Shinji pleaded with him that he didn't want to kill the pilot of Unit-04, Gendou removed the control from his son and watched with a smile as the dummy plug system took out Toji from his Eva and crushed his entry plug. Gendou continues to behave in this manor throughout the entire series, and only really changes while instrumentality is happening.
Near the end of the movie, we find the true Gendou revealing his feelings to Yui. It is then that we find out that the stone faced statue, who at times seemed inhuman, turned out to be as weak and fragile as any other person. Like Shimji, he could not understand the concept of anyone loving him, and realized that all he ever wound up doing was hurt Shinji. The one person who managed to break through his hatred for humanity in his life was Yui. Once his suppressed emotions were opened a crack, they all came spilling out, which made his love for Yui incredibly strong. After her death, the momentum of his love for her carried him along his quest to find her again. This is the focrce that drove Gendou.
In a scene that seems to be almost derived from Shakespeare's King Lear, we see Gendou play the role of Edmund as he spends his last moment apologizing to Shinji about what a horrible person he was. The question is, whether Gendou truly sorry or whether he is only saying this because he has met Yui. If he had failed, and reached his death without seeing Yui, would he have said the same words? It is up to the viewer to decide.