Warning:Shinji's life Spoiler's If you don't want to know Shinji Ikari's full series story don't read!
A bundle of contradictions, Shinji is an otherwise normal, in fact, very quiet and introverted 14 year old boy struggling with the same problems of adolescence that every teenager has to go through. But on top of everything, he suddenly finds himself thrust into the position of piloting a giant mecha, and tasked with the job of defeating gigantic monstrous beings called "angels", at the risk of his own life. And he's doing it for his father, who sent him away to live with relatives at the age of four, after the death of his mother, Yui Ikari. By all accounts, Shinji had a happy childhood...for a few years anyway. His mother was Yui Ikari, a scientist married to Gendo Ikari, who had become head of NERV. Yui, while a devoted mother, was also a brilliant scientist who achieved the cloning technology needed to help build Eva Unit-01. But one day, while working on the Eva, an accident (maybe) happened, and Yui disappeared.
Gendo, unable to attend to the desparate duties of commanding NERV in its struggle to build a defense for when the destructive angels reappeared, and raise a small child at the same time, sent Shinji away to live with relatives. He seldom had contact with the boy after that. Called back to NERV when he's just 14 years old, by a father he hardly knows, Shinji thinks that it is for a reunion, and instead, finds himself called on to be a soldier in a war against giant monstrous beings called angels...as a pilot of a giant mecha called an Eva...the most awesome fighting machine the world has ever known.
In the midst of the burdens of handling these new, life threatening duties, he must also struggle with the normal teenaged angst that any young male trying to make his way in the world must face.It's a heavy burden for anyone to handle, but one that Shinji, with some hesitation, gamely tackles. While Asuka pilots for honor and glory, and Rei pilots because she has nothing else in life, Shinji does it because it is expected of him. He doesn't want the role, but takes it on because he can do it, and does it well. In fact, in episode 1, Shinji is the first person to ever successfully pilot an Eva, and does it without training, defeating an angel in the process.By the end of the Evangelion TV series, Shinji has become more full of self doubts than ever. In the course of fighting 15 angels, he's seen Rei killed, and Asuka become comatose. At the hands of his own Unit-01, Toji, the fourth child is seriously injured and crippled. And then in episode Kaworu, the fifth child shows up, and becomes the only person who appears to understand and respect Shinji, even becoming his friend. Only that friendship is betrayed when Kaworu turns out to be the 17th and last angel, and has to die at Shinji's own hand.
By the end of the TV series, Shinji has become so full of self doubts that he has become emotionally paralyzed. But with no one to help him, he works through his own emotional land mines, and emerges as a stronger person.