Something interesting about Subaru is the way his messy self perception and struggles with his body dictate a lot of how he acts as a person. It's unique to me for a protagonist of an isekai series. He accepts his current situation straight away as an escape from his old life.
Subaru decides to make the most of it, in hopes he could become a better person in this new reality, unlike the disappointment he was in his past life. However, straight away he quickly realises he doesn't have any powers, nor was he any different from how he used to be.
This changes when he meets Emilia. A girl who represents his ideals but also someone he feels he can change himself to be around. Due to this he spends the entirety of the first loop trying to get into her good graces. He plays up an exaggerated version of himself to do so.
Emilia's honesty is something he appreciates about her. He received this from the people in his old life. However, he then dies in his attempt to do this and awakens where he started. His initial efforts seem wasted, and he becomes more frantic in his desire to do something.
Subaru focuses all of his attention onto others who helped him in a way to distract himself from his self. Subaru's sense of self is fractured, he takes in aspects of the people he admires into the self he portrays in public. Despite this, he's honest about himself to others.
It's also interesting how one of his biggest insecurities is the way his body developed during puberty. The happiest he was with himself was when he was an androgynous child. It can be implied Subaru gender nonconforming in some regard, whether transfem or just out of the binary.
This fact is why he idealises women so much. He feels like his life would be easier if he didn't have all the pressure of the masculine hero stereotype to fulfil. Due to this, a lot of his strength actually comes from his intelligence and the way he adapts to situations.
I find it really interesting how the storyline of Re:Zero is a story of a boy discovering himself through trial and error from the strange new world he found himself in. Subaru is one of the most complex fictional characters to me and this aspect is one of the reasons why I love him.
