Rin gives off a bad boy appearance, but the truth is he gives a lot of shits. He gives a shit about Shiemi, and his friends, and his older man and his brother, and about whether or not people will like his cooking, about his grades and how no matter how hard he tries he just can't seem to make studying work for him; if Kuro has a soft enough bed to sleep on, if he'll ever make it to Paladin like he dreams, if Father Fujimoto is proud of who he has become. If he'll ever forgive Rin for letting him die.

But this, this might be wrong, but this he does not give one flying fucking shit about at all.

He's the bastard son of Satan, he has been called mean and disgusting things his whole life, even before his powers awakened. He's used to people seeing past his good intentions straight to his bad results; it barely bothers him any more when someone accuses him of being a devil (...maybe because that's just a fact at this point). He's a half-demon, Heaven ain't in store for him, never has been, only Hell. So the absolute hell not let his brother fuck him until he can't sit right in the morning?

Call it disgusting, perverted, wrong, whatever. Rin couldn't care less. Because at the end of the day it's about him and Yukio, showing a love for each other that only grows the older they get; no one else matters in this moment as he huffs out breaths with three of Yukio's fingers scissoring in his ass. This is only about the twins, no one else needs to stick their fucking noses into their business.

Thoughts die almost entirely as Rin croons and his tail curls, his younger brother's fingers brushing so sweetly against his prostate, causing his back to arch and his tail to curl against the pleasure. Even better, their dorm is entirely empty so they don't have to give a shit about anyone hearing them.

"Come on, hurry up already! You know I can take a bit of pain!" Rin huffs over his shoulder. Yukio gives him a sickly sweet smile in return.

"This is for the twenty-two questions you missed on the exam today."

The half-demon groans and bites down on his pillow as fingers twist deeper inside him. "I'm trying! Not my fault studying doesn't do shit for me!"

"Maybe," Yukio drawls out in a hum as he spreads his brother's ass, watching his fingers work sinfully into his pink hole. "I should just abstain from all this until you pass a test."

"You wouldn't! You want it too, don't act like such a cocksucker, Yukio!"

"I thought you liked it when I sucked your cock," his brother laughs.

Rin growls. "Don't you know you're supposed to respect your elders, four eyes!"

The fingers are withdrawn from him so quickly it makes Rin whimper, and when Yukio slams into him to the hilt with no forewarning the breath is punched out of his lungs. "Shut up already, you idiot." the younger says with a trace of a fond chuckle.

To make up for the slow preparation, Yukio sets a punishing pace with his hips. The sound of skin slapping against skin fills the room, along with their noises: Yukio's are little more than huffed out moans as he holds onto the back of his brother's thighs, leaving dark blotches where his fingers grip to match the bruises he'll have on his ass from the rough thrusts; Rin's are far more animalistic, almost growls the reverberate deep in his chest, coming out through sharp, clenched canines that bite into his lower lip.

"Such a spoiled princess," Yukio tuts between heavy pants. It's true that, since they started, he's craved this as much as his brother. Rin just clenches so sweet and tight around his cock, trusting Yukio so much that he lets himself come completely undone with ecstasy. "Throw a tantrum until you get what you want."

Rin gives a whine of pleasure and pushes his hips further into the air when his sweet spot is hit, the motion making his sensitive nipples rub against the sheets. "Shut up, mole face." His comeback might be weak, but he really doesn't care, not when Yukio is all but pounding into him, pleasure cascading through his body making his eyes roll back into his head and his mind less than blank.

And when Yukio wraps a hand around his tail, giving a couple pumps, Rin spills beneath him immediately with choked out whimpers of his name. The half-demon's muscles convulse around him, milking Yukio to his own climax. Warmth washes through him as he releases, then drapes himself across Rin's back; he makes his older twin unfurl them from where they have the blankets in and death grip and laces their fingers.

Both are panting hard - it may have still been rough, but that was one of their more gentle sessions. Having a demon for a twin, even if he is a submissive one in bed, means sex can be straight up cruel sometimes; yet it is never anything short of wonderful.

Yukio kisses across Rin's sweaty shoulders and the elder preens at the affection. Pulling his spent member out, Yukio gathers him close and they lay in each other's arms, ignoring that the soiled sheets need changing and they could both use a shower. Rin nuzzles against his brother's collarbone and leaves light kisses across the defined muscles just under it as Yukio cards gentle fingers through his soaked dark hair.

"I mean it," he says after a while of laying in silence. "If you don't get your grades up, I'll stop."

Rin bolts up. "Hey! Our birthday is coming up in a couple days, don't you think you're being too mean?" he pouts.

Yukio laughs and pulls him back down, running a calm hand over his back. "Okay, so I'll give it to you on our birthday and that's it."

"And Christmas."

"Those are two days apart." the younger grins.

Rin insists. "And. Christmas."

"Fine, our birthday and Christmas. But clearly you're thinking more about this than your exams."

Pouting, Rin tucks his head under Yukio's chin. "Whatever. Shut up already, you jerk."

Yukio laughs. His brother may protest, but the following evening Yukio thinks to himself he's never seen Rin study harder.