Dangerous (Rin x Shiemi)

Rin x Shiemi from Blue Exorcist:
Within the campus of a school for exorcists-in-training, a meek girl who has never really been outside her home meets a broken but strong boy who thinks he killed his own family. But after she falls in love with him, he accidentally reveals what he really is; the son of Satan himself! Will she support him in his goal to beat the shit out of his biological father, or will she leave the only friend and only love she's ever had?

So I know that some people reading this haven't watched the anime or read the manga (mainly some friends of mine) and so here's what basically happens without any spoilers:
There are two realms in the world: Assiah and Gehenna. Rin and Yukio are biologically the twin sons of Satan, and born to a human mother who died after giving birth. Only one of the two twins was able to inherit the blue flames of Satan, which was Rin. The two kids were raised by an exorcist named Father Fujimoto, and when they were young kids Rin would always protect Yukio from bullies and such. Rin got into a lot of brawls and fights even after Yukio stopped needing his help. And during a fight, a demon disguised as a human at first tries to convince Rin to go to Gehenna. He escaped back to his home where they were getting ambushed by many demons. A sword, called the Kurikara (which I don't really include in the story) had confined all of Rin's demonic powers and Father Fujimoto convinces Rin to take it. But after Rin had said to Fujimoto (don't ever call yourself my father again!" or something like that, Satan possesses Fujimoto's body. Fujimoto ends up fighting Satan within his own body and kills himself to prevent Rin from getting hurt. Rin is so devastated he makes it his goal to kill Satan and gets sent to a school for exorcists called True Cross Academy.