Posted originally on the Archive_of_Our_Own at https://archiveofourown.org/
works/8166604.
  Rating:
      Explicit
  Archive Warning:
      Underage
  Category:
      M/M
  Fandom:
      モブサイコ100_|_Mob_Psycho_100
  Relationship:
      Kageyama_Ritsu/Kageyama_"Mob"_Shigeo
  Character:
      Kageyama_Ritsu, Kageyama_"Mob"_Shigeo
  Additional Tags:
      Incest, Sibling_Incest, Masturbation, Unresolved_Sexual_Tension, some
      dub/non-con_themes, teen_angst_lol
  Stats:
      Published: 2016-09-30 Words: 3013
****** Toxic Boy ******
by leifmotifff
Summary
     Ritsu deals with his inferiority complex and conflicted feelings
     towards his brother.
Notes
     Kind of a character study? With some sad solo masturbation thrown in
     for good measure? (●´ω｀●)ゞ
     Takes place around episode 6 of the anime/chapters 20-24 of the
     manga.
See the end of the work for more notes
The bell signifying the end of classes rings, and the sound of rustling papers
and chairs scraping the floor fill the room as students begin to chatter and
gather up their things. Ritsu bids goodbye to a couple classmates before
passing some of the gang members whispering in a huddle on his way out.
He ducks his head, frothy guilt bubbling up in his chest. He knows what he and
President Kamuro did to Onigawara is despicable... but if that’s what it takes
to stop those thugs from picking on his brother, so be it.
As soon as he steps outside he spots Mob across the lawn, already exiting the
gates of the school. Mob turns left at the sidewalk instead of crossing the
street, so he must be going to that hack’s office downtown for his afterschool
job. Ritsu on the other hand has a rare block of free time: Vice President
Tokugawa had told them earlier that the Student Council meeting would be
cancelled that afternoon, so he makes his way back towards their house, the
late summer humidity relentless around this time of day.
Once home, Ritsu sets his bag on his desk and takes out his notes to review for
the biology quiz tomorrow. It’s mostly pointless, as he already memorized the
material over the weekend, and he wanders idly back out into the hallway before
changing his mind. He doesn’t feel like hearing the noise of the TV right now,
either.
His gaze falls on Mob’s bedroom door, slightly ajar, a stripe of daylight
peaking through into the dark hallway. For some reason, Ritsu’s compelled to
push it open. He feels a tiny bit bad about going into Mob’s room when he’s not
there, but Ritsu’s a bad kid now, anyway, so maybe it’s not so surprising that
he gets a strange thrill out of being in there without permission.
There’s nothing particularly remarkable about the room. Mob doesn’t really have
any interests, so his walls aren’t adorned with any posters or memorabilia. It
smells like him, though: that clean, white bar soap and milk, and something
fresh—oh, the new deodorant he’s started wearing since joining the Body
Improvement Club. Ritsu had caught a glimpse of the group jogging around the
track the other day; Mob had been trailing behind the rest, and it wasn’t long
before he stopped running and doubled over, hands on his quivering thighs, red-
faced and chest heaving as he tried to catch his breath.
Ritsu clenches his hand unconsciously into a fist. How could Mob be so
wholesome, trying in earnest to improve himself physically as if he were any
average person, when in reality he has the ability to harness unspeakable
destructive power?
That must be the difference between us, Ritsu supposes austerely. Though, he
has seen flashes of darkness in Mob as well.
Obviously, there was that time when they were children, on New Year’s, but even
now, every so often Ritsu will sense something slightly off with his older
brother. He always tries to reach out to Mob in those fleeting moments, to lend
a compassionate ear, see if he’ll finally open up.
He’s watched silently as Mob has withered in adolescence, becoming unassuming
and self-effacing, unfazed by most things, his emotions dulled down like shards
of glass weathered for years at sea.
It makes him sick.
Deep down, under all his layers of self-preservation and emulated indifference,
Ritsu hungers to see Mob’s eyes spark sharp with passion again, to be the one
who pierces through—who uncovers who Mob really is.
But every time, without fail, Mob just plasters on that small, placating smile
of his, utters some bland, meaningless reassurances. The milquetoast façade
he’s constructed to cage in his turbulent, lethal side frustrates—no,
angersRitsu, and some part of him wants badly to mar it, wants to wreck that
veneer of purity just a little bit.
He pads soundlessly over to the unmade bed and pauses, the barest moment of
hesitation before he sinks to his knees on the futon, the comforter depressing
graciously under his weight, a puff of Mob’s scent rising around him. Ritsu
breathes in deep.
In a way, he wants Mob to succeed in his goals. It’s probably good for him to
socialize with people other than that creepy adult ‘master’ of his, anyway. And
he does want Mob to be comfortable, and happy. Then again, happiness for Mob
apparently means being with Tsubomi, that exceedingly ordinary girl who always
used to take him away from Ritsu at the playground.
Ritsu feels a pinch of annoyance when he thinks of the way Mob’s puppy-dog eyes
follow her in the hallways at school. That Mob might become close to someone
like that—a total stranger, basically—and share his deepest secrets and desires
with her… Exactly what right does she have to his brother’s affections?
The thought of Mob doing anything with that girl—even just holding hands, or
talking with their heads close together, all intimate, makes something ugly and
selfish unfurl in Ritsu. As it is, Mob would do almost anything for him… and
Ritsu doesn’t plan on relinquishing that solitary privilege anytime soon.
Ritsu trails the tips of his fingers across the front of his neck, unbuttoning
the collar of his uniform. He feels warm, but it’s not from the weather, it’s
something else… something he’s associated with Mob from the very beginning. He
closes his eyes and slides his hand slowly down his torso, deftly undoing each
jacket button before he drops his palm between his legs, grinding it against
the slight bulge in his trousers.
Ritsu may only be in his first year of middle school, but he’s been doing this
for a while now.
The first time had been a couple summers ago, when he and Mob had been out of
school, home alone and wrestling on the couch for the remote. They had been
laughing and huffing and squirming, and at one point Mob managed to get on top
of him, one knee planted between Ritsu’s thighs. All it took was one tiny
shift, and suddenly Mob’s leg was pressing into his budding erection. Ritsu
gasped at the sensation, a surprised little half-moan escaping him. Mob’s eyes
flew wide at the sound, and he clambered immediately off of him, asking Ritsu
anxiously if he had hurt him.
Ritsu had licked his lips, breathing hard, wanting to say no, it doesn’t
hurt,andplease come back. But even then, he knew, somehow intrinsically, that
whatever he had just felt, he wasn’t supposed to. And while Mob clearly hadn’t
noticed anything out of the ordinary, Ritsu was afraid that if he did, he might
shun him—might never speak to him again.
Swallowing, Ritsu squeezes his eyes shut, and warily undoes the zip of his
pants. If only Mob knew that his little brother, for all his good grades and
social standing, had been masturbating to thoughts of him ever since he learned
how... Ritsu curses quietly, disgusted with himself, even as he wraps his
fingers around his growing hard-on and begins to stroke. The bed is forgiving
under his legs. He thinks of his brother’s eternally mild disposition, and his
thoughts turn dark.
No girl should have the power to make his Nii-san’s heart race, his cheeks turn
pink, to make him gasp and sigh. If anyone was going to get Mob to react, it
was going to be Ritsu.
He slips his free hand below his undershirt, brushing his fingers against his
skin lightly, and visualizes Mob’s timid mouth, his soft pale lips—thinks of
how they would feel peppering feather-light kisses down his chest, his stomach.
Ritsu’s thighs spread wider apart, his cock stiffening in his palm. He feels a
thin sheen of moisture break out on his forehead as he imagines Mob looking up
from between his legs, rubbing his cheek against Ritsu’s thigh before licking
lightly at the tip of his cock; dragging his hot, slick tongue all the way down
to the root, to kiss and suckle at Ritsu’s balls.
Ritsu squeezes himself and groans, feeling pre-come starting to leak at his
slit, and he reaches down with his other hand to spread it around, closing his
fist in a tight little cave of warmth around the head. He imagines the smooth,
wet heat of Mob’s mouth engulfing him—his lips would be so swollen, stretched
wide full of cock—and Ritsu lets out a quiet moan as his hips start to cant up
into his fist, greedy.
And it’s not like Mob would have any earthly idea what he was doing. Ritsu
envisions his brother struggling to breathe through his nose, his eyes red-
rimmed and watering, but still doing his best to make it good for him, clumsily
trying to bob his head into some semblance of a rhythm, and god—the thought of
a sweet, inexperienced Mob, who would do anything to please him—even let Ritsu
fuck his Nii-san’s pretty face—
“Hahh…”
Ritsu takes gasping breaths as he imagines yanking Mob off of him by his shiny
black hair—but he’s not quick enough, and thick white fluid runs down his
brother’s lips, paints his cheek in a messy wet streak. Mob coughs, his face
red, a hand moving to rub gingerly at his throat, sore from Ritsu forcing past
his gag reflex. He licks his bruised lips a little, tasting.
You spilled,the Mob in the mind says in this soft, raspy voice. He wipes the
substance from his mouth and cheek, inspects the way it glistens between his
fingers before holding his hand out to Ritsu.
In the scene playing out in his mind, Ritsu looks from Mob’s expressionless
face to his extended hand, and leans in. He would do it, too—lick and suck the
dripping fingers into his mouth, use his tongue to clean his own come off Mob’s
hand, like the trash he knows he is. Ritsu brings his hand up and slides his
fingers into his mouth, pushing them into his throat, choking a little—pretends
they’re his brother’s.
Ritsu tries to imagine what it would be like if Mob wanted him back—or more. If
he were so consumed by his longing for Ritsu, he would do whatever it took to
have him. A Mob that would use his powers to make Ritsu kneel for him, to take
control of his body so that he couldn’t get away, could only whimper and
shudder when his older brother’s fingers rubbed teasingly around his hole. So
stoic, so strong with his abilities that Ritsu could do nothing but beg,
desperate, as Mob slammed ruthlessly into him, over and over and over.
Ritsu shivers at the mental image and pulls his spit-covered fingers out of his
mouth, fumbling to shove his pants further down his thighs before pressing his
wet digits shakily against his entrance. He takes a stuttering breath, attempts
to relax as he pushes one carefully in.
Of course he wants this, he thinks. Under all that meaningless praise, this is
who he really is. Ritsu works his finger slowly in and out of himself, wincing
at the initial discomfort, but his breathing becomes heavier as the pain starts
to mingle with his arousal. After a few tries he finally hits his prostate, and
a full-body tremor rolls through him, his desire flaming hot under his skin.
“Nii-san,” Ritsu gasps softly. The stretch burns when he adds another finger.
The Mob in his mind’s eye doesn't speak, just thrusts into him hard from
behind, rough, possessive—perfect. Even in the fantasy, Ritsu only struggles
for show. The truth is he's always wanted this; as soon as he found out two men
could do this, this is what he's wanted from his brother. He rubs his fingers
against that spot again and jolts, fails to bite back a needy moan.
Maybe Mob would eventually tire of pinning him down and instead sit back, the
force of his powers enabling him to tug Ritsu back with him, to pull him into
his lap so easily, like a ragdoll. Maybe he manhandles him so that Ritsu’s
straddling his thighs, back flush against Mob’s chest, powerful hands crushing
his hips, guiding him, until he’s fucking himself on his brother’s cock.
And Ritsu would move, so obediently, his brother’s name a choked whisper on his
lips, taking him as deep as he could—deeper, until it hurt. In the fantasy,
Ritsu raises his arms, hands tangling in his brother’s hair behind him, whining
as Mob mouths at the side of his neck, teeth scraping lightly against Ritsu’s
pulse point. Mob’s fingers are everywhere, running down Ritsu’s sides, pinching
his sensitive nipples, slithering down to knead his trembling thighs as Ritsu
continues to ride him, unassisted, wanton. And Ritsu is bringing his hips down
as hard as he can, considering his shaky legs, sweat squelching at the backs of
his knees, but it’s still just not enough.
“Nii-san—”
His voice is wrecked, high-pitched and shameful, and Ritsu bites his lip in
embarrassment—but that doesn’t stop him from envisioning his brother rocking
into him, in short, rhythmic thrusts. He times the brush of his knuckles
against his prostate to the cadence of fantasy Mob’s grinding, and pictures Mob
reaching around to grasp roughly at Ritsu’s cock, bouncing thick and heavy
against his stomach, pre-come leaking sloppily down his pelvis. Ritsu uses his
non-dominant hand to grip his aching cock, giving it an unsteady stroke, and it
feels foreign enough that it’s almost like it’s really Mob touching him.
Heat shoots through his core, and it’s so much, the image of Mob rutting into
him, the vigor of his thrusts causing Ritsu’s cock to slide wetly in his
brother’s fist. Ritsu’s back is arching, muscles going tight as his hips piston
erratically into his own closed hand, and he feels himself clench around his
fingers as he jabs them a final time against his prostate, and that’s it—he’s
coming with a choked cry, almost a sob. His vision whites out and his cock
pulses, ejaculate shooting forcefully out of him.
Minutes later, Ritsu’s limbs are still tingling, his heartbeat still staccato
as he struggles to catch his breath. His heart stops when he hears the beep of
the alarm from the front door opening, and his eyes widen as he realizes he’s a
sticky, panting, half-dressed mess, sprawled out on a now soiled bed that is
very much not his own.
Ritsu sits up lightning fast, seeing stars as he hurries to yank his pants back
up, buttoning them in record time. His hands fly guiltily, frenziedly away from
his waistband when he hears the bedroom door open behind him.
“Oh - Ritsu,” Mob says softly, sounding the tiniest bit surprised.
Sweat dripping down the sides of his face, Ritsu turns to see Mob in the
doorway. “Nii-san,” he greets him, a breathless edge clinging to his voice.
“What are you doing in here?”
Before Ritsu’s brain even has time to catch up with his mouth, he’s already
tossing back casually, “Oh, sorry – it’s really hot in my room. The sun rises
on that side, so it shines directly into my windows all day.” He’s alarmed by
how easily the lie rolls off his tongue. But then he remembers how President
Kamuro enlightened him to his true nature, and his confidence in the fib grows.
He shrugs, the picture of nonchalance. “It’s so much cooler in your room, so I
came in here. I’m sorry if that wasn’t okay.”
Mob makes a small sound of understanding, completely accepting of the
explanation Ritsu just pulled out of thin air. But his eyes wander to Ritsu’s
open jacket, his rumpled clothes, and a concerned expression descends on his
features. “Are you okay? You still look kind of flushed.”
Ritsu feels blood rush to his face, but Mob doesn’t appear to notice. “It is
very hot outside,” he continues in his usual monotone. “You have to be careful
of dehydration and heat exhaustion. That’s what President Musashi from my club
said.”
Ritsu licks his lips nervously. He almost can’t believe Mob is buying this.
“Mm, yeah. I’ll feel better once I change out of this uniform,” he responds,
and smiles in what he hopes is a reassuring way. As he moves to get up, his
eyes land on a splash of his seed drying on the comforter. Panic grips briefly
at Ritsu’s skin once more and his mind races, thinking fast. “Actually, I’m
going to wash this for you, Nii-san. I spilled some juice on it earlier,” he
says, stepping off the bed.
“Oh? Let me see, it’s probably fine,” Mob says, coming closer to peer at the
blanket Ritsu is gathering in his arms.
“No!” Ritsu’s heart beats wildly as he jerks away from his brother slightly. “I
mean—I was going to wash some other things anyway, so it’s no trouble.” He
struggles to act naturally. His face is burning, and he’s almost dizzy at the
threat of being found out.
“Ah, I see. Thanks.”
Mob is looking at him strangely, and Ritsu averts his eyes. He hurries to step
around him towards the door, not wanting to push his luck, or give Mob any more
time to connect the dots, when—
“Ritsu.”
Dread fills his stomach. He turns his head to look back at Mob. “Y-yes?”
Mob is silent for a moment before he speaks. “Don’t tire yourself out if you’re
not feeling well. If there’s anything you need, or anything you want, just ask
me.”
Anything he wants? Ritsu thinks derisively, that inescapable strain of jealousy
flooding through him.
I want you to open up to me. I want you to show your true self to me. I want
your powers, so I can make you do terrible things to me.
Shame and desire and envy twist inside of Ritsu, coursing through his
bloodstream, seeping out his every pore.
He smiles tightly at his brother.
“Of course. Nii-san.”
                                     -fin-
End Notes
     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!