Incandescence Sides

Dance With The Devil (Literally)

Summary: Rin still wants his dance with Amaimon but this time he's coming prepared and he knows just the demon to teach him. Set in between chapters 6 and 7 of Incandescence.

A/N Well, I'm currently waiting in agony for the new AnE manga chapters to come out so I can update Incandescence. Although, given that I suspect Mephisto may end up the big-bad at the end of the manga (and Amaimon dead if my usual choice of favorite character is anything to go on D:), you can bet Incandescence will at some point veer off the canon timeline bc I will see the ot3 together and happy if it kills me :D

Also, if either of those two things happen you can quote me on having called it ;)

Until then, I'll be putting all the (sm)fluffy side stories that didn't quite fit in with the main fic chapters into a collection of sides that happen off-scene.

Some will be pure fluff, some will be pure smut, and some will be a wonderful mixture of both, so hopefully you all enjoy the ride :D

And if anyone has cute side ideas they think might fit in with the Incandescence AU that they'd like to see written here, let me know! I've got quite a few but I can always do with more short scenarios to write up :)

I've been in a very MephiRin mood, guys idk. Poor Amaimon is gonna feel neglected if I don't write something about him, and we all know how he gets about being ignored lmao

Also, anyone else head-canon Rin (and Mephisto/Amaimon) as touch-starved? Like, I know Shiro did his best, but given the guy's lack of a normal childhood and zero parenting knowledge, coupled with the fact that Rin, being a naturally much more outgoing person, probably has higher physical contact needs than introverts like Shiro and Yukio would, means that our boy didn't get enough casual intimacy with other humans growing up. Especially since he didn't have any friends either until the ane show began.

For Mephisto/Amaimon (and the rest of the demon kings, though I hesitate to head-canon much about them until we know more/get to see them interact in the manga) I'm assuming they don't get much casual physical displays of affection (being generally seen as evil/untrustworthy by literally everyone for perfectly valid reasons) outside of foreplay and they don't even realize they need or want affection like that. Mentally, they might not want/understand it, but that's the problem with possessing a human body, you've also gotta take care of that body's needs lol

So when Rin comes in with his human notions of "What To Do When You're In A Relationship 101" and finally gets to shower his two demons in touches and all the things he's grown up lacking they're completely blindsided and have no idea why (or why their bodies are suddenly craving more), leading to many "Bluescreen of death" moments as they reboot their systems to deal with the virus that is humanity. That hilarious fanart of Mephisto going "what you're experiencing is love," and Amaimon going, "absolutely disgusting," is highly relevant. Though really, it's probably Yuri's ghost explaining it to the Both of them since nobody else in that show would have the guts to do it :D

I gotta add too that I know absolute babkas about dancing and I have two left feet (aka I'm the clumsiest, least graceful person on the planet and also an intp with the physical awareness of a rock) so if anyone knows anything about dancing for real and has suggestions for this chapter I am happy to take them so I can improve it :D

"I'm going to hang out with Ambrosia, Yukio. I'll see you in like a few hours to get things ready for dinner, okay?"

Rin was happy to ignore the twitch his words caused in his twin at hearing where he was going, shoving his feet into his shoes and gathering his things to head out from the dorm for the rest of the day.

"Did you finish your homework?" Yukio asked and Rin applauded his studious twin's efforts at trying to keep him from seeing Ambrosia, knowing how un-enthused he was about the two of them dating.

Especially with her being Amaimon's "daughter", his twin's cool attitude towards demons very apparent.

Well, Rin hid a snicker, Yukio would be a lot more upset if he found out who Ambrosia actually was, though Rin wouldn't be telling him that just yet.

He'd hold off on that reveal for a while longer. Maybe, Rin decided, once Yukio warmed up a bit more to Ambrosia he'd start to ease into the fact that she had a more demonic heritage than Rin had suggested when he'd introduced the two.

And that she was actually Amaimon, demon king of earth and, yes, Rin was dating him.

Also that Rin wasn't actually going to see Amaimon, though he was happy to use him as a cover story.

He waited until he was a few blocks away and into the city before pulling out his phone, feeling his heart fluttering in his chest at the call he was about to make.

Rin pressed his thumb to the number and the phone was ringing before he could psych himself out, heart jolting when the click from being picked up echoed from the speaker.

"Rin, what an unusual surprise," came the purred voice from the other end.

"Uh," Rin swallowed around his dry throat, mind blanking on what he'd called to ask, "hi, Mephisto."

"To what do I owe the pleasure of your call?"

Dammit. He knew demons were all about tempting others but did Mephisto have to make every word out of his mouth sound like such an intimate flirtation?

Rin mentally shook himself, leaning back against a nearby building before responding.

"Is Amaimon there?"

"He's out sightseeing. Again," Mephisto sounded put out at the question, grumbling, and, even softer, "he'd better get me something nice this time or I'm revoking his key access."

Still, that was what Rin wanted to hear.

"Good."

"Oh?"

"I was wondering if you could help me with something," Rin scratched his fingers against the brick behind him, finding claws had formed without his noticing as the surface crumbled into grit under the repeated motions.

"And," Mephisto drew out in a light tease, really not helping Rin's nervousness, "what would that be?"

Rin inhaled a long breath before getting his request out in a rush.

"I was thinking about what Amaimon told me at the festival- about how you taught him to dance and I was kinda hoping you'd be able to teach me too."

Silence came from the other end and Rin almost thought he'd lost the call for a moment, rolling his bottom lip between his teeth as he waited for an answer.

"Oh, Rin, I'd be delighted to."

He felt his cheeks heat at the barely hidden undercurrent of pleasure in Mephisto's voice and his mouth pulled into a smile despite himself.

"So, when can I come over, now or another time?"

"Now works just fine, Rin, I'm not busy. Can you find your way to my office?"

Rin gave the affirmative and hung up.

He heaved a sigh, finding he'd become almost lightheaded without noticing as he set to using his transport key on the nearest door, figuring he could cut the travel time short.

Although he almost decided to walk instead, a jittery feeling welling up in his chest and making his movements jerky, like he'd had too much caffeine.

He didn't know why he was so nervous, seeing as he was the one who'd made the choice to go to Mephisto. There was just something about the demon king that turned Rin into a restless mess in a way he wasn't- as much, at least, around Amaimon.

If he was the introspective sort, Rin might have tried to analyze why that was, but that was more Yukio's forte than his, so he let it be.

Rin forced himself to take a steadying breath and opened the door to Mephisto's office, entering and leaving the sounds of the busy street behind.

Mephisto was lounging on the couch and cheery electronic noises reached Rin's ears from the handheld game he was playing, tongue sticking out of the corner of his mouth in concentration.

"Not busy, huh?" Rin made his way over, hands on his hips as he surveyed the mounds of paperwork he could see piled on Mephisto's desk.

Mephisto grimaced as he paused his game, one hand tugging through his hair that Rin was just noticing looked a bit disarrayed. Though, now that he was paying attention, everything about Mephisto seemed out of sorts despite how calm he'd appeared over the phone.

"If I have to see one more report for the day, I might do something drastic," Mephisto growled. The glare he sent his paperwork vicious enough that Rin was glad it wasn't turned on an actual living creature for fear that it would literally stop their hearts.

Mephisto's growl deepened as his fingers caught in a knot in his hair, looking like he was about to rip out the stubborn strands when they refused to cooperate and untangle.

He had his hand up and over Mephisto's before he could think about it, both of them freezing at the unexpected move.

Rin gentled the snarled mess Mephisto had made of his own hair, pulling the black clawed fingers away to begin carding his claws through the strands while Mephisto stared up at him with wide eyes.

"Sorry, you looked stressed," Rin mumbled, cheeks heating again as he averted his gaze to focus on a tricky knot he'd discovered like it was the most interesting thing in the world.

"It always helped me calm down when someone played with my hair," Rin continued when Mephisto kept staring. "Not that a lot of people ever did, but sometimes Shiro or Yukio would when I was a kid so…"

Rin rubbed his thumb in a slow circular motion over where he'd just fixed another knot to sooth the sting Mephisto must have felt.

I see," for some reason that information made Mephisto narrow his eyes, the strange look gone just as quickly as he came out of his shock, "though didn't you come here for another purpose?"

"Uh, oh yeah," Rin blinked, realizing he'd become deeply, deeply side-tracked somehow, and pulled his hand from where he'd buried it in Mephisto's hair, feeling a sudden self-consciousness at his actions.

"Sorry," he said, shoving his hand behind his back like he'd been caught in the proverbial cookie jar.

Mephisto still hadn't said anything and Rin scrambled to explain. What, he wasn't quite sure.

"Er, I just figured if you had time- and I don't have anywhere to be for like, a few hours to go make dinner, though I can always cancel and Yukio can eat whatever Ukobach makes. Um," Rin was babbling, face heating with every stupid word that left his mouth.

"I guess it all depends on when Amaimon is coming back, or if you really are busy then we can just start the lessons so you can get back to work, I'm fine with that too."

Rin drew in a deep breath, dropping his head to hide from Mephisto's bewildered stare.

"I thought it would be okay to just relax on the couch until you felt better," he finished with another mumble, hands twitching behind his back until he clenched them into fists while he waited for Mephisto's reaction.

"That," Mephisto started, and Rin gasped as a snap came, finding himself sat on the couch with Mephisto's head in his lap, the demon's green eyes piercing into his from where he was now sending an amused smile up at him, "is a marvelous idea, Rin."

Rin's heart tightened at Mephisto's acceptance, a smile breaking onto his face as he happily returned to running his hands through the purple hair now pooled in his lap.

His smile softened as Mephisto went back to playing his game, the repetitive music filling the silence of the room while Rin got the last knot out.

He moved on from his work to massage at Mephisto's scalp, letting the pads of his fingers trace over the areas of tension as he relaxed into the motions.

Rin gathered the thick hair, making sure not to pull any strands or leave them trapped underneath and began twisting it into a bun, only to let it unwind to start the process all over again.

A sound reached his ears and Rin furrowed his brows as he tried to place it only to blink as he realized it was a soft purr, and it was coming from Mephisto.

He'd never heard the sound coming from the other demon before. Always it was a growl or snarl or something deep and dangerous that had the tendency to send a thrill through his spine when he heard it.

Mephisto purring did funny things to his heart, Rin was now registering, wondering if the demon was even aware he was doing it and paranoid that if he acknowledged it Mephisto would stop.

So he settled into the couch more securely to enjoy the rare moment of quiet.

Time passed like that, Rin having pulled his phone out to mess around on social media and the mindless game apps on it, his other hand still carding through Mephisto's hair in absent patterns.

He'd taken to grazing the pads of his fingers over Mephisto's brows and along the tips of his pointed ears when Mephisto sighed and flipped off his game, vanishing it in a pink cloud.

Rin set his phone away while Mephisto stretched out of the position he'd held for the past hour with a satisfied groan and several popping sounds as he worked out the kinks in his body.

The demon's arms extended over Rin's lap and Rin smiled at the scrunched eyes and contented grin of Mephisto's expression.

Then those arms were pulling him down into a kiss and Rin couldn't stop the surprised squeak the action prompted, though he was quick to return the kiss, the fluttering feeling back in his chest again.

Mephisto's palms were warm on his cheeks, claws lightly indenting his skin and sending shivers through him even as he tilted his head to deepen the angle.

Rin closed his eyes to get lost in the sensation, ignoring the way his neck ached at the weird position he held it in to focus on mapping out the insides of Mephisto's mouth.

He was the first to break, drawing back to regain his breath and staring down at Mephisto with lidded eyes as he tried to remember why he'd come to him in the first place.

"Thank you, Rin, that was a respite I hadn't realized I needed."

Rin blinked, shaken out of the haze he'd been drawn into, "uh sure, no problem."

He leaned back as Mephisto extricated himself from his lap, finding himself left with a sense of disappointment even though his thighs had gone numb from sitting for so long.

"Now," Mephisto began, striding to the center of the room and grinning back at Rin with his hands on his hips, "let's get to the real reason you're here."

A snap and Rin yelped, the casual hoody and jeans he'd been in gone and replaced by the suit he'd worn for the festival- also he'd been transported off the couch to stand in front of Mephisto, body wobbling at the sudden teleportation.

Rin looked up from his body to find Mephisto was also in a suit, the deep maroon of it looking weird with his purple hair but still somehow fitting him perfectly and Rin felt his own grin try to overtake his face.

Mephisto didn't hide the enjoyment he was getting from yanking Rin around, though, and Rin crossed his arms, shooting him an irritated look.

"I can walk, you know."

"And with my help, you'll even be able to dance," Mephisto teased, bringing his gloved hand up to his chin as he ran his gaze over Rin until Rin blushed from the obvious attention.

Then Mephisto had his hand on Rin's waist, pulling them flush together and leaning over him to smirk at the second cut-off squeak he'd surprised out of Rin that day, "did you have anything in particular you'd like me to teach you, Rin?"

Rin glared but didn't move out of the hold, putting his hands on Mephisto's chest and thinking about the question, "I guess whatever you taught Amaimon would be okay. I don't think I'm up for, like, ballroom dancing or anything."

"What has Miss Kirigakure been teaching you?" Mephisto sighed, probably put out by Rin's lack of appreciation of the fine art of dancing.

"Er, what do my sword lessons have anything to do with dancing?" Rin said to the seeming non-sequitur.

Mephisto brought his other hand up to Rin's hip, tapping a finger against his spine and Rin felt like the demon needed to be wearing glasses as he prepared for a lecture, "you have moved up from wildly swinging it around to some actual form and footwork, right?"

Rin winced at the remembered pain of Shura's lessons about watching his footwork, "oh yeah, those lessons."

"Yes, essentially, you're going to have to learn to not step on my feet, I don't need scuff marks on my nice dress shoes, understand?" Mephisto arched his brow at Rin and nodded down to indicate where Rin was almost standing on top of him already.

When Rin dutifully inched his feet away from the other's Mephisto continued, "and the next essential rule-"

Mephisto had his lips next to Rin's ear a moment later, breath just moving the wisps of hair to tease along his skin and Rin shivered, hands tightening on the suit under his hands.

"Trust your partner to lead," Mephisto murmured as he drew his hand up Rin's spine, the shift of fabric and deliberate touch rubbing over where his tail was hidden underneath, "you can't fight me, Rin. I know that will be difficult for you."

"I trust you," Rin said without thought, then flinched as the hands on him clamped down.

He pulled back to see Mephisto's pupils lost in the acid-green of his irises, a strange and warped smile torn open on his face to reveal jagged fangs as Rin quickly amended his statement before he broke the poor demon.

"I mean, at least to teach me how to dance. And to be yourself," Rin added, words slowing while Mephisto recovered from whatever that reaction had been. "I trust that."

Mephisto looked more human-shaped, coming back to himself, though the bright expression on his face was flimsy as he tried to start where he'd left off, "yes, well, as I said, trust. You have to trust my unspoken signals. When I step, you follow, when my hand presses yours, it's to lead. You can't tug away or try to go another direction, or we'll end up going nowhere."

"Okay, I got it," Rin nodded his understanding.

He found his attention drawn to the way Mephisto slid his right hand down his arm until he had their hands clasped together, his left hand moved Rin's to settle at his bicep, then cupped Rin's shoulder.

Rin squashed the nervous flutters in his chest that tried to make their third appearance for the day, though that was made difficult by the fact that Mephisto was rubbing his thumb in heated circles over his shoulder blade and smiling like he didn't know how distracting it was.

"Follow my lead, Rin."

Mephisto began, then, pressing with the hand at Rin's shoulder and pulling with his other while Rin tried to avoid stumbling into his chest.

It kinda was like Shura's lessons on footwork.

The thought come to Rin in a flash as he concentrated on following Mephisto around the carpeted floor of his office, finding it both easier and harder than he'd expected.

Easier, because Rin was quickly lost in the flow of movement, becoming surer of his steps with every slight correction Mephisto touched to his body.

Harder because Mephisto kept touching his body in ways Rin was positive weren't apart of normal dance lessons. Fingers caressed over the back of Rin's hand, stepping so that Rin's leg would brush between his or his between Rin's, the heat of their bodies building until it was the only thing Rin could focus on.

Then Rin found himself spun out in a twirl away from Mephisto, gasping at the shock of it when he came to a stop, held at the end of Mephisto's outstretched hand and he would have dropped to the floor if not for that.

"Hey!"

Rin's complaint cut off as he was pulled back in, dizzy and breathless when he came to a stop in Mephisto's arms to stare up into sly green eyes and fangs just peeking out from quirked lips.

"I'm sorry, Rin, would you have preferred a warning?"

"Would you actually give one if I say yes?" Rin bit out, glaring at the wide grin his question earned

"Stranger things have happened in the world," Mephisto hummed before leaning to shadow Rin, lips hovering just above his while Rin froze at the closeness.

Anticipation built and Rin licked his lips, pulse spiking as his gaze flicked to Mephisto's mouth.

"Let's continue, Rin."

Mephisto drew away, returning them to the straight-backed position they'd begun in while Rin's heart dropped at the disappointment he couldn't help feeling.

But Mephisto was already moving again and Rin had no choice but to follow.

They mirrored each other around the room, Rin becoming breathless for an entirely different reason as the physicality of dancing with Mephisto brought a thrill out in him and a fierce grin lit on his face.

This time when Mephisto directed him into another spin, Rin was ready, feeling a bubbling laughter trying to force its way past his lips where it welled up from his chest.

Rin couldn't have said how long they danced for, only knowing it had been a while by the way his body began to shake from the exertion but not wanting to stop, chasing the buzz of being so in sync with Mephisto.

Something gleamed in Mephisto's eyes then, and Rin felt himself tense, having become in tune with Mephisto's body signals and realizing he was going to make a move, though Rin couldn't guess what it would be.

Within a few steps, Mephisto had Rin whirled across the floor and slammed into the wall, pressing flush against him and stopping his gasped exhale with a rough, open-mouthed kiss that Rin moaned into a second later.

He shook against the demon king, adrenaline rushing through him at the sudden attack even as he did his best to get as much contact with Mephisto as possible, somehow keeping from digging his claws into the expensive suit through a minor miracle of self-control.

He groaned into the kiss as Mephisto shoved a leg between his, dragging his hips there as he tried to get more friction despite the smooth fabric so frustratingly in the way.

A snap from Mephisto and the clothes were no longer a problem, their heated skin now bared to the still office air, though Rin couldn't register anything beyond the body pressed to his.

He was finally free to claw into Mephisto's back, eliciting a hiss and earning Rin a sharp bite to his lips that drew blood.

The taste of his blood added to the feverish slide of their hips against each other, slicked with pre-come as the scent of the two became an intoxicating mixture in Rin's senses and he released, shattered groan muffled by Mephisto's tongue wound around his.

Rin panted until he felt lightheaded, clinging to the still moving body until Mephisto yanked his head away to take in heaving gasps of air, neck arched in his own release and Rin didn't waste a moment to attach his fangs over the proffered throat in a bite that only just didn't break the skin.

A growl vibrated out of his mouth, hips still rubbing against Mephisto's as he chased the aftershocks of pleasure coursing through him, something primal satisfied to feel Mephisto doing the same as they both came down from the high.

Rin laved his tongue over the captured jugular, eyes closing as his growl tapered into a purr, wriggling in Mephisto's arms as he slumped down on him in a heavy weight.

He became aware of a new sensation and cracked his eyes open, trying to place it, when he looked down and saw that somehow Mephisto's tail had wrapped around his calf, twitching the end of it to tickle at his foot.

It was enough to get him to release Mephisto's neck from his teeth, tongue tracing his lower lip in an absent move as he tried to understand the strange sight, though he couldn't quite place why it was so odd.

Rin tightened his arms, putting Mephisto's apparent loss of control over his tail out of his thoughts to nuzzle back into his neck with a contented sigh.

"You know, I don't think that's how most dance lessons go," he mumbled, smile forming at the chuckle his words got out of Mephisto.

Mephisto dropped his head to Rin's shoulder and slid his hands to his waist to rub at his hips.

"A pity, it might encourage more humans to learn the skill if it was."

Rin snorted, bringing his head away to rest on the wall behind him, "so how did I do?"

Mephisto left his neck with a measured drag of his lips there, enjoying the shiver it got out of Rin if the smile on his face was anything to go by.

"You're a natural, Rin. It seems you take to this well."

The praise made Rin break into a beaming grin, reaching up to tug the newly mussed strands of Mephisto's hair, "maybe I will learn the more advanced stuff. If you wanna teach me."

"Hmm, with such a willing student, I'd be a fool not to accept," Mephisto bent to give his answer, finishing with a slow slide of his mouth against Rin's.

Rin dropped his hands to Mephisto's arms to grip there until they broke apart and he let his lips quirk into a wicked smile.

"I can't wait to dance with Amaimon next. Do you think he'll be surprised?"

The slivering of Mephisto's pupils and slow scrawl of a matching smile across his face told Rin all he needed to know about how his surprise for Amaimon would go.

He couldn't wait.

And that's a wrap! Hope you guys enjoyed this little addition to the Incandescence AU and i hope it tides everyone over until I can get the next chapter out :) Let me know what you guys think!