"I mustn't run away…I mustn't run away…I mustn't run away…"
Will update in the future.
At this point in his life, Shinji's mental health is unstable but perhaps the most sound it could be throughout most of the Rebirth of Evangelion series. Though he does his best to avoid fear and stress through obedience, he also has that defense set as the foundation for most of his life. He believes his knows what he has to do to get through life on his own and that he will always be alone. It's a sad life but one Shinji seems to be able to live through without the added stress of the angels and Evas. It's because of those things that Shinji's mental instabilities seem to start growing worse in the future.
Shinji is a boy much like others his age. He is a scared boy who wants friends and the approval of his only living parent. He wanted to be able to lead a more normal life than the one he has. Deep down, he just doesn't want to be alone. He does wish for someone, especially his father, to take him into their arms and tell him it will all be alright. This is mostly thanks to his mother dying when he was young and his father abandoning him at the age of eleven. The unfortunate thing is Shinji doesn't make attachments quickly and is liable to sabotage growing connections due to this fear of them leaving and it hurting him. He also wants to be able to accept the fact he'll always be alone while not truly being alone. He has a complex about being alone that keeps him at arms length from most people and contradicting wants doesn't make it any better.
To cope with these conflicting wants, Shinji has adopted the defense mechanism to always do as he's told. He tries to silently follow orders and doesn't talk much either. He falls into a sort of; children are supposed to be seen and not heard mentality. Being a contradictory fourteen year old, he can ramble on when he's feeling distressed or scared about how he will just do as he's told and that he has no true freedom but most of the time he surrenders to repeating orders as a mantra and trying to walk through life with the thought that obeying orders will help him get through it all relatively unharmed.
Despite his drive to avoid what is hurtful, Shinji does know right from wrong. He strives to do what is right even if his own conflicting feelings tell him to run the other way. Though he may be scared, he will try his best to be good. This is shown when he agreed to pilot Unit 01 instead of the injured Rei. He wants to help people as well and is happy doing so without asking outright for anything in return. Truth is, he wants the praise and joy that comes from doing what is right, even if he doesn't always get it. He is a good boy at heart.
Shinji does also have the potential for change. It is inside him as is shown later in his life. He can learn to look at things from how others see them and can open up to others. It just takes him time to be able to push passed his issues to do it. Though as Shinji has positive potential, he also has negative potential. Shinji is easily depressed and each time he falls to it, it seems he falls further than the previous time. The boy is fragile. He needs and desires people around him to help him feel better but often has a hard time taking the first steps to do so. But if that potential inside of him can be woken up and if he can be nurtured in the right direction, he has the possibility to become a much stronger person than he is now.
Should Shinji form strong bonds with people, he becomes heavily attached to them. This often takes time and a sort of understanding about feeling alone or useless. There could be exceptions but usually there aren't. Once he has made these connections, he will do anything to protect those people. His fear of lost and sadness motivates him to go to huge lengths for people he sees as his friends. The switch side of this is he hates hurting those same people. If he feels he has, he will most likely try to leave and remove himself from their lives as a form of self punishment and protecting them from him harming them again. It is another unfortunate defense mechanism the boy has.
Overall, Shinji Ikari is a sad, scared, and very lonely teenager. He feels he is not worth a lot and strives nonetheless to make others proud. He yearns for praise and for the approval of his father. He desperately wants friends and perhaps even a family. The problem is he has half-succumb to the idea that he will always be alone and often falls back on defense mechanisms to avoid unpleasantness. He wants what is good and wants to avoid what is bad. The unfortunate truth is he doesn't know how to deal with the hardships of life and because of this seems weak. He's inexperienced and childish at times though has the potential and ability to be brave, even in the face of fear. He knows what is right and good and tried to be just that. He wanted to be wrong and to not runaway but it's hard for him to accomplish his own wants by himself. He mustn't runaway. That is Shinji in a nutshell.
Shinji is human through and through. In reality he has no real special powers or abilities outside of concerning Eva Unit 01. He has been shown to have a high sync rate with Unit 01 though his skills right now leave something to be desired. He also has shown to be able to make Unit 01 awaken after he passed out in his first and only battle this far in his canon point. Besides that, he has nothing much he can do.
Shinji also has talents in playing musical instruments, such as the cello and the piano. He also is a trigger for Impacts but the reasons are still a mystery.