Debt Of Memory
Pairing: Mafia Boss!Lee Heeseung × Fem!Reader
Genre: mafia au, billionaire au, childhood lovers, amnesia, angst, romance, possessive heeseung, fluff, action, enemies to lovers kinda, hurt/comfort
Synopsis: After your family falls into crushing debt, ruthless mafia boss Lee Heeseung gives you an impossible offer: work for him for six months in exchange for your family’s freedom. Cold, dangerous, and feared across Seoul, Heeseung treats everyone like they’re disposable — except you. As blurry memories begin haunting you, you slowly uncover the truth: the debt was fake, the mafia boss has been searching for you for years, and the boy you forgot never stopped loving you.
Word Count: 23k+
Before Everything Fell Apart
Years ago, before Seoul feared the name Lee Heeseung…
He was just a lonely boy.
A boy with bruised knuckles, tired eyes, and too much anger for someone so young.
His father was already involved in dangerous underground dealings back then. Even as a teenager, Heeseung lived surrounded by violence, threats, and bloodshed.
At school, rumors followed him everywhere.
Monster’s son.
Future criminal.
Dangerous.
No one wanted to sit beside him.
No one except you.
───
You were sixteen when you first spoke to him properly.
Rain poured outside the school building while Heeseung sat alone on the rooftop edge.
One wrong movement and he would fall.
He didn’t look scared.
That was the terrifying part.
His eyes were empty.
Completely empty.
You walked toward him carefully.
“Hey.”
No response.
“You know people usually use rooftops for dramatic crying scenes, right?”
Silence.
Then finally—
“Go away.”
You crossed your arms.
“No.”
Heeseung looked irritated.
“I’m serious.”
“So am I.”
You slowly sat beside him despite the dangerous height.
The city lights reflected in his dark eyes.
“You shouldn’t sit there,” he muttered.
“You shouldn’t either.”
His jaw tightened.
“Why do you care?”
You shrugged lightly.
“Because you look lonely.”
Something flickered across his face then.
Pain.
Real pain.
You spoke softly after a moment.
“My grandmother says people who want to disappear usually don’t actually want to die.”
Heeseung stared ahead silently.
“They just want the pain to stop.”
The rooftop became quiet except for rain.
Then suddenly—
Heeseung laughed.
A tiny, broken laugh like he had forgotten how.
“You talk too much.”
“And you think too much.”
For the first time in years…
Someone treated him like a normal person.
Not a monster.
Not a threat.
Just Heeseung.
And from that day onward—
You became the center of his world.
───
The Girl He Never Forgot
You and Heeseung became inseparable.
He walked you home every day.
You forced him to eat when he skipped meals.
He silently waited outside your part-time job just to make sure you got home safely.
No confessions were needed.
Everyone already knew.
You belonged to each other.
Even back then, Heeseung was possessive.
Violently protective.
One afternoon, a group of boys cornered you behind the school building.
Before you could react—
Heeseung appeared.
And something terrifying happened.
The quiet boy everyone mocked suddenly snapped.
His fists became bloody within minutes.
He beat them so brutally the principal almost called the police.
You had grabbed his trembling hands afterward.
“Heeseung, stop.”
His breathing was uneven.
“They touched you.”
“They’re already hurt.”
“They deserved worse.”
You should’ve been scared.
But instead—
You gently wiped blood from his cheek.
And Heeseung looked at you like you were the only thing keeping him human.
───
Then the accident happened.
The night that destroyed everything.
───
Heeseung still remembers it perfectly.
Every detail.
The rain.
Your laughter in the passenger seat.
The way your hand rested in his.
Then—
Bright headlights.
Screeching tires.
Your scream.
And blood.
So much blood.
───
When Heeseung woke up in the hospital, the first thing he asked was your name.
But your parents looked devastated.
“She doesn’t remember anything.”
The doctors called it trauma-induced memory loss.
You forgot your school.
Your friends.
Your childhood.
Him.
Everything.
And before Heeseung could even see you—
Your family moved away to Busan for treatment.
Then later overseas.
Gone.
Just like that.
For years, Heeseung searched for you.
But you disappeared completely.
And the boy you once saved slowly became the monster.
Ten years later.
Lee Heeseung ruled Seoul from the shadows.
The mafia world feared him.
Businessmen bowed before him.
Enemies vanished overnight.
And Heeseung himself became colder than winter.
Emotion no longer existed in his world.
Only power.
Violence.
Control.
───
The abandoned warehouse smelled like blood and gasoline.
A traitor knelt in front of Heeseung trembling violently.
“Please… please give me another chance—”
Heeseung sat silently on the chair before him.
Black gloves.
Black suit.
Emotionless eyes.
Jay stood nearby holding files while Sunghoon kept a gun pointed at the man’s head.
“He sold information to the Daehan group,” Jay explained calmly.
The traitor sobbed harder.
“I needed money—”
Heeseung tilted his head slightly.
“And?”
The man froze.
That single word carried terrifying weight.
Heeseung stood slowly.
Every person in the warehouse immediately lowered their heads.
Even breathing felt dangerous around him.
“You betrayed me for money,” Heeseung said quietly.
Then suddenly—
CRACK.
The sound of Heeseung’s gun echoed through the warehouse.
The man collapsed instantly.
Dead.
No hesitation.
No mercy.
Heeseung handed the gun back to Sunghoon without expression.
“Clean this.”
“Yes, boss.”
Jay watched Heeseung carefully.
“You haven’t slept in three days.”
“I’m fine.”
“You killed four organizations this month.”
“They were careless.”
Jay sighed quietly.
Heeseung had become worse recently.
More violent.
More unstable.
Like he was searching for something he could never find.
Then Sunoo entered quickly.
“Boss.”
Heeseung looked up.
Sunoo placed photographs onto the table.
“We found her.”
The world stopped.
For the first time in years—
Emotion cracked through Heeseung’s cold expression.
The rain hit the windows of the Black Circle headquarters in steady, violent rhythm.
Heeseung stood at the center of the room, unreadable as always.
But today—something in him was different.
Tighter.
Sharper.
Like something long buried had finally resurfaced.
Sunoo placed the file on the table.
“She’s confirmed. Same identity. Same school records. It’s her.”
Silence followed.
Jay studied Heeseung carefully.
“…What do you want to do?”
Heeseung didn’t answer immediately.
His eyes stayed on the file.
On your face.
On the proof that you were finally here.
Alive.
After all these years.
Then, calmly—
“Bring her to me.”
Hours later.
You stood inside a cold, expensive room you didn’t belong in.
And in front of you was him.
Lee Heeseung.
The man everyone in Seoul feared.
He didn’t waste time.
“Your family is in debt.”
Your brows furrowed.
“That’s impossible. We—”
“It is,” he cut in flatly.
A pause.
Then he continued, voice colder.
“But I can erase it.”
Your heart tightened.
“What do you want in return?”
That was when he finally looked at you properly.
Not like a stranger.
Like something he had been searching for his entire life.
“You.”
Silence crashed between you both.
“…What?”
Heeseung stepped closer.
Not threatening.
Not loud.
Just certain.
“You will work for me. Six months.”
His voice lowered slightly.
“Stay at my estate. Follow my instructions. No questions.”
Your jaw tightened.
“And if I refuse?”
For the first time—
Something dangerous flickered in his expression.
“Then your family loses everything you’re trying to protect.”
A beat.
Then softer—but only slightly:
“You don’t have another choice.”
You hated how calm he sounded.
Like your life had already been decided.
Like he already knew you would say yes.
And somehow…
He was right.
You exhaled slowly.
“…Fine.”
The single word made something shift in the room.
Jay blinked slightly.
Even Sunghoon looked up.
But Heeseung—
He didn’t react at all.
Only nodded once.
“Good.”
Then, after a pause that felt heavier than it should—
“You will start working after a week."
───
You had finally returned to Seoul.
You didn’t even want to come back.
But after your father’s business collapsed, your family had no choice.
Everything felt strangely familiar though.
The streets.
The rain.
The city itself.
Like memories sat just beyond your reach.
And the headaches started almost immediately.
Small flashes.
A rooftop.
A boy smiling.
Warm hands holding yours.
But every time you tried remembering clearly—
Pain exploded through your head.
That night, Heeseung couldn’t breathe properly.
His office remained dark while rain hit the windows.
On the desk sat old photographs of you both as teenagers.
Pictures he kept all these years.
You smiling beside him.
Your head resting on his shoulder.
His fingers trembled slightly as he stared at them.
“She forgot me,” he whispered.
Jay stood quietly nearby.
“But she’s alive.”
Heeseung closed his eyes.
For years he believed he lost you forever.
And now you were suddenly back.
Breathing.
Existing.
Close enough to touch.
Yet looking at him like a stranger.
Something possessive and desperate awakened inside him again.
The dangerous kind.
“Keep people watching her.”
Jay sighed softly.
“Heeseung—”
“I said keep watching her.”
His voice turned cold instantly.
Nobody argued further.
───
Over the next weeks, Heeseung monitored everything.
When you skipped meals, food mysteriously appeared at your apartment.
When creepy men followed you after work, they disappeared permanently.
When your landlord threatened your family—
His entire building was suddenly bought overnight.
You had no idea Heeseung stood behind any of it.
But the headaches worsened.
Memories clawed harder every day.
Especially whenever you saw him on television.
His voice.
His eyes.
His presence.
Everything hurt your heart in ways you couldn’t explain.
───
Then one evening—
You fainted.
The moment Heeseung received the call, he abandoned a mafia negotiation midway.
A terrified subordinate tried stopping him.
“But boss, the Russians are waiting—”
“I don’t care.”
That single sentence shocked the entire organization.
Lee Heeseung never abandoned work.
Never.
Yet he drove through Seoul at dangerous speed just to reach you.
When he entered your apartment and saw you unconscious on the floor—
Something inside him shattered.
He carried you carefully to the couch.
Your face looked pale.
Fragile.
His thumb brushed gently against your cheek.
“Y/n…”
For the first time in years—
The ruthless mafia boss looked terrified.
───
You woke up slowly.
And immediately panicked seeing Heeseung beside you.
“What are you doing here?!”
“You collapsed.”
Your head still hurt horribly.
Fragments kept flashing rapidly now.
A rooftop.
Laughter.
Blood.
A promise.
Then suddenly—
You remembered his voice.
“You’re the only good thing in my life.”
Your breathing stopped.
You looked at Heeseung again.
Really looked at him.
And tears filled your eyes without warning.
“…Heeseung?”
The room became silent.
Completely silent.
Heeseung stared at you like the world itself had frozen.
Then finally—
Very slowly—
He nodded.
Your chest ached violently.
“You… you were…”
His expression softened painfully.
“Your boyfriend.”
The memories hit all at once.
The rooftop.
The accident.
His smile.
Your first kiss.
The way he used to hold your hand.
And suddenly—
You remembered loving him.
Years of forgotten feelings crashed into you at once.
You started crying.
Heeseung immediately moved closer.
“Hey.”
You grabbed his shirt desperately.
“I forgot you.”
His eyes darkened with emotion.
“I know.”
“I’m sorry—”
“Don’t apologize.”
His voice broke slightly.
And hearing that nearly destroyed you more than anything.
Because this terrifying man—
This ruthless monster feared by all of Seoul—
Had spent years loving someone who couldn’t even remember his name.
After your memories returned, everything became clearer.
The debt.
The obsession.
The protection.
Heeseung never targeted your family out of revenge.
He created the debt because he couldn’t approach you normally.
Not after becoming who he was.
Not after turning into someone covered in blood and violence.
So instead—
He forced you into his world.
Just to stay close.
And somehow that was even more heartbreaking.
───
One night you entered his private office quietly.
Heeseung stood by the window overlooking Seoul.
The city lights reflected against his cold expression.
“What are you thinking about?”
He answered honestly.
“How easy it would be to burn this city down for you.”
Your heart tightened.
Heeseung finally turned toward you.
“You remember what I used to be.”
“I do.”
“And you still stayed.”
You walked toward him slowly.
“Because I know who you are underneath all this.”
Something vulnerable crossed his face.
Rare.
Dangerous.
“You make me weak.”
You shook your head gently.
“No.”
You placed your hand over his heartbeat.
“You make yourself human around me.”
For a long moment, Heeseung said nothing.
Then finally—
He pulled you into his arms carefully.
Like he was afraid you’d disappear again.
And maybe that fear would never leave him.
Because Lee Heeseung could control Seoul.
Control violence.
Control fear.
But losing you?
That remained the one thing powerful enough to destroy him.
Living inside Heeseung’s world meant learning its rules quickly.
And surprisingly—
Your work for him had very little to do with violence.
At least directly.
Heeseung refused to let you near dangerous operations no matter how much you argued.
“You’re not going,” he said coldly one evening while adjusting his cufflinks.
You crossed your arms stubbornly.
“I literally work for you.”
“You organize schedules.”
“I can do more than paperwork.”
“No.”
His answer came instantly.
Firm.
Absolute.
It annoyed you endlessly.
───
Your actual responsibilities became strangely domestic compared to the terrifying world surrounding him.
You handled appointments for LHS Holdings.
Managed event schedules.
Organized meetings.
Reviewed documents before Jay brought them to Heeseung.
You even started helping Sunoo sort encrypted files and digital records because, according to him:
“You’re less scary to work with than Heeseung.”
At first, everyone expected Heeseung to lose patience with you quickly.
But instead—
The mafia boss of Seoul became impossibly attentive around you.
If meetings lasted too long, food appeared beside your workspace.
If you looked tired, Heeseung silently cancelled half your schedule.
One morning you casually mentioned your chair hurting your back.
The next day—
A custom luxury ergonomic chair appeared in your office.
You stared at it in disbelief.
“Absolutely not.”
Jake nearly laughed.
“Heeseung personally picked that out.”
Your jaw dropped.
“He spent two hours choosing a chair?!”
Sunoo grinned mischievously.
“He almost fired the salesman.”
───
The spoiling only became worse over time.
Designer clothes appeared in your closet.
Expensive skincare products filled your bathroom.
He replaced your broken phone with the newest model after hearing you complain once.
And every single time—
He acted completely normal about it.
One night you confronted him while he worked in his office.
“You can’t keep buying me things.”
Heeseung barely looked up from the documents.
“Why?”
“Because it’s ridiculous.”
“You needed a new phone.”
“I did not need one worth more than my rent.”
He finally looked at you then.
Completely serious.
“You deserve good things.”
Your chest tightened embarrassingly fast.
You looked away immediately.
“That’s unfair.”
“What is?”
“The way you say things.”
A faint smile appeared on his lips.
Rare.
Small.
Dangerously pretty.
“You still blush too easily.”
Your face became hotter instantly.
And Heeseung looked entirely too pleased about it.
───
Despite his terrifying reputation—
The quiet moments with Heeseung became your favorite.
Late nights in his office while rain hit the windows.
Sharing takeout because he forgot to eat again.
Listening to him speak softly about things nobody else knew.
He rarely opened up.
But with you—
He tried.
One evening, you found him sitting alone on the mansion balcony after returning from a mission.
Blood stained his knuckles.
His expression looked distant.
Tired.
You quietly sat beside him.
Neither of you spoke for a while.
Then softly—
“Did someone die tonight?”
Heeseung stayed silent.
That silence itself was answer enough.
Your heart ached.
“You hate it sometimes, don’t you?”
He leaned back slowly.
“This life?”
You nodded.
For once, the great Lee Heeseung looked exhausted instead of powerful.
“There are things I can’t undo anymore.”
The cold wind brushed through his dark hair.
“I built this organization with violence. Fear keeps people loyal.”
His voice lowered.
“If I become soft, people die.”
You looked at him carefully.
“But you’re soft with me.”
His eyes shifted toward you immediately.
“That’s different.”
“How?”
Heeseung stared at you for a long moment.
Then quietly admitted—
“Because you knew me before I became this person.”
The vulnerability in his voice nearly broke your heart.
You reached for his injured hand gently.
“Then let me know both versions of you.”
Something emotional flickered across his expression.
And slowly—
His fingers intertwined with yours.
───
The Most Feared Man In Seoul
The organization quickly realized one terrifying fact.
You could control Heeseung better than anyone else.
Including himself.
One afternoon, Heeseung completely lost his temper during a meeting.
A subordinate had leaked information to rival groups.
The room felt suffocating.
Everyone stood frozen while Heeseung slowly approached the terrified man.
“You betrayed me.”
His voice remained calm.
Which was worse.
Much worse.
The man dropped to his knees immediately.
“Boss please—”
Heeseung grabbed his collar violently.
“Do you think loyalty is optional?”
Nobody moved.
Nobody breathed.
Because everyone knew what happened next usually.
Blood.
Screaming.
Death.
Then suddenly—
You entered the room carrying coffee.
And froze.
“…Am I interrupting?”
The entire room went silent.
Jay looked horrified.
Jake looked nervous.
The subordinate looked seconds away from death.
Heeseung slowly turned toward you.
And instantly—
His expression softened.
Not completely.
But enough to shock everyone present.
You glanced at the trembling man.
Then quietly looked back at Heeseung.
“Maybe don’t kill him before lunch?”
Dead silence followed.
Sunoo physically covered his mouth to stop laughing.
Because only you would say something insane like that to Lee Heeseung.
And somehow—
He listened.
Heeseung exhaled slowly before shoving the man away.
“Get out.”
The subordinate nearly cried from relief while escaping.
The moment the doors closed, Jake whispered:
“She literally just saved his life.”
Sunghoon nodded once.
“Again.”
───
Heeseung’s version of affection was dangerous.
Possessive.
Silent.
Excessive.
But somehow deeply sincere.
───
You once mentioned liking strawberries casually during breakfast.
The next morning—
An entire luxury fruit arrangement arrived from Japan.
You stared at it in disbelief.
“Heeseung.”
He looked up from his coffee calmly.
“Yes?”
“This is insane.”
“You like strawberries.”
“That doesn’t mean I need imported ones!”
“They taste better.”
You blinked at him.
“You’re impossible.”
A faint smirk touched his lips.
Yet despite all the expensive gifts—
His softest gestures always mattered more.
The way he tucked blankets around you when you fell asleep in his office.
The way he automatically pulled you away from crowded streets.
The way he silently warmed your cold hands during winter drives.
Or how every night—
No matter how busy he was—
He checked whether you had eaten properly.
Always.
Without fail.
───
One evening, you entered his room quietly after a nightmare.
Heeseung immediately looked up from his laptop.
“What happened?”
You hesitated awkwardly.
“…Can I stay here tonight?”
The cold mafia boss softened instantly.
Without a single question—
He opened his arms.
And somehow that simple gesture made your chest ache more than expensive gifts ever could.
You curled beside him silently.
His warmth surrounded you immediately.
After a while, Heeseung spoke softly into the darkness.
“You’re safe here.”
Your fingers tightened slightly around his shirt.
“I know.”
And for the first time in years—
Heeseung truly believed it too.
───
It was almost three in the morning when you found Heeseung awake again.
The mansion remained silent except for rain outside.
You entered his office quietly carrying tea.
“You haven’t slept.”
Heeseung rubbed his eyes tiredly.
“Work.”
“You said that yesterday too.”
He accepted the tea from your hands carefully.
Always carefully with you.
You sat across from him.
“What are you even doing?”
“Tracking shipments.”
"That sounds suspicious.”
“It is.”
You laughed softly.
And Heeseung’s eyes immediately lifted toward you.
Like he was unconsciously drawn to the sound.
“You know,” you said quietly, “you smile more now.”
A faint expression crossed his face.
“Only around you.”
Your heart betrayed you instantly again.
“You say dangerous things so casually.”
“I mean them casually.”
You shook your head while laughing softly.
Then after a moment—
“Do you regret meeting me again?”
Heeseung looked genuinely stunned by the question.
“No.”
“Even after all the trouble I cause?”
“You’re the only peaceful thing in my life.”
The room became quiet.
Heavy.
Emotional.
Then he suddenly stood and walked toward you slowly.
His large hand gently tilted your chin upward.
“You know what scares me?”
Your breathing slowed.
“What?”
“That one day you’ll realize you deserve someone better than me.”
Your chest hurt hearing that.
Because beneath all his power—
All his violence—
Heeseung still carried the lonely boy from the rooftop.
The boy who believed people eventually left him.
You reached up carefully and touched his cheek.
“I already chose you.”
Something vulnerable broke open inside his eyes.
And then—
Very gently—
He kissed you.
Slow.
Careful.
Like something precious he waited years to have back.
Outside, Seoul continued sleeping beneath rain and crime and darkness.
But inside that quiet office—
Lee Heeseung finally allowed himself one impossible thing.
Happiness.
