A/N: Hello everyone! As you may have already guessed, I love the Blue Exorcist anime, and I also love angsty and okay, sick kind of relationships. I couldn't find my favorite yaoi pairing of Blue Exorcist anywhere, so I decided I should just write about it myself. I don't know how, but this pairing struck me right away. Please, lovers of angst, enjoy! This starts from where Neuhaus first fought Rin and then the storyline changes between them.
"You fucking bastard's spawn! You think I'll ever forgive you? Satan killed my family before my very eyes! It's time to get my revenge!"
"Neuhaus, stop it!" Yukio screamed. His colleague had lost a lot of blood, but he was still out of it, ruled by his anger and hatred. For his brother's blood, for killing Satan's child, it didn't matter to him if he died trying. The man was blinded, attacking without any second thoughts, and Yukio was there, left, lying down, and totally incapable of helping his twin brother.
Rin sheathed his demonic sword, in front of the shocked eyes of his raging teacher. He opened his arms, and Neuhaus attack stabbed him at the left side of his belly, passing through. The blue flames surrounding him subsided, and so did his demonic features. He was in pain. "I understand." He was in pain, but he was bearing with it, strong and determined. His blue eyes were wild and resolved. "So if it eases your pain, you can do with me anything you like. You can hurt me as much as you need. But don't involve other people in this!" Paku was hurt, everybody else was in danger because of this!
Neuhaus eye, the one he had left, twitched. Was this how Satan's son had deluded everyone? He pulled his weapon out of the half-demon's body, and he let out a small scream in reaction to the pain. "How noble words, coming from Satan's offspring." His breathing had settled, his self-control had started to fall back into place. He had just found a way. He had found a way to reveal the true nature of that miasma to all of those stupid kids that worshipped and trusted him. "If only those words were true, wouldn't it be nice?"
"I mean them!" Rin was stumbling, cringing by the pain in his waist. He was clinging at his wound, his hands were all red and dyed in his blood, but he'd still look at Neuhaus fiercely in the eye. "I'm serious, I'm not lying. Do to me anything you want if it helps you!"
Neuhaus shot a look at Yukio. The youngest twin was unable to move. Still, he was a professor in this academy? Then he would at least understand the meaning of his following words: "Satan's son, are you familiar with the Crimson Vow?" Yukio's eyes doubled at those words. He tried screaming something at Rin, but one of Neuhaus tamed demon parts shut his mouth.
"Crimson Vow? What is that?" Rin questioned. His wound had already started healing.
"If you really believe those words you just said, then you should prove them by taking this Vow with me." Neuhaus explained. "This Vow was created by Exorcists to prevent betrayals among them. Since you've taken it, it compels you to follow by your sayings. You can't back down on it. At first, it would kill the ones disobeying, but better now, it makes them actualize their words. Once you take it, it binds you." Neuhaus noticed that Rin's expression hadn't changed. "But you'd never do that, would you? You're lying after all." He smirked. "Someone like you would never go that far to save those people. Demons only know how to lie well."
"I'm not lying!" Rin yelled at him angrily, once again. "And I'm taking that Vow!" He walked towards his teacher.
Yukio somehow managed to free his mouth. "NII-SAN, NO!" He screamed. "Don't you understand what you're doing?"
Rin gave Neuhaus his right arm. "He can do whatever he wants." He said, never breaking eye contact with his teacher. He wouldn't give this bastard the satisfaction of disregarding him as a demon. He would prove to everyone that he was not 'Satan's son' but Okumura Rin! No matter the lengths he'd have to dive into.
Neuhaus smirked. "I wonder how long you will keep that act on." He grabbed Rin's hand and started drawing some weird circles on it with his blood, which has still dripping from his arms. "You see, the Crimson Vow is completely legal. No matter what I'll do to you once we've taken it, I'll be completely legal." Rin didn't answer, he just kept staring at him. He's bluffing a great deal. Neuhaus thought. Well not for long.
After he finished the circles, he looked at Rin's eyes once again. Never did they show any signs of backing down. "Tell me what you told me before." He ordered Rin, entangling their fingers together, Rin's right hand and his left. Yukio opened his mouth to speak, to stop his brother, but no voice would come out of it.
"You can do anything you wish with me until you're satisfied." Rin said seriously, without any hesitation. "But in return, you'll never drag other people in this."
Stupid kid, you can't do it. I'm not buying it. "I accept that vow." Neuhaus responded. A golden glowstarted surrounding their hands. Come on, back off! How long are you going to continue this? Cower up and show me that disgusting, little, cheap demonic side of you!
Yukio watched terrified as the golden glow shined brightly for a moment and then disappeared, sealing the deal. Rin was still as determined as when it first started, but Neuhaus expression was unreadable. Yukio couldn't take it anymore. "Please!" He started begging. "Please Neuhaus! Don't kill my brother! Don't kill Rin! Please, please! Don't kill Rin!"
The tall dark-haired man slowly lowered his hand and parted from Rin's. Without saying anything, he looked at Rin's eyes for some moments and then left and walked away, disappearing in the shadows. The tamed demon parts were extinguished and Yukio was released. Rin ran over to his brother. "Yukio! Are you okay?"
"What did you do, Nii-san?" Yukio was trembling out of worry for his older brother. At Rin's arm, a little lower from his shoulder, a black daedal line had appeared, much like a tattoo. "Don't you understand that you gave him every right to kill you without even being prosecuted?"
"Yukio, if he was planning to kill me all along I don't think he'd worry that much about prosecution…"
"No nii-san, but then you could have fought back!" Yukio stated desperately. "Don't you understand? The Crimson Vow takes away from you the right to defend yourself! If he does decide to do anything, you'll be unable to stop him!"
Rin contemplated about for some seconds. Even if that was true… He didn't think Neuhaus would kill him. If so… "He didn't do anything. If he wanted, he would have."
Yukio sighed. "Let's hope that is indeed the case…"
Not so far away, hidden in the shadows, Neuhaus needed time to comprehend what had just happened. His mind had drawn a blank. Did a demon truly take the Crimson Vow with him? Did Satan's child just sell himself like it was nothing, only to protect mere humans? Either that kid was a pure idiot and didn't understand what his actions meant, or… Or he was bluffing. Yeah, that must be it. He was bluffing. He only took the Vow because he thought that Neuhaus would never use it. So this way he could appear like always, wearing his stupid smile, goofing around without a care in the world, winning the other kids liking and approval, while striking back when it's least expected… That's what demons do! He only disguises himself as a good guy so he can destroy us easily afterwards! Thinking that now he has everyone on his side…
Neuhaus gritted his teeth and curled his hands into fists as he took the decision of his next act.
Cursed demon, aren't you wrong! I'll teach you how this deal was the worst thing that could have happened to you!