
Posted originally on the Archive_of_Our_Own at https://archiveofourown.org/
works/10554668.
  Rating:
      Explicit
  Archive Warning:
      Underage
  Category:
      M/M
  Fandom:
      モブサイコ100_|_Mob_Psycho_100
  Relationship:
      Kageyama_"Mob"_Shigeo/Serizawa_Katsuya, Kageyama_"Mob"_Shigeo/Reigen
      Arataka
  Character:
      Kageyama_"Mob"_Shigeo, Serizawa_Katsuya, Reigen_Arataka
  Additional Tags:
      Mentions_of_past_Serizawa/Shou, Unhealthy_Relationships_and_Dependency,
      past_emotional_abuse, Blow_Jobs, Facials, Voyeurism, Masturbation, starts
      out_sweet_and_gets_worse_over_time, Serizawa_is_a_broken_man
  Stats:
      Published: 2017-04-06 Words: 3831
****** How to Love a Boy ******
by Gwappo, Motte_(Gwappo)
Summary
     It takes much for Serizawa to feel comfortable in any situation, but
     luckily Mob is a helpful kid.
Notes
     This one goes out to Nico, whose belief in SeriMob inspired me to try
     and convert y'all to this severely underrated ship.
     Hope you guys enjoy!
See the end of the work for more notes
The first time Serizawa enters Reigen's office he flashes back to the day he
left his room: he's anxious and shaking, catching glimpses of a world so
foreign it teeters on the brink of unreal.
Back then he was determined to change its course, committed himself to the man
who wished to become its new center. If necassary, Touichirou once told him,
they'd keep the earth from turning to create a better tomorrow.
Today Serizawa knows those words were lies. The memories of his actions sting
sometimes when he lets them surface, but he's found another voice to lend him
strength.
"Bad experiences help us grow as people," Reigen says as he hangs up his suit
coat, rolls up his sleeves. "Think of it as a bee sting, for example. The pain
will fade after a few days, but the knowledge you gained will remain right
here," he taps a finger against his temple, sits down in his chair. "You know
you won't swat at bees with your bare hands again. Now, take a seat, please."
Serizawa doesn't quite get the metaphor, but the prospect of seeing the boy who
saved him again makes him hold his chin higher.

===============================================================================

When Mob comes in for work that day, Serizawa waits until they're alone in the
room to thank him.
"For everything," he says, running a twitchy hand through his newly cut hair.
"I was your enemy when we first met, but you still decided to help me. You and
your master have been nothing but kind to me ever since I met you. I'm very
thankful for that."
Mob blinks up at him. He's so flat now, not at all like the boy he remembers
shouting and screaming that day, all fiery eyes and clenched teeth. "You're
welcome, but you don't need to thank me. I did what I thought was right."
Serizawa smiles nervously, wringing his hands, and Mob's voice finally pitches
upwards as he says, "I'm sure you'll do great. It's nice having you with us."
He sits down at the coffee table and rummages through his backpack as Serizawa
refills Reigen's coffee mug, worrying his bottom lip all the while.

===============================================================================

Reigen takes them out on a job the next day. He explains the benefits of
walking over driving as they make their way downtown to an old warehouse,
abandoned for a year, possibly haunted. Serizawa doesn't understand a lot of
Reigen's arguments, but Mob listens closely to his every word, so he does the
same.
The warehouse, it turns out, is filled to the brim with garbage. Reigen heaves
a sigh as they survey the scene, then makes a fast, complicated gesture with
his hands. "We'll split up, take a look around. The ghost will probably turn
out to be giant rats. Tell me if you sense something."
And he's off into the maze of old furniture and household appliances, Mob
heading in the opposite direction.
Something creeps up Serizawa's back as they disappear from sight, a sense of
forlornness he thought he left at his mother's house the day he woved to never
return to his room. He's not used to being left to his own devices when it
comes to work; Touichirou always had a vision, no matter how small the task.
Reigen, Serizawa realizes as his heartrate picks up, might be stitched from a
different material.
His hands shake as Serizawa lifts them to grab onto his forearms, holds himself
steady as his lungs suddenly heat up and every breath leaves a mild sting
somewhere behind his ribs, fingernails digging into the fabric of his suit, and
he really wishes he still had his umbrella right now, something to help protect
himself from the rising nausea.
"Serizawa," he hears from nearby, a voice so calm it raises goosebumps on the
back of his neck. He whips his head around, legs twitching to make a run for it
as Mob watches him from around a corner. "You can come with me if you don't
know where to look. Master Reigen can be a bit unspecific at times."
He waits patiently as Serizawa swallows the lump in his throat, slowly releases
the grip on his arms. His heart still racing and his breathing still ragged he
takes a few steps towards Mob, who turns around and watches over his shoulder
for him to follow.
"There are two paths here," the boy explains. "We can split up to save time."
"Where do you want me to look?" Serizawa's voice breaks on the last syllable,
but he manages to supress a flinch.
Mob turns his head to the left, to the right, and back to Serizawa. "You can
take the right," he says, "and I'll be over here. You can tell me if you find
anything, and then we can let Master Reigen now."
The tone of voice doesn't quite fit, but the familiarity of being given orders
pushes Serizawa back into his comfort zone, lets him breathe again. He gives a
slight nod, shakes out his hands, and Mob rewards him with a friendly smile.
Something inside of him unfurls itself as Serizawa heads to the right, pushing
aside memories of tall men with dashing smiles and bright blue eyes.

===============================================================================

Mob holds out his hand one time, picks Serizawa up from the ground after he
tripped; the feeling of warm skin and careful, soft fingers wrapping around his
own haunts Serizawa for days, keeps him up at night as he touches himself.

===============================================================================

Reigen rarely passes out direct orders. He spends a lot of time at his desk
taking all kinds of notes, sometimes in neatly kept notebooks, sometimes on
napkins. He sits with his feet up on the desktop a lot whenever he thinks
nobody's watching.
Serizawa spends a lot of his time cleaning. He prefers to keep his hands
occupied, so he doesn't mind, but Reigen's office is on the small side and kept
in surprisingly neat condition already.
The soles of his feet start brimming on days when they don't to much, a
reminder that work should be spent working. His eyes keep twitching in Mob's
direction, occupying himself with homework at the coffee table, but every time
Serizawa contemplates sitting down with him his feet refuse to move.
Reigen eventually excuses himself for 'business related stuff, I'll be back in
half an hour,' and the door falling shut rings through Serizawa's head like a
gunshot.
"Ah. Master is going to smoke."
Mob lets loose a tiny sigh, then focuses back on his schoolwork. Seconds tick
by loudly on the wall clock, paired with the light scratching sound of Mob's
pen, and finally Serizawa wills his body to approach the boy, even as his knees
wobble with every step.
He sits down on the opposite end of the sofa, wipes his damp palms on his
slacks. He can feel Mob's gaze on the side of his face and takes a deep breath
before he turns to meet it. The wall clock ticks, ticks, ticks before Mob asks,
"Are you okay, Serizawa? You're sweating."
He doesn't remember the last time he felt okay after leaving Touichirou; maybe
he didn't feel okay even then. Mob leans back in his seat as Serizawa breaks
eye contact, shifts his view towards the kid's hand resting limply beside his
thigh now. He slides his own hand across the space left between them, grabs
onto Mob's with shaky fingers, gives it a light squeeze.
It's just as comforting as he remembered, just as warm and soft as he recalled
it being many a night spent awake in his too large bed, too quiet flat. Those
short, slender fingers twitch lightly for a fracture of a second, but they
never draw away.
"Tell me if I'm overstepping any boundaries," Serizawa says, remembering the
times he got too friendly with Touichirou. They're so unalike yet similar in
every way, and for a second Serizawa almost hopes for Mob to blast him back
with a burst of his powers.
Instead he squeezes back with vigor, and when Serizawa chances a quick glimpse
at his face, he's smiling. "You're my friend," Mob says, "So this is okay. I
hold hands with my brother sometimes."
Serizawa wonders whether said brother's hands feel just as soft as he strokes
Mob's with his thumb, revels in the fact that he's allowed to do so. But the
boy tugs on his arm lightly, says, "You can come closer if you want," and
Serizawa's eyes shoot open wide.
He knows that phrase. It sends a lukewarm shiver through his body that settles
somewhere between his ribs and abdomen, and when Serizawa lifts his eyes he
almost expects to see the red-haired boy with the piercing blue eyes sitting
there instead, smirking with his hand too close to his own crotch, telling him
about how father won't be home for the day, about the offer of a wet tongue and
a young, slender body.
But the hand he's holding onto still belongs to Mob, with his black hair and
deep brown eyes, his lithe torso, lither limbs. It's too tempting a prospect,
and Serizawa slides closer to him without a second thought to consequences.
They're thigh to thigh, entwined hands resting on their legs. Mob leans back a
fracture of an inch to look up at Serizawa, searches his eyes for something.
His mouth is slightly open, pale pink lips parted to reveal a hint of white
teeth. He blinks, eyes slightly lidded, showing off surprisingly long lashes
for such a young boy.
Serizawa brings his other hand up slowly to hold Mob's face, cups his smooth
cheek, and the gentle warmth spreading through his palm stops his fingers from
trembling. For the first time since taking this job, Serizawa feels at peace.
But Mob shies away from the touch, shifts his head to the side to put space
between them, eyebrows twitching quizically underneath his bangs. "What are you
doing, Serizawa?" he asks, voice soft and confused.
They're still holding hands, so Serizawa gives him a squeeze.
He's familiar with games like this, too – playing 'hard to get' was what Shou
liked to call it, one hand down Serizawa's pants, the other holding his mouth
shut as he talked about all the things his father might do were he to know his
lackey had touched the boy without permission.
So Serizawa says, "I'm getting closer," as he gently strokes Mob's cheek with
his knuckles, brushes away a few strands of hair with his fingertips .
Mob keeps his eyes fixed on Serizawa's face as he leans into the touch ever so
slightly, lets one finger trace the line of his jaw and another the curve of
his lips.
His thumb and index finger are steady as Serizawa holds Mob's chin in them and
pulls the kid in for a first, tentative kiss.
It's light and sweet, almost chaste in a way Serizawa hasn't experienced
before. The urge to spread Mob's mouth wide open dwindles as the boy pulls away
after a few short seconds, squeezes the hand that's so much bigger than his
own. He leans their foreheads together, noses touching, mouths not quite in
reach of each other.
It's entirely new but nice, and Serizawa feels content to indulge him for a
moment longer.
A metallic click finally makes him jolt, sends a panic through Serizawa's body
that wraps itself around his chest, constricting every quick breath he takes as
their heads whip around in unison.
Reigen is standing at the door, hands in his pockets. He looks too casual, too
calm, and Serizawa braces himself for a fight, for a painful lesson in decency
about when and where and how to touch what doesn't belong to him.
But Reigen lazily nods his head at the windows. "You left the blinds open," he
says, and strolls over to shut the first one. "This is a ground floor office. A
random passerby could have seen you guys and called the police." He shuts the
second set of blinds, and the room instantly becomes a lot dimmer.
Serizawa feels frozen in place, one hand still holding Mob's, the other
hovering beside the boy's face – he quickly draws it back, clenches it in his
suit jacket. Reigen rolls his office chair around the desk – he locks the door
with a loud, harsh click on the way – and places it across from the coffee
table and sofa.
When he takes a seat, Serizawa starts shaking again. "I–I'm sorry," he tries,
feeling so small all of a sudden. "I, th–this is not what it looks like, I
promise. I would never – I'd never, I –"
Reigen clears his throat, crosses one leg over his knee as he leans back in his
chair. "I don't know what you're apologizing for," he says, "but I think you
guys were in the middle of something. Please," he extends a hand towards them,
"feel free to finish. It'd be rude of me to interrupt."
The rest of Serizawa's explanation dies somewhere between his vocal cords and
windpipe ("I'd never touch what's yours without your explicit permission") as
he recognizes this as Reigen's way of passing out orders – indirect and
unspecific, yet leaving no room for argument.
This time, Mob is the one to reach out first, careful fingers turning them face
to face by Serizawa's jaw, mouth on his own before he can try and read the
boy's reaction.
They're less careful now, Mob holding them pressed together, but still moving
his mouth too gently for it to feel right. It's never been this way, never been
tender and slow, and it puts Serizawa on edge to feel so lost in a situation
he's so used to.
Mob gasps as his lips are forced open, reflexively bites down on the tongue
being shoved in his mouth and the pain surges through Serizawa's body, makes
him shudder as he grabs Mob by the hips and pulls him closer, letting go of his
hand for the first time in what feels like forever.
The kid can't quite match his pace, his movements, but Serizawa delights in the
way he gives it his all, how small his mouth feels fitted against his own, how
tiny his waist seems under broad hands; he supresses the urge to knead the soft
form into a bruised mess, doesn't crush it even when his hands twitch to do so.
Mob slings both his arms around Serizawa's neck, lifts himself off of the sofa
to try and match their height, hands scrambling across his back, trying and
failing to find purchase in the smooth material of his suit.
They're both still dressed, still decent, so Serizawa brings his hands up to
Mob's uniform jacket and pop, pop, pops the buttons without hesitation (Shou's
jacket had buttons just like these), runs his palms up Mob's chest to his
shoulders and pushes him back down to slide it off, never letting go of that
thin, narrow mouth.
But Mob still has a shirt on, smooth cotton that Serizawa fists his hands into,
and he has to break the kiss to lift it over his head, toss it aside blindly.
He takes a moment to take in what he has exposed: Mob is smooth in every way,
from his shoulders to his hips and tummy, no marks on his skin, no stories
there to tell.
Serizawa grabs his head with both hands, crushes their mouths back together,
but Mob shoves at his chest and immediately slides his hands underneath the
suit jacket as Serizawa lets go of him. They work it off together, and Mob's
fingers shoot down to the buttons on the white dress shirt, bypass the tie, and
Serizawa's cock gives a violent twitch in his pants.
Mob untucks the shirt with nimble fingers, puts his open palms on Serizawa's
stomach who swallows down a sudden bolt of insecurity about the hairy, flabby
mess he must appear compared to Mob's flawless skin. He turns his head to the
side to avoid any judgmental looks as they work his shirt off, and from the
corner of his eyes he catches a glimpse of Reigen stroking himself through his
pants with one hand, the other holding his chin in a thoughtful position, elbow
on the armrest of his chair. But Serizawa is familiar with taunts and insults,
and he runs his hands down Mob's arms to his wrists, holds them both in one
hand and goes back in for another kiss.
They're getting sloppier, less technique and more raw need as Mob carefully
digs his teeth into Serizawa's bottom lip, pulls on it lightly, and he can't
keep the sounds in anymore as he kisses the boy even harder, deeper, and his
moans vibrate through both their bodies. Mob is trembling beneath his hands,
goosebumps on his skin as one palm slides up his ribcage, careful to catch
every ridge on its way upwards.
Mob tries to tug his hands free but Serizawa's hold doesn't give, doesn't
budge, as he slides his palm back down again, opens the boy's leather belt with
trained ease. He puts his hand on Mob's thigh for now, draws his head back to
give them both a moment to process the situation.
"Mob," they turn their heads in Reigen's direction. "Why don't you get down on
your knees for Serizawa?"
Reigen's voice is slightly strained now, one hand working his cock through the
open button fly of his slacks, the other hand still holding his chin in a
thoughtful pose.
Serizawa is still distracted when Mob frees his wrists and drops to his knees
eagerly, spreads Serizawa's legs apart and wedges himself in between them. He
looks up, and their eyes meet as his hands work belt and buttons free, fingers
trembling with either nerves or anticipation. He looks so short down on the
floor like this, but one hand boldly slides into Serizawa's boxers, and he
helps the kid by tugging down his pants to give him better access.
Mob takes a moment to look at the cock in his hand, traces his thumb up a vein
before he gives the head a small stroke and the shaft a few pumps. Serizawa
squeezes his eyes shut and takes a few shuddering breaths (it's too tender, too
tender, this kid is going to kill him) but he gasps when Mob's mouth suddenly
engulfs him, and so does Reigen from across the room.
Mob can't fit much in his mouth – he barely gets past the head before he starts
choking – but the way his tongue moves, the precision with which he finds the
right spots to caress with his tongue and hand tells Serizawa he's done this
before. Reigen draws a hissing breath when Mob brings up his other hand to
stroke Serizawa's balls with, and he knows exactly who taught the kid.
He finally opens his eyes once he grows accustomed to the sensations, watches
Mob work diligently, head bobbing lightly in his lap, hair compelling him to
run a careful hand through it with the way it sways.
Serizawa knows he's close but he's learned to restrain himself, has learned to
fuck and cum on command, and he wants to enjoy a sight he's never been allowed
to just watch before. He runs his hand down to the back of Mob's head – not
forcing, merely guiding – keeping his touch light as that tongue swirls around
his head again, licks up salty precum, and the tiniest sound escapes the boy's
throat, vibrates through Serizawa's body to make him choke out a moan, and when
Mob suddenly opens his eyes and looks up at him, swallows down as much as he
can fit, it finally becomes too much to bear.
Serizawa digs his other hand into his own thigh, tries to numb the ecstasy with
the pain of short, blunt nails biting into flesh, but it drives his high even
higher, and he's coming in Mob's mouth with a groan and a snap of his hips.
But Mob draws his head back in shock, coughs as cum runs down his chin and
Serizawa coats his nose, his cheeks, his hair, leaves his pretty young face a
mess.
Reigen is panting somewhere in the background, chair creaking with the strain
of his movements, but Serizawa keeps his gaze on Mob, on those big eyes looking
down at the hand he used to wipe excess cum from his chin with. He lifts his
face a moment later and keeps eye contact with Serizawa as he brings the hand
up, pops a stained finger in his mouth with a wet plop, and in that moment the
world really must have stopped turning in the face of a sight so extraordinary.
"You're beautiful," he tells the boy, voice amazed but steady, and a shaking
moan tells him that Reigen cums at the words.
Serizawa pets Mob's hair, falls in love with the way he rubs his face into that
broad hand, the way his chest expands in a long, contented breath. The kid
draws his hand back from Serizawa's body, lets go of his soft dick without
tucking him back in.
"Mob," and they turn their heads again, slower this time. "Mob, get up on
Serizawa's lap, or come over here," Reigen says, sitting slumped in his chair,
hands stapled in front of his face, pants already buttoned up again. He would
look calm and collected if it weren't for the sweat on his brow and the cum on
his shirt and jacket.
But Mob's face grows hot under Serizawa's hand, and he shifts around
uncomfortably. "It's alright, Master," he whispers, "I'm already done."
Reigen closes his eyes and inhales deeply, then gulps and nods his head.
"Alright," he says, "Alright. Get dressed, you two. It's after closing hours, I
don't want you doing overtime."
And Mob disengages himself from Serizawa's hand as he gets up to gather his
clothes, and Serizawa misses his warmth as soon as it's gone, looks down at his
palm wondering if he will get to feel it again.
They dress themselves quietly, but when Mob passes by him on his way out he
shoots Serizawa a tiny smile, wipes a paper towel across Serizawa's sweaty
forehead in a gesture so sweet it nearly makes his eyes water.
It's the same old, same old, and yet it's so new and different that Serizawa
leaves the office with his head spinning, mind unable to connect what's
familiar to the new and foreign experiences he made today, unsure which
outweigh which.

===============================================================================

Serizawa doesn't sleep that night, recalling the sound of Mob's voice and the
way his body moved with so much young grace, unlike the erratic, needy
undulances he was so used to for so long.
Maybe, he thinks as he traces patterns on the ceiling with his eyes, this is
what Touichirou was aiming for when he told him he'd 'teach him how to love a
boy'.
End Notes
     Please feel free to point out any mistakes, English isn't my first
     language and I'd love to improve!
     Also feel free to drop by my twitter @hentaijohnson anytime!
Please drop_by_the_archive_and_comment to let the author know if you enjoyed
their work!
