Karma

Rin's mother died when she had Rin and his brother, he was taken in by a surrogate father who raised him and taught him christianity and told him about satan. There are little creatures that terrorize people and are called demons, he taught Rins brother how to protect Rin and deal with these demons.

Rin was very troublesome growing up, often throwing fits of rage and biting and attacking other kids. He doesn't know why hes so angry at others and cries a lot because he cant make any friends.

Rin was forecibly taken into an alleyway and beat up with the other kids mocking him and calling him a demon. Rin normally gets into fights but this was cruelly unfair, three against one? Before Rins father could come and rescue him, he lost his temper and exploded into fire and rage. This is where he learned he was the son of satan. He attacked one of the kids while the others ran off, only being stopped by his father. Because Rin was upset about his heritage, he accused his surrogate father of never loving him and only seeing him as a monster, this made him drop his gaurd and his father was possessed by satan, who then kills him. Rin blames himself for his surrogate fathers death and never forgives himself for his actions.

Rin goes to a school to learn to be an exorcist just like this father was, and just like his brother is. He finds difficulty in paying attention in his classes and prefers to learn via experience rather than books and studying. Rin tried to keep his heratage a secret from the other students but when his secret is revealed, he becomes an outcast and unintentionally hurts them when he tries to befriend them again.

Because everybody sees him as a demonic uncontrollable monster, he starts to believe it too. The only one who gives him benefit of the doubt is Shiemi who helps everyone accept Rin for who he is. Rin hates his biological father with a passion and swears to them he will kill him.