Spoilers for Neon Genesis Evangelion and End of Evangelion follow.
In my copy of A Streetcar Named Desire, Arthur Miller refers to Marlon Brando (playing Stanley in the 1951 production) as a “tiger on the loose, a sexual terrorist.” Miller goes on to reference “[Tennessee] Williams’ celebratory terror of sex, its awful truthfulness and its inexorable judgements.” While that line can refer to the emotional trauma of many characters in Neon Genesis Evangelion, I want to focus on Gendo using sex as a weapon to achieve his goals.
So much of Gendo’s power throughout the saga lies in his disdainful yet magnetic personality that ensnares his victims. Starting with his wife and mother of his son, it is claimed that Gendo was only interested in Yui for her political connections. Yui either did not see through his facade or Gendo truly loved her and the claim of his mercenary love was a hit job. Eithher way she died in an experiment (possibly killed by Gendo’s soon to be lover, Naoko Akagi), which probably ended any possibility of Gendo being a decent man.
Gendo developed the evil of pure clarity of purpose according to Justin Charity and Micah Peters in one of their Sound Only Evangelion podcasts. Maybe Gendo was not ripped, firefighter calendar beefcake, but absolute drive and purpose are attractive traits to many people.
The first true victim was the aforementioned Naoko Akagi, a scientist working with Gendo. They had a relationship after Yui passed, but it is hinted that Naoko had something to do with Yui’s death. Maybe Naoko killed Yui or maybe she simply did not try to prevent Yui from dying. Either way, she was pleased Yui was out of the picture because she was caught in Gendo’s web. She ended up designing the Magi, a triumvirate of supercomputers, and laying the base for all of NERV’s secret research. Would she have done all this if she was not enthralled with Gendo? It is possible. But she was driven to suicide after choking a child who revealed Gendo was simply using her and referred to her as an “old hag.” That makes it seem like Gendo had unhealthy prominence in Naoko’s emotional being.
A few years later, Gendo was able to seduce Naoko’s daughter, Ritsuko. Ritsuko had seen her mother with Gendo, she was very aware that her mother had been in a relationship with the same man. Ritsuko’s expertise and her relationship with Gendo meant she was one of the very few people who knew NERV’s true agenda. Was she granted access to NERV’s agenda through Gendo? Considering what kind of man Gendo was, it is equally as reasonable to think she had access to NERV’s secrets and Gendo was using his relationship with her to keep her working and quiet.
Since Ritsuko had access to all of NERV, she knew Rei’s true nature. And she hated Rei for it. She considered a fourteen year old girl competition for Gendo’s affection, not a healthy mindset. Even if Gendo did not encourage these ideas of Ritsuko’s, he should have spent more time trying to disabuse her of them if he really cared about her.
In End of Evangelion Ritsuko either comes to her senses or completely snaps. She wants to destroy NERV by initiating the Magi self destruct sequence. However, she was betrayed; not by Gendo, but by her mother Naoko. Naoko designed the three Magi computers and in each implanted one aspect of herself: Naoko the scientist, Naoko the woman, Naoko the mother. Naoko the woman betrayed her daughter. That aspect canceled the self destruct. This is the power Gendo wielded. He was able to so completely absorb Naoko’s affections that he drove her to suicide but even after death she still sided with him over her daughter. Then Gendo kills Ritsuko.
The vast majority of NERV’s secret research was done by the mother/daughter combo of Naoko and Ritsuko. Both had a sexual relationship with Gendo. Gendo used these feelings and warped the two women into promoting his private goals within NERV without any regard for their feelings. There are many aspects of Gendo Ikari that prove he is a villainous character. His interactions with Naoko and Ritsuko show his willingness to prey upon their desires for companionship and closeness: sexual terrorism.