Rin Okumura

Rin has an extremely compassionate and supportive personality, and a kind heart. He supports his friends and tries to encourage and help them in any way possible. He is also very protective of Yukio and aims to surpass him one day. However, Yukio often finds Rin annoying due to his frequent impulsiveness, stupidity, and his care-free attitude, which makes Yukio look down on Rin as much as he looks up to him, making it hard for Rin to be taken seriously by Yukio and his fellow exorcists, making Rin desperate to earn his brother's approval. He takes offense when Yukio accuses him of killing their father and pointing a gun at him, warning him not to insult him and saying that he isn't going to fight his brother. Rin is also revealed to be very fragile later on when Yukio begins to show signs of Insanity and Rin can't find any way to help him.

Although he generally hides it, Rin loved his adopted father a great deal and has nothing but good things to say about him. He deeply regrets that the last thing they did was fight, which resulted in Satan taking him over. Much like Yukio, he takes any insult against him very seriously and got really angry when Shura claimed he died like a coward. He also doesn't like people insulting Yukio, whom he loves and greatly respects.

Besides this, however, Rin is surprisingly even-tempered and laid-back and rarely gets angry without a good reason. Rin is often shown to be able to relate to people easily and connect their feelings to his own, such as Shiemi Moriyama's grief over her grandmother and Ryūji Suguro's ambition to defeat Satan. He is also able to understand Shiemi's desperate desire for friends, as he grew up with no friends due to being constantly harassed by bullies, children, and rude adults alike. In general, he is often the first one to try and make people feel better if they're down. He's not the type of person for school or studying, though he was able to gain a junior high diploma and become an Exwire.

Unlike his brother, Rin is immature, which leads other people into believing that he is younger than Yukio. Rin can also be very violent and tends to get into fights (possibly caused by his demon side). It's been noted by several people that despite being twins, he and Yukio couldn't possibly be more different. He is headstrong (literally, as well as metaphorically, as he was able to stop a charging demon twice his height by headbutting it) and is often very open with his friends. However, when his friends found out about his demon heritage, they become afraid of him, thinking that he is unstable which could lead to a catastrophic disaster, but they slowly grew close to him and accepted him during the Kyoto Arc.

Despite his usual hot-blooded and obstinate attitude, Rin is often shown to be more sensitive than he lets on, which is shown when he is stuck in Mephisto's mechanical prison in the Kyoto arc when Shiemi tries to rescue him and he denies her, openly crying, afraid of himself. He is also shown to have a soft spot for animals. At the beginning of the manga, the reason he had gotten into a fight with Reiji Shiratori and his delinquent gang was that they were torturing pigeons. He also attempts (successfully) to tame Kuro without killing him after hearing that he was once Shiro's familiar.

However, it is later shown that there is another side to Rin. Once Kurikara breaks, Rin's demonic heart is returned to him, and there is another conscious to Rin. This one is shown to be notably megalomaniac, obsessed with its own power and destroying things with that power. In a way, it is a conscious manifestation of Rin's demonic power.