Archive of Our Own

Senku Ishigami was all about logic. He always had been. He knew that, Taiju and Yuzuriha knew that, Byakuya knew that, hell, even the kids in his science club knew that.

So for what possible reason, did he agree to the completely and utterly 𝘪𝘭𝘭𝘰𝘨𝘪𝘤𝘢𝘭 suggestion made by his unlikely friend, Gen Asagiri, of letting the dark haired magician give Senku a blow job under his home desk? Nothing about this situation was in any way logical, no matter how Senku tried to twist and turn it in his head. He was supposed to be examining the photos posted online of the stone swallows, as well as the one he had collected and brought home with him, but instead he had the ultimate distraction under his desk.

It had started completely innocent, or as innocent as an interaction between a scientist and a mentalist who both have loose morals could be.

Gen didn't have work that day, and decided to wait inside Senku's apartment for him to get home from school (Senku had given him a key, for some unknown reason). He greeted the green-haired boy as soon as he walked in the door, with his usual boisterousness.

"Dear Senku!" Gen exclaimed, throwing his arms up in the air as he skipped towards Senku, "You're finally back! It felt like I was waiting for orever-fay!"

Senku dodged his attempted hug with practiced ease. Gen figured he got that from how often his adopted father tried to do the same thing.

"Hang on," Senku grumbled, "let me get at least one millimeter inside my house before you assault me." Gen giggled and slid back enough to allow Senku to step further inside. He noticed something that looked like a tiny statue in Senku's hand as he walked past him. Gen tilted his head to get a better look at the thing, but that proved to be futile.

"What's that thing you're holding?" Gen decided to finally ask.

"This," Senku raised his hand to show Gen the statue, "is the latest anomaly that I've taken an interest in solving." He had that glint of enthusiasm in his eyes he always got whenever challenging science was involved.

"Oh really? And what makes it an anomaly? It looks like a regular statue to me."

"I think it's a real swallow, and I'm gonna figure out everything about it. Ten billion percent of it."

Senku walked down the hall to the room in the apartment meant for his science work, his lab, "You're welcome to join me, if you promise to not be a distraction," he said from the threshold.

"That's a lofty ask-tay," Get said as he followed Senku into the room. When he entered Senku had already shed the top layers of his school uniform and was crouched in front of his mini fridge, looking through his assortment of Monster Energy Drinks. He stood up and tapped the top of the can with his fingernails before popping it open.

"So you decided to join me, eh Mentalist?"

Gen's gaze traveled around the dark, slightly cluttered room; he always found it a bit strange that Byakuya had allowed Senku to have a whole room just for his lab stuff, "Well, I don't really have anything else to do."

"Fair enough," Senku said. He set the Monster and the swallow statue on his desk and sat in his chair. There was no separate chair for Gen to sit in, since Senku tended to work alone, so he just sat on the floor nearby.

Senku rolled his sleeves up to his elbows, and Gen would be lying if he said he didn't find that weirdly attractive. Of course, to Gen's torment, Senku also decided to unbutton the top button on his shirt.

Gen felt his heart rate spike. His eyes trained on the bit of exposed skin of Senku's chest. He felt like a man in the Victorian Era seeing a woman's ankles.

"Are you getting undressed for me now? How sweet," Gen disguised his interest with a jest.

Senku rolled his eyes. "In your dreams, Mentalist," he said, but Gen still caught his smug smirk.

"Too ad-bay."

"Yeah. Too ad-bay."

The two of them fell back into a comfortable silence once again. Gen watched the way Senku worked, looking at things online, observing his own statue, taking notes, but mostly he stared at Senku's chest and arms. He felt like a common pervert. Although that thought didn't disturb him much. Gen was content to just sit and watch Senku do his thing, even if his thoughts weren't so pure.

Senku's face grew pensive. He was clearly deep in thought; something must've stumped him. Gen loved the way Senku looked when he was trying to figure something out. The way he twirled his pen between his fingers reminded the mentalist of some of the slight-of-hand tricks he'd perform on TV.

Senku put the back of his pen between his teeth and used them to hold it there.

For some unexplainable reason, Gen couldn't help but find that incredibly hot. There was absolutely nothing sexual about it, but the mind wants what the mind wants.

"Hey Senku," Gen said, extending the 'u' sound of his name.

"Hm?" Senku didn't even glance at Gen when he responded.

"What are you inking-thay about?"

Senku grabbed the pen and removed it from his mouth to speak more clearly, "well it's obvious these are real swallows-" to Gen it wasn't, they just looked like really detailed statues to him, but he kept that thought to himself, "-but if they were petrified, then it should either be just the outer layer of their body, or all the way through, right?"

Gen nodded like he understood, which he did, but only about fifty percent, and he knew the more Senku talked, the less Gen would understand.

"Well," Senku continued, "if they were petrified all the way through, then the structure of their internal organs should still be intact and clear, but when you look at pictures of broken ones, it's solid all the way through. No sign of any internal structure."

Gen resisted the urge to suggest that they were just statues, knowing Senku would probably say 'not one millimeter of a chance' or something like that.

Senku put the pen between his teeth again, "So I'm trying to figure out why that is," he said around the plastic. Gen couldn't believe how sexy the man in front of him was. It was making it hard to think.

"Feeling umped-stay?" Gen asked.

"Yeah. There's not enough information to even form an idea."

Gen stood up, "I might be able to help you think of some." Senku looked at him out of the corner of his eye and raised an eyebrow. "Well, not directly, but..." Gen added.

"But what? Spit it out, Mentalist." Senku said. His smirk was the hottest thing Gen had ever seen.

"I can help you clear your mind. I'm quite good at stress relief," Gen added a sultry lilt to his words.

"I don't really think I'm particularly stressed, just a little brain blocked."

Gen sighed, of course the scientist had taken his words literally instead of getting what Gen meant. Gen grabbed the top of Senku's chair and spun it so that they were facing each other. Senku observed him critically.

"Senku." Gen said, staring the other man in the face, "I. Want. To. Blow. You."

Senku's jaw dropped slightly, enough for the pen to fall out of between his teeth. He stayed silent. At first he was shocked, obviously, but Gen could tell that that shock eventually turned into careful calculation. He waited patiently for Senku to answer.

"Why?" He finally asked. Of course, Senku was looking for another variable to add to whatever mental equation was going through his head.

"Never ask a magician to reveal his tricks, Senku dear."

"That's not a trick! It's a proposition!"

"Emantics-say. It doesn't matter."

"I'd say it-" Gen cut him off with a finger to his lips.

"Yes or no, Senku?"

"I guess... It might help," Senku said, obviously trying to rationalize what was just simple desire.

And that's all it took for Senku to end up with a scheming magician under his desk with his hands on his knees. Senku knew that if he looked down he would see Gen's sly face and whatever his version of bedroom eyes were, so he kept his gaze on his computer. Despite how blase he was most of the time, he found himself being uncharacteristically awkward in this situation. He considered that it might have something to do with the fact that he's a virgin, but Senku had never been afraid of trying new things before.

Senku felt Gen's lithe hands dance up his legs, just barely caressing the topmost part of his inner thighs, and concluded that it wasn't the time for him to work out a personal dilemma. Gen squeezed Senku's thighs, close to his hips. He still didn't look down.

"Damn, Mentalist, you sure do take your sweet time," Senku said. If he were to be fully honest, he'd say that the slowness was making his nerves spike, but he wasn't about to admit that.

"Well I can't just dive right into it when it's your first time, now can I? I've gotta find what's to your taste," the mentalist replied, as casual as if he were explaining how the human metabolism works.

"How do you-"

"How do I know that you're an irgin-vay? Now I'm not trying to insult you, Dear Senku, but it's obvious. You're the epitome of a science nerd."

"Science nerds can have-"

"Not you," Gen interrupted for a second time, I doubt you even jerk off as often as a typical teenage boy does."

"Stop interrupting me! And you're right. I don't really masturbate all that often, keen observation."

"Well I 𝘢𝘮 a mentalist, it's my job to read people."

"Yeah yeah," Senku said. He normally wouldn't be this dismissive but this situation was messing with his head, "will you just get on with it already?"

"As you wish, my dear Senku." Gen moved his hands up to Senku's hips. He gently slid his thumbs along the epidermis layer of his skin right above his belt. Senku hated (and loved) how light Gen's touches were. Of course the 𝘮𝘦𝘯𝘵𝘢𝘭𝘪𝘴𝘵 would like to play around with his sexual partners, of which he likely had many. Gen's hands moved further up, sliding under Senku's shirt and grabbing hold of his lower waist. His hands were cold.

"Your hands are fucking freezing, Mentalist," Senku commented.

"Gen."

"Huh?"

"Call me Gen when I'm about to give you a blow job."

Senku could feel the blood rush to his face, and slightly to the reproductive system, because of how blatantly the other had said 'blow job'.

"I guess that makes sense, Gen."

Gen hummed, "Thank you, Senku." His hands moved to unbutton the bottom button on Senku's shirt, but he stopped him with a question,

"Wait, why are you undoing my shirt if it's just a blow job?"

"So many questions and comments, dear Senku," Gen sighed dramatically.

"I 𝘢𝘮 a scientist."

"Fair enough. I am undoing your shirt because I simply want to see more of you, is that so ong-wray?"

Senku sighed and closed his eyes, "Do whatever you want, Menta- Gen."

The boy below him chuffed, "You don't need to tell me twice."

Gen began toying with Senku's belt. Senku heard the sound of metal colliding as Gen pulled it open and Senku felt his jaw tense. He took a deep breath through his nose.

Gen slid the belt through its loops and Senku's heart rate increased by at least ten billion.

Gen seemed to sense Senku's hesitation, "We can always stop if you're unsure," he said.

"No. It's alright. It's just a new and, arguably personal, experience," Senku explained, "I'll let you know if I want you to stop."

Gen nodded and let Senku's belt fall to the floor. He used one hand to slip the top button of his pants through the loop. Senku's heart hammered in his chest; he flexed his fingers in and out of a fist shape. He heard the zip sound of his fly being pulled down, just barely above the sound of his heart pounding in his ears. He wasn't used to being in situations like this, he'd never even watched porn before. It never interested him, and it was all fake anyway. But now he was about to experience something he'd never even thought of, and the one doing it was one of his closest friends.

"Eally-ray? Periodic table boxers?" Gen's voice pulled Senku out of his head.

"Well, you know me, I love science."

"Enough for it to be your undergarments, apparently."

"Yeah."

Gen hooked his fingers over the rim of Senku's pants and pulled them down. He raised his hips up to aid their descent. Gen didn't pull them all the way down, just enough to be removed from his hips. Gen tugged on the elastic of his boxers and then let them snap back. Senku yelped and flushed from embarrassment. Dammit. Gen was toying with him again.

"Dammit, Gen, get on with it already. Or do you plan on prolonging this for ten billion years?" Senku griped.

"Hm. Someone's excited."

Senku scoffed. He wasn't about to tell Gen he was right. He was excited, and mostly curious, about the event that was about to ensue. He could also feel himself becoming more erect. Fuck, he was nervous. Gen was going to be the first person to see his dick (outside of doctors and Byakuya, who would bathe him when he was too young to do it himself) and that would be nerve-wracking to anyone, even Senku.

It was as if time itself had slowed down when Gen started to pull down his periodic table boxers. He closed his eyes when they were pulled down to where his pants rested.

Holy fuck he could feel Gen's breath on his dick and it was so much hotter than it should've been.

"Wow," Gen said. He sounded astounded, "Senku, have you ever measured yourself?"

"Yeah... Once or twice. Five inches if memory serves me right... Six when erect..." Damnit why was he so awkward? He was never this awkward.

"Ah, so you're a grower then?" Gen asked. Blood rushed up to Senku's face and down to his crotch.

"Sure."

"But you're only half hard, we've gotta get you to full mast."

"Gen I'm gonna need you to stop talking like that before I fucking lose it."

"Ine-fay," Gen relented, easily.

Gen moved his hand and Senku could feel it hovering around his cock.

"Can I touch you?" Gen asked.

Senku nodded. Gen gently wrapped his hand around the base and Senku let out a gasp. It felt so much more intense than the rare times he did it himself. He supposed it had something to do with the neurotransmitters in his brain and their connection to his muscles and nerves, the same reason why you can't tickle yourself.

"Senku. I want you to look at me, " Gen said.

"Huh? Why?" Senku didn't know if he'd be able to handle the sight that awaited him.

"Because I like to put on a show when I do this. So will you look at me? Pwetty pwease."

Senku sighed and opened his eyes, angling his head down to put Gen in his field of vision. Just as he thought, the sight was overwhelming. Gen, on his knees, between Senku's legs, Senku's cock in his hand, and the most sultry smile Senku had ever seen. He felt his mouth run dry and his cock twitch in Gen's hand, who responded with a light squeeze at the base.

Senku reached forward and snatched the can of Monster from his desk. He knocked the drink back as if it were a shot of alcohol that he needed to get down quickly. He just wanted to get rid of the horrible dryness in his mouth.

Gen chuckled, "Liked what you saw?"

Senku set the drink down, "You could say that."

"Keep looking. It makes the situation 𝘵𝘦𝘯 𝘣𝘪𝘭𝘭𝘪𝘰𝘯 times better."

Senku looked back down at Gen and his cock twitched again.

"Ready? I'm gonna stroke you to get you hard," Gen said. Senku nodded and Gen began.

The slow, gentle drags of Gen's soft palm against his half-hard cock was one of the best things Senku had ever felt. He let out a choked gasp. Of course, it was no surprise that Gen was skilled at this, but experiencing that skill first-hand was something else entirely. Senku could feel the blood rushing to his swiftly hardening cock because of all the mentalist-induced arousal.

"Hm. That didn't take long," Gen commented.

"Shut up. I told you I don't masturbate often, and I'm still a virgin, so my body is a little naive when it comes to this."

"Oh well!" Gen exclaimed, "that just means we get to the really un-fay part quicker! The blow job! Just tell me when you're ready."

Senku took a deep breath and flexed his fingers a couple more times. He knew Gen well, and he would probably toy with Senku still, so he didn't need to worry about it being too fast or overwhelming.

Gen was looking Senku in the eyes, something the scientist wasn't used to, and something about the mentalist's gaze was reassuring. As if his top priority was Senku's pleasure and Senku's pleasure alone.

"Ready," Senku said.

Gen leaned forward and pressed his tongue against the tip, giving it a swift but firm swipe Senku gasped, an involuntary reaction. Gen responded by pressing a kiss to the same spot. While it didn't feel as good as the previous action, it still felt fairly decent.

Gen moved his head down and flattened his tongue against the base of Senku's cock and dragged it up to his tip. Senku groaned. Gen's tongue was so soft and wet. Senku could feel the saliva cooling on his skin, and it was a wildly uncomfortable sensation.

Gen wrapped his lips around the tip and then pulled off. Senku was both grateful for this slow pace and tortured by it. He wanted to feel more, to know what it felt like, but at the same time, he didn't know if he could handle Gen's maximum skill yet.

"Gen, can we speed this up just a little bit?"

"As you wish, dear Senku."

Senku was about to explain his request, because for some odd reason he felt the need to, but his words and his breath were halted in his throat. Gen had wrapped his lips around the tip. It was better than anything Senku had ever felt. It was a warm, wet, humid cavity surrounding one of the most sensitive parts of his body.

Gen laved his tongue over the slit and Senku gasped loudly. He was glad that they were alone in the apartment, because he had a feeling he would be getting a lot louder as this went on.

Gen began a slow descent down the length of Senku's cock. It was heavenly, and Senku never described anything in such an un-scientific way. It was ten billion percent amazing.

Senku watched Gen, who was obviously enjoying himself, and found it only got him more excited. However there was one thing that worried him.

"Are you sure you can... Take it all? I don't want to... Hurt or... Strain you..." Senku panted. Gen pulled off, much to Senku's dismay, and smiled at him.

"Are you doubting my skills, Senku?"

"No, I just..." Care.

"No need to et-fray, silly scientist, I'm a pro at this."

"A pro mentalist and a pro at head giving? What a combination."

"I'll prove it to you," Gen slid back down and swiftly took what was easily half of Senku's cock into his mouth. And embarrassing whine escaped Senku's throat, and Gen looked quite pleased with himself.

Gen swallowed around the part he held in his mouth.

"Oh fuck-" Senku gasped. His fingers tightened around the arms of his chair.

Gen saw this and gave the most list filled look his face could make in that position. It was one of the hottest things Senku had ever seen: Gen giving him a look that said he was planning so much more, while holding Senku's cock in his mouth.

Gen started to slide down, taking another inch into his mouth. Senku's breath was shaky and deep. Gen shifted his position, and Senku's cock, to get a better angle to take the rest of it down, all the way to the base. Senku moaned loudly; his whole cock was now engulfed by Gen's exhilarating mouth. Gen waited in place, still staring Senku in the eyes.

He nodded, signaling to Gen that he could start moving, but Gen didn't start moving. Instead, he moved his tongue up and down the whole length of it from the inside, causing Senku to moan. He felt Gen's tongue go from the base up to just under his tip and back down again. How flexible was this guy's tongue?! Then Gen sucked, actually sucked, on his cock, and Senku decided that it didn't matter right now.

"Do that again," Senku muttered.

Gen repeated the action.

"Oh fuck," Senku brought his hand up, hovering it just in front of his mouth, "keep doing that... Please."

Gen complied and sucked on his cock repeatedly. At first it was a slow rhythm, then he sped up, sucking in short, consecutive bursts. Senku preferred the faster pace; it had him panting hard. He was sure it was due to his inexperience, but he was so fucking sensitive. He pushed his hips up into Gen's mouth. Then he did it again, and once more. The movement felt so good, even just one millimeter.

Of course, the mentalist himself understood this immediately. He stopped sucking and started moving his head up and down Senku's length. Senku clasped his hand over his mouth and shut his eyes tight. Gen tugged on his arm and pulled his hand off his mouth. Senku reopened his eyes, just barely.

"Yeah? You wanna hear me?" He asked. Gen's eyes gleamed in response, since his mouth was occupied.

Senku watched – and felt – Gen's head moving up and down his cock. He was amazed that the mentalist could take it all, with some of it literally in his esophagus, and even more amazed by how it felt. He couldn't stop himself from moaning loud enough for it to be heard through the walls.

All of a sudden, Gen added a new trick into the mix. He started to swipe his tongue across Senku's tip on every upstroke. Senku whined almost pathetically. He couldn't help it, it was so sudden and felt so good.

"Holy fffuck, Gen... You're really fucking-" he was cut off by a moan escaping his lips, "shit. You're really... Pulling out all the stops here, huh?" He unconsciously pushed his hips further up into Gen's mouth.

Gen hummed around him, which probably would've been a singular laugh, had his mouth been free. Senku figured that Gen had plenty more tricks up his sleeve, and he wasn't about to object. He had gotten excited. He wanted to know how good Gen could make it. Senku moved his hand down, then stopped it to hover right above Gen's head.

"Can I?" He asked breathlessly. Gen nodded as best he could, but that small nod was all Senku needed to allow himself to grasp the back of Gen's head, perhaps a bit too roughly. He could feel the roots of Gen's hair being pulled up into his grip. He was worried he might be hurting the mentalist, but then he saw how Gen's eyes were rolled slightly back, when previously they had been locked onto Senku's face. God, how hot could one man get? Apparently ten billion times hotter, exponentially.

Gen's tongue started dancing around Senku's cock and it felt like pure bliss. Senku moaned Gen's name without restraint.

"Gen! Fuck!"

Gen became even more vigourous. Then, Senku felt Gen's soft, smooth fingers curling around his balls. Senku choked on a gasp. Those dexterous fingers felt like magic as they rolled and massaged Senku's sack.

The dual stimulation from both Gen's mouth and hands, had Senku barely able to speak. All his words came out broken, if at all.

Of course, Gen loved this. He started almost literally gulping down Senku's cock, and never stopped bobbing his head or rolling his fingers.

Senku's breathing sped up to multiple breaths a second. It felt too good. He could feel his lower abdomen heating up and tensing to the point that it was almost painful. It meant he was about to orgasm, but it had never felt this intense.

"Oh- f-fuck-" he could barely speak, he had to force the words out quickly, "GenI'mgonnacumI'mgonnafuckingcum!"

His abdomen felt incredible light as it intended when his orgasm hit him like a truck. He shoved Gen's head down and held it against his pelvis. The hot spurts of cum shot out of his cock and down Gen's throat. Gen swallowed every millimeter of it with ease. He sucked it down and with every suck it prolonged his orgasm. Eventually, after what felt like ten billion years but was probably just twenty or so seconds, it finally stopped. Gen's throat was still moving and it was way too much.

Senku yanked Gen's head off and the other was pliant enough under his grip that he moved up without any resistance. Senku's wet cock slipped out of Gen's mouth and landed on his thigh with a wet slap.

Gen had a self satisfactory grin on his face as he watched Senku panting while trying to recuperate.

"I bet you're just so proud of yourself, aren't you?" Senku panted. Instead of responding, Gen opened his mouth and stuck his tongue out to show Senku the thin, sparse coating of his semen that still remained in Gen's mouth. Senku felt himself blushing even harder because of the erotic display.

Gen closed his mouth, swallowed, and finally responded, "I don't know, should I be?" He gave Senku the best 'puppy-eyes' look he'd ever seen and raised his voice a pitch, "Did I do good?" Senku scoffed and shoved Gen's head back with a playful push to his forehead.

"Do you really need me to tell you that? I came, didn't I?"

"Yes, you did, and you lasted much longer than I thought you would, being a virgin and all. But nevertheless, I need to know if my erfomance-pay was satisfactory," he leaned forward and switched his puppy eyes to a sultry glare, "Did it leave you awe-struck?"

Senku laughed, as best he could manage, before responding, "Yeah. You did wonderful. That was ten billion percent better than I expected."

"Good. I did my job well, then."

"You definitely gave a great show, along with great head," Senku was finally starting to get his breath back.

"Shows are what I'm best at, my dear Senku."

"I'm well aware. Now could you grab one of the towels over in that bin," he pointed in their general direction, "I can feel your saliva cooling down on my skin and it's really uncomfortable."

Gen nodded and grabbed a towel. Then he returned to his place below Senku's desk and began to clean the scientists groin and inner thighs. Gen grabbed hold of Senku's cock and for a second he thought Gen was going to jerk him off, but he just tucked it back into his pants and zipped them back up.

"I could've done that myself, you know. It is 𝘮𝘺 dick," Senku said.

"That I just had down my throat."

"I could've still done it myself, I wasn't incapable."

Gen rested his head on Senku's thigh, "It's called aftercare, Senku dear. It's what you do after sexual activities to make sure the other person doesn't feel used or alone."

"Of course the mentalist knows that."

"It's pretty common knowledge."

"Shut up. No it's not."

"I'm not surprised you weren't aware; you're pretty inexperienced in the world of ex-say."

"Whatever. Just get up off the ground, I'm tired of looking down at you."

"I'm hurt, Senku dear. I thought I looked great on my knees for you," Gen whined, but he got out from under the desk without any real protest.

"Sure, Mentalist," Senku wasn't about to tell Gen that he really did look beautiful down there.

"Aww, we're back to Mentalist now? I liked Gen," he whined.

Senku scooted his chair forward so he was close to his desk once again, "Shut up and get yourself a chair to sit near me."

"As you wish," Gen said, and left the lab-room to go find himself a chair.