Pairing: Mafia!Kim Namjoon x Sister!Reader

Summary: Now that you're with your brother, you've to be more careful while bonding with each other. The universe can handle only one destructive force at a time.

Warnings: Getting caught with your hand in the cookie jar (not literally), height difference, mentions of a huge metaphysics book.

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"Take it off now, girl. Just take it off. I'm a master, baby with your bra" Namjoon heard you singing into the the slotted spatula as the pancakes were getting burnt. "I can help you slide those panties off."

"Now this isn't what I expected" he said, interrupting your kitchen concert.

"Woah, the hell, bro?" you asked before turning off the stove and looking at him. "Who are you?"

Casually, he leaned against the kitchen counter and grabbed the glass of milk placed there.

"Nothing important. I'm just your brother from another mother."

And boom, the kidnapping~

"So, you both are married?" you asked and the couple nodded. "Yes! I've been shipping you both for the past five minutes," you squealed excitedly.

"I'm a Superman" the guy, the one who kept playing with his fingers, said randomly as he stepped in front of the bed. "Taehyun, bring tough guy Soobin here. Namjoon hyung's sister is going to kill us by talking too much."

"Beomgyu, you can't say that she's annoying if you want to be alive" the Taehyun guy said, placing his hand on the elder's shoulder.

"And this bedroom is five times the size of my apartment. Is this a mansion? Because I'm sure that it is. And I know that y'all are that mafia gang the world fears, and Namjoon guy is your leader. I've seen the news a lot of times. By the way, can you place that gun aside? I'm not going to run away with so many men surrounding the place. And can I get a McFlurry with chicken nuggets? It's my birthday today and I'm starving for-"

You halted on your words as the bedroom door opened, revealing Namjoon guy who claimed you as his sister.

"Out" he said and the couple walked out of the room, closing the door behind them.

"McFlurry and chicken nuggets?" you asked while tilting your head to the side.

"We'll get you food that's made by our chef. But we need to talk before that" he said and you nodded, legs criss cross as you waited for him to speak.

"I'm your-"

"Wait. Let me guess" you interrupted him. "My mother died giving birth to me, and I never knew anything about my father. So, technically, you might be my brother from another mother" you stated.

"Yes, and I'm your half brother. My mother is dead too. Today's my birthday, just like yours. And you're not going anywhere after this, now that I see you've graduated university" Namjoon said, handing you papers. "The DNA test results. They match."

"How on earth did you-"

"I have my ways" he said. "And you're my only family, Y/n."

"So, like, you're not gonna let me go after this?" you asked and he nodded. "Well, I would rather be the evil's somebody, than to be a little nobody."

Time skip to night~

"Whiskey?" you asked and Namjoon shook his head as a no, drinking the orange juice.

"Oh, you're that guy in a party" you said and nodded to yourself before drinking the whiskey in your glass.

"So, why this celebration?" you asked again and your brother looked at you, placing the empty glass on the bar counter.

"I finally found my half sister, and it's our birthday today. Though you're three years younger than me" he said and your mouth performed a small 'o'. "And don't feel bad or anything. Our so-called father was a pimp and a scumbag who used women for his own needs. Just concentrate on the connection between us and how many years I spent searching for you."

"Like, even I feel that connection now, you know. I'd love to be your sister and I'll definitely love you being overprotective" you stated before jumping off the bar stool.

"I've always wanted a brother, and I've always wanted to get kidnapped by the mafia. Wattpad raised my standards high" you mumbled.

"One Virgin Mary" you heard Beomgyu say to the temporary bartender as he reached the counter with his husband and Yeonjun. "Please remove tomato" he added, making you laugh a little.

"I see that you have a love for Virgins" you commented before looking at Jungkook who was playing hot potato with Taehyung and Jimin.

Even Jungkook's father, who decided to visit his son today, was so handsome that you couldn't take your eyes off him. The Jeon genes are no joke.

Jin was in the kitchen, baking cupcakes for Hyuka, while Hoseok and Yoongi were making out on the couch in the living room.

What an interesting bunch.

"You introduced me to everyone. But where's that sobbing guy?" you asked, slurring a little because of the alcohol.

"It's Soobin. He's on a mission, and will be here tomorrow" Yeonjun said and you nodded. "Enjoy the mini house party now."

"Oh party party yeah!" you heard Jungkook yell out of the blue.

"Joonie" you called and heard two voices hum in response. "Namjoonie" you addedd and Yeonjun turned away.

"What is it?" Namjoon asked.

"Teach me how to ride a bicycle" you said and he blinked his eyes before accidentally ripping off the shirt button he was playing with.

"You don't know how to ride a bicycle?" he asked and you gave a sheepish and drunk smile.

"No one taught me" you said and your brother pouted before gradually smiling.

"My sweet little clumsy sister~" he cooed before pulling you into a bear hug. "But we've to be careful. The universe can't handle two destructive forces at the same time."

Several months later~

"I see that the library is your favorite place in the house now" Yoongi said randomly as you placed the ice cream tub back in the freezer.

"Please don't tell anyone yet" you said immediately, looking at him.

"Namjoon will eventually find out. And if he discovers that I knew all along, he'll kill me. I don't want to lose my precious life for you both. Duh" he muttered before grabbing the sprite bottle for Hoseok and leaving.

Pouting, you turned the kitchen lights off, walking through the dark hallways to the library.

Once you reached your destination, you bumped into a huge pillar. A familiar pillar.

You're 5' 3" and the pillar is 6' 1".

"Shorty" he said with a teasing smile and you huffed before turning the lights on.

"I'm not short. My height is just cute" you defended. "And this is no way to greet your girlfriend on the first monthsary."

"But I love your shortness" your boyfriend said. "Trust me. All men do"

"Then who will love tall girls? And if girls love tall boys, who will love short boys? This is so- Ugh!" you groaned in annoyance, feeling the pair of arms sneak around your waist, lifting you up and placing you on the table. "Soobin, I swear to-"

Your words were cut off as he smashed his lips on yours, wrapping your legs around his waist.

You felt his tongue trace your lower lip, making you part your mouth. Smooth mothertrucker.

For a moment, you thought about how he'd react if you forced his tongue back outside. But you didn't want to. The reason was simple.

Once you Soobin, you cannot Soobout.

Your mouth opened; so did the door to the library, and there stood your brother, all in his Ryan pajama glory, glaring at you both as you jumped off the table while Soobin pulled away hurriedly, unwrapping his arms that were around your waist.

Your boyfriend hid you behind him, meaning to protect you from the wrath of Kim Namjoon who scoffed before walking forward slowly with his jaw clenched in anger, chin protruding.

"If you both are making out behind my back, at least don't do it on my study table" he hissed, taking his huge metaphysics book, the one you were earlier sitting on, from the table.

Your brother grabbed your hand, dragging you out of the library. "You're sleeping in my room" he said to you as Soobin trailed behind like a lost puppy.

Once you were successfully brought to Namjoon's bedroom that was upstairs, the metaphysics book was thrown on the bed as he stared at you and your boyfriend.

"How long?" he asked as you both looked down at the floor, standing beside each other.

"Four weeks. We planned to tell you in a few days" Soobin answered for you.

"Still virgins?" your brother asked and you nodded your head quickly with your boyfriend. "Look, princess, I wouldn't be mad at you for dating my right hand man. You could've-"

Namjoon halted on his words as you hugged him with a pout on your face. "Sorry" you mumbled with puppy eyes, raising your head up to look at him since he was much taller than you.

"Just tell me, okay? And in the future, if he hurts you during sex or anything, physically or mentally, just tell me again. I'll make sure that his brains are splattered across the wall and-" he halted on his words as you snuggled your head into his chest, or mostly his stomach. He's taller than you!

He signaled Soobin to join the hug, and the latter walked forward shyly before slowly getting pulled into the hug.

Though your boyfriend was actually taller than your brother, he bent down for the elder who caressed both of your backs.

"Thank you, hyung" Soobin said in the hug, just before Namjoon started his lecture on how relationships are like a walk in the park. Jurassic Park. And how to be Alan Grant.