"I mustn't run away"
I'm not worthy of piloting an EVA, because I don't understand anything. I'm incapable of doing anything good for anybody else!
Shinji Ikari is the main character of the Evangelion series and one of the most seriously psychologically flawed protagonists around. Evangelion in general is pretty interesting because of the way that so much of its action can be taken as allegories for or illustrations of psychological problems and shinji himself embodies a lot of these.
Perhaps the most notable is the Hedgehog's Dilemma that consumes him. Shinji is, in general, a very shy character who tends to avoid human contacts out of fear for saying the wrong thing or letting someone down. In general the concept is the dilemma all people face between making connections with people and risking getting hurt or shutting themselves away in total isolation to protect themselves. For Shinji,this dilemma is intensified by his duty as the Eva's pilot. He not only has a duty to society but is in turn almost wholly responsible for its continued existence and the safety of the other two pilots.
His inability to cope leads him to on several occasions attempt to abandon his duty only to be pulled back in for a combination of his feelings for Rei and his sense that humanity is in fact worth preserving. Shinji is lead further and further down a dark path, however, and his continued series of mental breaks ultimately leaves him a shattered husk, redeemable but horribly flawed-- much like the humanity he is meant to protect and in my opinion symbolize.
The powerful psychological and metaphorical implications of his character really do make an otherwise self-admitted terrible person turn into one of the most interesting fictional characters out there. If you haven't seen Evangelion yet thinking it was just a typical mecha, I urge you to look past that so that you can enjoy some of the most cerebral fiction out there.
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