All About Ritsuka
In the first volume, the story alludes to an abrupt change of personality occurring in Ritsuka two years prior. It is seen often through flashbacks, when his mother beats him and denies that he is truly Ritsuka and that he is actually someone else in his body. He became the opposite of his former self. Before, he was a popular, academically average student; now, he doesn't get along with his classmates, and he purposely points out their faults, often expressing that he "hates this and that" aspect in a person. He gets perfect scores in school. In addition to the personality change, he suffers a loss in memory. The cause of these drastic changes is still unknown, although he has regular therapy sessions to determine why.
On his first day at his new school, Ritsuka meets Soubi Agatsuma for the first time. Soubi confuses him with his sudden intimacy and puzzling claims that he was Seimei's friend and Fighter Unit. As Ritsuka discovers, Seimei's impromptu will dictates that Soubi shall "become Ritsuka's" upon his death. Later in the series, Ritsuka falls deeply in love with Soubi, afterwards Ritsuka realizes he's destined to love Soubi.
Ritsuka deeply admired and idolized Seimei, and to discover later that there were many things kept secret came as a great shock. It further poisoned his difficulty in trusting others, particularly Soubi. He had a friend from his previous school, Osamu. Osamu has stated that Ritsuka used to be in a photography club in his previous school. Ritsuka usually takes pictures of humans, while Osamu takes pictures of flowers and plants.
Despite his young age and inexperience, Ritsuka is very intelligent and approaches things with startling maturity. The circumstances of his life encourage his lack of innocence; however, there have been notable incidents that bare his still-strong naïveté, particularly in sexual love and dating. Despite this, he still has firm opinions and unrelenting ideas about those subjects. It is these opinions that clash dramatically with adults and authority figures around him, most notably Soubi. Ritsuka is a pacifist, and strongly opposes violence under any circumstance.
Love is an uncomfortable subject for Ritsuka. He is wary of compliments, and doesn't like hearing phrases such as "I like you." Early on in the series, Soubi says "I love you" frequently, which Ritsuka doesn't believe is true and, at first, has trouble tolerating. Because of Ritsuka's cynical reaction, Soubi stops saying it altogether after volume 2 of the manga. Still, Ritsuka's inner conflict over whether he believes what Soubi says becomes a source of great tension and bitterness in their relationship.
All About Soubi
Soubi is a twenty-year-old student, studying Japanese art. He is a former student of Shichisei Gakuen ("Seven Moons Academy"), a school for fighters, where Ritsu Minami was his teacher.
As ordered, Soubi contacted Ritsuka after Seimei's death. He introduced Ritsuka to the world of fighters and sacrifices and told Ritsuka he would be his Fighter Unit. He fought beside Seimei for some time, and many people believe that he is Beloved's Fighter Unit. The appearance of Nisei in the manga, however, proves this to be false later in the manga. Soubi now fights for Ritsuka as Loveless, which is considered taboo because there is not a fighter-sacrifice bond between them. There is also a severe loss of strength, and in Soubi's case, his markings bleed in battle. Soubi was revealed to not have a true name at all — in fact, Ritsu comments that he is a blank slate, and whatever marking he is given becomes his name. Since Seimei carved Beloved into his skin, it became his name. When given a command to break the windows, courtesy of Seimei, in volume 8, it is shown that he cannot disobey, no matter how strongly he is against it.
Soubi appears to know much more about Seimei and his cause of death than he will divulge. Despite Ritsuka's insistence that he tell him everything he knows, Soubi refuses. In volume 5 of the manga, he even says, "Seimei is my God." He openly declares that he lives his life by Seimei's orders, but still says he'll obey Ritsuka's every order, which is not necessarily true. Nevertheless, he unintentionally fell in love with the younger boy.
In the beginning of the series he frequently touches, kisses, and caresses Ritsuka, but on many occasions states he is not a pervert. As the series moves on though, it becomes clear that he does truly love Ritsuka despite the fact he also acts as a protective brother figure, regardless of the sexual innuendo present.