Posted originally on the Archive_of_Our_Own at https://archiveofourown.org/ works/8957401. Rating: Explicit Archive Warning: Underage, Choose_Not_To_Use_Archive_Warnings Category: M/M Fandom: モブサイコ100_|_Mob_Psycho_100 Relationship: Kageyama_Ritsu/Kageyama_"Mob"_Shigeo Character: Kageyama_"Mob"_Shigeo, Kageyama_Ritsu Additional Tags: Incest, Sibling_Incest, Angst, other_sensitive_content_not_mentioned_in tags Stats: Published: 2016-12-22 Words: 3059 ****** Trompe L'Oeil ****** by leifmotifff Summary After a long day, Ritsu just wants to lay back and unwind. Luckily there's something waiting for him at home that can help. Notes Hi there! Please make sure you're comfortable with potentially problematic themes before continuing. Thank you! See the end of the work for more notes Ritsu shuts the front door, leaning back against it with a sigh. It had been a long day—or at least, it feels like it had, now that it gets dark so much earlier. Ritsu is a lot crabbier in the winter months; days like today, when it isn't raining, but just bitingly cold, are the worst. Thankfully, he has most of the evening free to unwind. He flips the light switch on, pausing to stretch before walking through the living room towards his room. “Nii-san, are you home?” he asks as he turns the door handle, pushing it open. Light spills into the darkened room, just in time for him to see Mob stir under the covers. His brother turns towards him and blinks his eyes open, rubbing at his face a bit before sitting upright. “Oh hi, Ritsu. I was just napping.” When he looks over at Ritsu though he doesn’t look the least bit groggy, like maybe he wasn’t actually sleeping. “Sorry, Nii-san. Are you tired?” Ritsu asks, laying his bag down on the chair by his desk and turning on the lamp. Mob shakes his head. “No, I’m not. But I missed you.” He smiles, scooting down a bit on the bed and patting the now vacant spot next to him. “Come sit and talk with me.” The corners of Ritsu’s mouth quirk upwards. Just being with Mob is usually enough to put him in a better mood. He shrugs off his coat, draping it on the same chair, and Mob’s eyes crinkle into happy little half-moons when Ritsu takes the few steps across the room to sit next to him on the edge of the mattress. “What do you want to talk about?” Mob swings his legs up to sit on his shins. It gives him a bit more height next to Ritsu, who even sitting down is still several centimeters taller than him. While Ritsu has grown, Mob has stayed the same. “Whatever you like,” Mob says placidly, bringing a hand up to stroke the back of Ritsu’s head, above the nape of his neck. He knows Ritsu likes feeling his small fingers on his scalp. Ritsu inhales deeply, leaning his head on Mob’s shoulder. He reaches around Mob’s back to lay a hand on his hip, and they sit in silence for a moment, side by side. “To be honest, today was kind of stressful. I think I just want to relax a bit.” His fingers brush lightly against Mob’s skin, teasing under the hem of the thin t-shirt he’s wearing. Mob recognizes cues like that. The hand stroking Ritsu’s hair slides down, fingers going to his jaw, to turn Ritsu’s face just slightly towards him. “I can help with that,” he says quietly, and waits for Ritsu to lift his head just a little, to meet him in the middle, the barest press of lips. It’s not enough, though. It’s never enough, and after just a few seconds Ritsu’s free hand reaches up to cup Mob’s face, to press their mouths more urgently together. Even when Ritsu is trying to take it slow, it’s usually not long before he’s gripped by need, like he’s not used to this yet—having Mob, here with him, like this—like he’s afraid it’s not going to last. His fingers splay against Mob’s hip, and although they must still be cold from the air outside, Mob doesn’t squirm or flinch. Instead he responds to Ritsu’s neediness with his own, opening his mouth to let Ritsu’s tongue in. They kiss like that for a bit, Ritsu’s cold hands running down Mob’s chest, pressing hungrily against the soft fleshiness of his stomach. Mob has yet to get rid of his baby fat, despite his modest gains from his school club. Ritsu unconsciously pulls the slighter boy more and more into his lap as they paw at each other, and Mob finally breaks the kiss, seemingly for air, but mainly to adjust his position so that he’s less at risk of losing his balance.   “Here,” Mob says breathlessly, licking his lips before looking up at Ritsu from under the curtain of his bangs. “Lean back.” He presses a palm gently against Ritsu’s shoulder, though not enough to actually push him—just a suggestion. Ritsu is all too happy to comply, and he lays back gingerly, letting out a tiny gasp when he moves his legs up to spread out on the bed, the inside of his jeans rubbing awkwardly against his growing hard-on. Mob crawls over him like a cat, hands and knees coming down delicately to bracket his body, and Ritsu takes a shaky breath as Mob looks down at him, smiling that tiny, serene smile that never fails to make Ritsu’s insides squirm, even after all these years. Ritsu’s fingers twitch at his sides, eager for some part of his brother to grab onto, and he feels for Mob’s legs, hands curling around the back of his thighs, just above the bend of his knees. His breath quivers in his lungs. Mob is still so soft… so small. “Relax,” Mob whispers. He says it so innocuously, but the way he drops another light kiss against Ritsu’s parted lips, licking gently into his mouth, teasing him just enough so that when he pulls back, Ritsu lifts his head off the pillow to chase it... he promises so much more. Dark heat flares in Ritsu’s belly, and his cock strains even more against his pants. No fourteen-year-old should know how to do that. Mob exhales, a pleased little sigh, and he pushes Ritsu’s shirt up, exposing his more developed chest. He leans down to press kisses against his torso, licking and nibbling his way down Ritsu’s body. Ritsu’s hips are already twitching, and his restless hands come up to cup the back of Mob’s head, threading his fingers through silky hair. Mob laps docilely at his right nipple, and it’s so sweet, so gentle, but Ritsu is already worked up. It’s embarrassing—no matter how many times they do this, it still feels like it’s the first time—like it might be the last time. “Nng—Nii-san—” Ritsu starts, aimlessly. Mob immediately releases the bud of his nipple with a small smacking sound. “Okay,” he answers unquestioningly, before moving a little further down the bed. He makes gentle work of Ritsu’s fly, careful not to rub abrasively where his cock is pushing against the denim. Mob tugs Ritsu’s pants off and tosses them to the side before focusing on his boxers, the cotton fabric pulled into a terse tent. He wriggles into the cradle of Ritsu’s thighs, running his hands up bare legs before gracing him with an almost coy glance. “Ritsu, is this all for me?” Mob’s voice is as inflectionless as ever; he might as well be talking about their mom’s leftover curry in the fridge, but the mundanity of it somehow just makes Ritsu feel even dirtier, like he’s the only one getting off on what they’re doing. Which really, he is. “Yes, Nii-san, please, just—ahh—” He’s cut off by his own moan when he feels Mob’s warm mouth around his clothed cock, the cotton of his underwear quickly becoming saturated with both humidity and saliva as Mob licks and sucks around the shape of it. Ritsu whines, and Mob draws off the wet cotton, licking his lips again. “It’s okay, Ritsu,” he says in that same, sedate tone. “I want to taste you, too.” He peels the damp underwear off, watching indolently as Ritsu’s twitching cock springs out, the head shiny and drooling pre-come. Mob wraps a pale hand around the base, and Ritsu’s own hands grip the sheets as he struggles not to buck up, his thighs spreading wider. They’ve barely even done anything and Ritsu is already panting, desperate. Mob finally lowers his mouth over Ritsu again, and that raw wet heat is enough to make Ritsu groan, one hand moving again to the back of Mob’s head to tighten around a chunk of his straight locks. But Mob doesn’t complain, doesn’t even make the faintest acknowledgement of the rough tug at his hair. He just licks around the flushed head, pushing his face down to take Ritsu as deep as he can before pulling his lips back up again; wet, slurpy noises competing with Ritsu’s increasingly pathetic whimpers. “Mmnn, Nii-san,you’re—so good at this—hhaa…” Mob answers with a twist of his wrist and a low hum, and Ritsu’s eyes go wide at the resulting vibrations along the length of his cock. He can’t help it, his hips jerk, and he lets out a choked moan when he feels the tip of his cock hit the back of Mob’s throat. Mob makes a small gagging sound, but he doesn’t draw all the way off, just uses his hand to stroke up and down the slippery length while he continues to suck at the tip, breathing harshly in and out of his nose, and Christ. Ritsu’s not going to last long. “Ah—ffuck—I’m—I’m going to come soon,” he wheezes out, the pressure building between his legs. It’s taking everything in him to keep his hips against the mattress. Mob releases his cock from his mouth, sucking in some of the saliva with a lewd wet sound. He trails his lips around the head, pressing soft kisses all around it, and glides the hand gripping Ritsu’s cock down to squeeze gently at his balls, rolling them between his fingers. “So come,” Mob murmurs against his cock, dipping his tongue into the slit. Ritsu keens, looks blearily down at his brother. Mob is staring up at him through half-lidded eyes. “Do what you like, Ritsu,” he repeats quietly, kissing delicately against the frenulum before closing his lips over the head again, and Ritsu’s body is fire, fucking, impossible fire, and he lets out a hoarse groan before both hands move to Mob’s head and slam down, forcing the entire length of his cock down his small, tight throat. Ritsu’s hips thrust viciously in and out of that heat, those soft, swollen lips dragging devotedly along his pulsing hard-on as Ritsu fucks his brother’s mouth, and Mob is so compliant, limp, a doll. “God,Nii-san—” Ritsu’s voice goes high-pitched, breaking on the honorific, and it’s like a magic word—Mob swallows, hard, and Ritsu’s cock throbs as he’s squeezed by the satiny inner walls of his brother’s throat. Ritsu’s back arches and he cries out as he shoves Mob’s head down one final time, gripping his hair so tight, muscles locking up as his orgasm hits, toes curling as he empties himself down Mob’s throat. Mob swallows it all obediently, letting Ritsu ride it out with his cock still stuffed in his mouth, moving his hands down to rub gently against Ritsu’s trembling thighs. He only makes to draw off when Ritsu’s grip in his hair loosens, tingling fingers stroking shakily against his scalp. Mob presses a small kiss against his hip before shifting up the bed to lie contentedly next to him, snuggling between Ritsu’s arm and his side. Ritsu has barely begun to soak up the afterglow when he hears a buzzing sound from somewhere on the floor. He squeezes his eyes shut tight, scrubs the hand not cradling Mob across his face before reaching down with a sigh to fish his phone out of his discarded pants pocket. He lifts his head just a bit to peer over the edge of the bed. The name “Shigeo” blinks across the display. Ritsu slides his finger across the screen to answer, a vaguely uneasy knot curdling in his gut. “Hello?” “Hi, Ritsu,” his brother’s voice intones through the slight static. “Are you still good to meet at seven tonight?” Ritsu blinks, glancing at the clock on the wall. “Ah, that might be kind of early for me, actually.” “That’s okay,” Mob answers. “I figured you might have to work late. Listen, is it okay if Tome-chan brings someone? It’s her co-worker from the aero-space agency. She’s supposed to be really smart, and she’s your age. Actually a little younger, I think.” Ritsu sighs loudly without meaning to, and almost immediately feels guilty because Mob is quick to say, “Don’t feel like—it’s okay if you say no. I know it’s not always nice to have company sprung up on—” “No—sorry, I didn’t mean... Sorry. I just had a long day at work.” Ritsu wavers half a second, before giving in. “Of course she can bring her friend… I’d love to meet her.” He forces a fake smile out of habit, even though Mob can’t see it. Though even if he could, Mob would probably see through it. Unsurprisingly, he can hear Mob’s hesitation on the other line. “Are you sure? If you’re tired, it’s okay, we can—” “Please, Nii-san, it’s fine,” he insists. “I want to see you.” “Ah, alright. What time sounds good, then, seven forty-five?” Ritsu closes his eyes briefly, assessing. That’s enough time to shower, clean up his apartment in case Mob comes over after dinner like he sometimes does. “Yeah, that works.” “Okay, let’s meet at the restaurant then. See you soon, Ritsu.” “Bye, Nii-san.” He hangs up and tosses his phone back on top of his jeans, dropping his head back heavily onto the pillow. The presence next to him shifts slightly, all but forgotten during the brief phone call. “Was that your other Nii-san?” a small voice asks. Ritsu turns to look at the Mob bot. A jarring anachronism, the spitting image of his brother at fourteen stares curiously back at him. “Yes, I’m going out to dinner with him later,” Ritsu answers kindly. He sits up on the bed without sparing any other niceties, however. Too often after having sex with the bot, he lays there with it, breathing its artificial Mob scent, kissing its tiny, manufactured lips, blurring the lines between imagination and existence. The company that creates the machines actually warns against that sort of thing when you go in for a consultation, even administering a psych evaluation to all potential buyers before allowing anyone to make a purchase. But some days… it just seems so real. Of course, it’s all artifice, Ritsu knows, evidenced first and foremost by the lack of free will: though it seems like the bot is making its own decisions, every action it takes has been pre-encoded based on specific personality and behavior preferences Ritsu himself picked out. That, and the fact that it can never make Ritsu do something he doesn’t want to do—unlike the real Mob, who’s about to drag him on another blind date with someone Ritsu is positive he won’t have any interest in. He never has any interest in them. What he does have is this. His biggest indignity, one that he would literally die to keep secret. Luckily, this technology isn’t yet widely produced—it isn’t even really advertised, except to the extremely connected, and the extremely wealthy. Ritsu just conveniently happens to be friends with both. Even so, no one knows about it. Only he and the team who designed it are aware of the existence of the Mob bot. Which, actually, he thinks, is due to be serviced sometime next week. Get its fluids refilled, software updated—whatever else they do to maintain the deception. Ritsu stands, legs a bit tingly from the imitation teen blowjob. He’s only had the thing for three months, but he practically can’t even tell the difference anymore. He picks up his jeans from the floor and tugs them on sloppily, if only to shield him from the slight chill in the room, now that he’s no longer brimming with arousal. He should turn the heater on before he gets in the shower. He utters the code phrase to trigger the Mob bot to put itself away and power down. “You’re probably tired, Nii-san. You should get some rest.” There’s a brief pause as the machine registers the command. “Yes, I think I will,” it responds tranquilly, and Ritsu feels movement behind him as it climbs gracefully off the bed. He startles a tiny bit when it reaches for his arm, but the little Mob just squeezes his hand affectionately and looks up at him through familiar half- moons. “Goodnight, Ritsu,” it says warmly, and still—still, its small, sweet smile is too much for him to resist. Ritsu bends to kiss it chastely on the lips—so much shorter than him, the height difference so much greater than he and Shigeo ever had growing up. “‘Nii-san,’ huh? Are you sure?” The behaviorist had asked him wryly, his eyes flicking from Ritsu to the prototype on the screen. No one had batted an eyelash at the request for a minor equipped with the full arsenal of sexual comportments, but a twenty-eight-year-old calling a robot with the appearance of a middle school boy ‘older brother’ apparently required explanation. Ritsu buries his face in the false skin of the bot's neck, fingers sliding through its glossy hair, pressing the small body close again. His eyes fall shut, and he breathes deep. It’s almost like... Almost like that brief period when they were young, when Shigeo had let him do what he wanted. Before he had figured out that their inexperienced fumbling meant something different to Ritsu than it did to him—meant something else entirely. Ritsu would never have that again—those fleeting, heavenly few months when his brother’s beatific innocence had allowed him to indulge what no one else would ever accept. He would never have it again, but he would hold onto that memory forever, as timeless a recreation as he could get. Ritsu feels himself trembling, emotion welling behind his eyes, and he abruptly lets go of the machine. He turns away when he hears it moving routinely to open his closet, and he leaves the bedroom to start the shower. It’s always disturbing seeing what looks like another human step into a charging pod. The Mob bot doesn’t know any better, though. Its synthetic eyelids descend over its lenses, face relaxing into a default neutral expression, ready to recharge, to stand by—peaceful, purposeless. Waiting dutifully until the next time it registers its owner’s initiating command.   “Nii-san, are you home?”   End Notes ｡：ﾟ(｡ﾉω＼｡)ﾟ･｡ I got this idea about ten minutes into the first episode of HBO's Westworld... Please let me know what you think! Thanks for reading! Find me on twitter @leifmotifff for more brotherfucking!! Please drop_by_the_archive_and_comment to let the author know if you enjoyed their work!