When you think about it, this is all Mob's fault anyway.
He was supposed to be away at university, and yet he'd turned up on your doorstep late last night like a lucky penny, all shined-up and new and sweet. You half-thought you were dreaming until he'd pulled you into a hug, mumbling about how he didn't have any coursework that needed doing and he'd missed you, i missed you so much arataka-san.
That was strike one.
Strike two was waking up to Mob clinging at you like a limpet, his breath in your ear making you shiver, and his morning wood right on your ass. You'd tried to squirm away and in the process ended up rutting against him, which felt so unbearably good. And then he moaned, shifted even closer until he was slotted between your thighs, and did a lazy thrust of his own that nudged your balls and made your eyes roll in your head. Panic overcame the wrestle with lust. You catapulted out of bed and into the bathroom before Mob could wake up all the way and see how hard you were.
And now. Now. Him sitting here in your office for the first time in a long while, like he hasn't left at all. High and bright sunlight striping across his face as he reads manga at the desk that used to be his. The two of you alone together, just like before, except Mob is taller than you now, and broader, and his small, blushing smile when he realizes you're staring at him has you aching with more than fond affection.
You've officially been together for almost a year now, and yet you've done nothing more than hold hands, steal messy kisses, explore over clothes, and, a few months back, Mob had rubbed you both off in your apartment, Mob moaning your name over and over like he'd die if he stopped.
The age gap is complicated. The long-distance relationship sucks. The fact that Mob has steampowered his way into your heart with sheer bloody singlemindedness despite both problems, and that he's now close enough to touch after so long apart— well.
No clients ever come around this early in the day anyway.
He looks up when he notices you walking towards him, and he has a winsome, neutral face on, except he betrays himself by glancing at your lips.
Strike. Three.
You kiss him without so much as a by-your-leave, your knee hitching up on its own to crowd between Mob's legs on his seat. He's frozen for a second, perhaps surprised because you don't often initiate kisses, especially ones this intense. Then he starts responding with equal fervor, tipping his head to the side and opening his mouth. You push your hand under his shirt collar, the sea green shirt that you'd gifted him years ago, which he still loves wearing even if it's getting too small for him, simply because it was you who gave it.
Damn this boy, this man. You want him in every way there exists to want a person. But earth-shattering kisses will have to do until he's ready for more.
Some small amount of time passes, heat and movement and Mob's tongue dragging against your own, and you somehow find the fortitude to pull away from him. He chases after you as you do, eyes still shut and face scrunching up in an adorable not-pout.
"Well!" You clear your throat and try to regain your composure. "Um, that's. Thank you, for being here. I'm. I missed you to, Mob. I don't think I'd said that yet so I'm saying it now." You grin down at your shoes and nod. "Yep, okay, that's all." You turn to go, but Mob grabs your hand, quick and tight as a viper.
You've never seen him like this before, heavy-eyed and bewitchingly dark. "I want more this time." He runs his thumb over your wrist, and whispers with a strange glee, "Reigen-shishou."
You jerk away, or at least try to, the tips of your ears burning. Mob's grip doesn't slacken in the slightest. "Jeez, I thought we agreed you'd stop calling me that. I'm not your master anymore."
"You're right," he agrees. "You're not." With slow, sure movements broadcasting his intent, Mob begins unbuckling his belt with his free hand, popping the buttons on his fly. You flush hot and rip your gaze away to his face, except looking there is worse, his eyes pinning you like a butterfly to corkboard. He must see how torn you are, because he stops, softens, becomes less lion and more lamb, the one you're more accustomed to dealing with.
"Um. Is. Is this okay? I'm sorry, I'm getting carried away—" Even as an adult, he's still too kind for his own good. And yet this new side of him that's crept out, this confident, insistent side— you want more of it. More of him, his new dimensions and spaces. You want to learn all of him. And that is what crumples you to your knees.
He gasps, soft but audible. "I like it," you admit, your gaze flitting from the tent in his pants to his pleasantly surprised face. You let your lips curl into an open leer. "Do you worst."
Once again, Mob hesitates for a second or two, until his desire takes over. "Okay then." He unzips and pushes down his boxers just far enough. "Get to work."
You gulp at his calm demand, his display of control. You shuffle forward and rest your hands on his thighs, strong and firm from years of running. You're getting hard yourself from seeing him in proper light for the first time, thick and beautiful like the rest of him. After some warring with yourself, you look back up at him and his darkdarkdark eyes, and say, "Tell me what to do."
Mob hums, leans back in his chair. "Kiss it."
That authoritarian tone of voice again, making even more of your blood migrate south. He doesn't even look phased, like it's a regular day, save for the light color in his face and the fact that he's hard enough to hammer nails. You kiss the head of his cock, down his shaft, affectionate brushes that make him twitch.
"Open your mouth."
You can't hide your shiver, and you do as he asks, but decide to fuck around a little, panting hot breaths and borderline drooling mere centimeters above him. "What now?" you chuckle.
"Now you suck it and make me feel good."
You utter a tiny sound, and quickly unzip yourself for some relief, already this worked up from his mere words alone, when he hasn't even touched you. "Disclaimer, I haven't done this much," you manage to banter, before taking as much of him as you can into your mouth.
He hisses and sighs, and you take it as encouragement, doing your best to coat your teeth with your lips, swirl your tongue. You take breathers every half-minute, relaxing your jaw while you keep him occupied with your hands. Mob sits back, wordless, drinking in the sight of you. At some point, as you bob your head up and down, he tangles his fingers in your hair, and your toes curl in your shoes a little at how nice it feels.
And then you hear footsteps and voices down the hallway.
Mob does when you do too, and he's panicking, telling you, "Wait, it isn't locked—"
The aforementioned doorknob is already rattling, turning. Once again, you panic and escape a situation you don't know how to control; this time by squishing yourself under his desk.
He glares down at you, and then suddenly, a smile. You're unnerved, and try to deduce what that means before he drags his chair into the desk to hide his unzipped pants and erection. Which means he's crowding you, boxing you in with his legs. You stifle a groan of frustration and try to shuffle around on the floor to get comfortable.
"Hello, is this Reigen Arataka's office?" A man's voice, one accustomed to getting his way.
"Yes, this is. I'm his student. He's out for the morning but if you wish to discuss your troubles I will take note of them and convey them to him, and we can follow up with you." Mob is polite, friendly, professional. You would be proud of him overcoming his social anxiety but your back is killing you here in this tiny space.
"See, Dad? Told you this place is legit." A young girl, a teenager, the hasty clicking sounds of a phone keypad. "They have really good reviews, on top of it being cheap."
You huff, and listen in. The clients are a father and daughter who say their house is haunted. Mob appeases them, inquiring details about the situation, the family history, saying how the two of you would come by this afternoon to investigate the place. You try to concentrate, but you're getting distracted. This close, Mob's right there, still half-hard and glistening from your spit. And he's so warm, and the scent of him addling your inhibitions.
Then Mob's hand reaches down and gestures the universal come hither motion.
It's a terrible idea. Heinous. Despicable. You could get caught any second, your business ruined, your reputation besmirched (again), Mob expelled from university, the both of you labeled disgusting freaks.
You're so hard it hurts.
You're discovering way too many things about yourself in a single morning. But it's okay, Mob is just telling you what to do, so you should do it.
You close your mouth around him and something bangs on the desk above your head.
"Are you alright, young man?"
"Yes, sir, just a little under the weather. Body pains."
"Hm, boss working you too hard? What do you even do for him, when you're a student?"
"Ah, well." Mob goes on to detail the exorcisms and services the office does, talking like nothing's wrong, like what you're doing to him is inconsequential.
His hand finds your face, calluses from a decade of weightlifting scraping and digging into your cheek, fingers curling to grasp the back of your neck.
Mob pushes your head back and you think it's to make you stop, but then. But then. When nothing but the tip of Mob's cock rests on your tongue, your head is pushed right back, almost to the root, your nose brushing his dark curls there. You go cross eyed from trying not to gag.
And then Mob pushes your head away again, and draws it back, and you realize what Mob is doing to you. Your mouth is just being used as a fleshlight. Your mouth is no better than an inanimate toy existing for the sole purpose of getting Mob off.
You can't help the low whine that builds in the back of your throat, your own neglected dick twitching and soaking your briefs.
Mob's still talking. "Yes, I've worked under Reigen-shishou for quite a long time. I've learned so much from him." As he says it, he draws you in and holds your head in place. You can't breathe as your throat flutters around Mob's cock. His calm finally cracks, and he husks out, "Shishou's very good to me."
Gods almighty, you're not sure if you're going to cry or cum in your pants or pass out, or all three. It's all too much and too good.
At last, at last, the clients take their leave. The moment the footsteps outside recede, Mob straight out growls, grabs your skull with both hands and thrusts mercilessly once, twice, and cums. You can barely even taste him; it all goes straight down the back of your throat. He releases you and drags his chair away. You crawl out from under the desk, and you cough and hack and wheeze and shake, like you're being born again. Maybe you are.
"You okay?" Mob rasps, like his throat's the one that was used as a cockwarmer and not yours. "Shit, sorry if I got carried away."
"Mob." Your ruined voice clams him up. "If you don't touch me right now I'm gonna have to go home and change my pants." You're so aroused you're trembling, drunk on the sensations and wanting more.
"Ah." Mob's wide worried face turns into a smirk, whiplash of a transformation and you're still too lightheaded for this.
Mob drags you to your feet, spins you around to face the desk and bend you over it, your chest flat against the surface. You're not even given time to find your balance. He unbuckles your belt, drags your pants and underwear down to your ankles. He's the one who kneels now, to lick your balls, your taint, your puckering hole. He spears you open with his tongue and jerks his spit-slick hand on your cock, fast and rough, devouring you all over. You wail and cry, oscillating between thrusting into his fist and pushing your ass back on his face. Within minutes it's over for you, rush and glory and all, spilling between Mob's fingers.
You still can't breathe right. You're turned to jelly. A jelly with aching knees and a sore back and a swollen jaw and a stomach that hurts from being poked by the edge of the table, but still somehow formless. Mob scoops you up and he sits back on the chair, settling you in his lap to rest.
"You okay, Arataka?"
"Guh," you croak, blinking up at the ceiling, completely winded. "You fucked my face."
"I know."
"In front of clueless people."
"I know," he repeats, smug this time.
You kick the side of his leg with your own that's draped over his. "We are never fucking doing that again," you groan.
"I know." Gentle, reassuring, apologetic. A little lamb again.
To take the sting out of your words, you add, "The rest of it? I. I liked. I liked a lot of that. All of that." You mull over it. "I guess I just like you."
He chuckles, and cups your jaw to turn your face so he can kiss you, feather-soft. "I love you too."