Y/n's POV

The rain drummed against the windows as I watched Jungkook flip through his notes, his perfect fingers tracing lines of text I couldn’t read from this angle.

“Hormonal regulation,” he said, not looking up. “The menstrual cycle, let's start there.”

“I know the menstrual cycle.”

“Do you?” He said while lifting his eyes. “Tell me about the luteal phase.”

I recited it like I was in an exam. “After ovulation, the follicle transforms into the corpus luteum, which secretes progesterone to maintain the uterine lining. If fertilization doesn’t occur, the corpus luteum degenerates, progesterone drops, and menstruation begins.”

“Textbook perfect.” He set down his highlighter. “Now tell me what it feels like.”

“What?”

“The hormone crash before your period. You’re a woman and you've lived it so tell me what it feels like in your body and not in your textbook.”

My throat tightened. “Why do you want to know that?”

“Because I want to know everything about you, Y/N.” He said it so casually like he was discussing the weather. “And because this project is about reproduction, which is about bodies, which is about sensation. You can’t understand the system if you don’t understand how it feels.”

I shifted on the couch and pulling my knees up. “It feels like everything is too much and not enough at the same time ...Like my skin is too thin.....like I want to cry for no reason.... like I want to punch something.”

“And the ovulation phase?” His voice dropped. “What does that feel like?”

Heat crawled up my neck. “You know what it feels like.”

“I want to hear you say it.”

My fingers curled into the fabric of my sweatpants. “You feel… open. It's like your body is begging for something it won’t admit to.”

“And do you feel that now?”

The question hung between us. I could lie. I should lie. But his eyes held mine and the words came out before I could stop them.

“Why? Are you offering?”

Jungkook’s breath caught. I...i fucking saw the tiny hitch in his chest and the way his fingers stilled on the textbook. Then he smiled slowly.

“I’m offering a demonstration,” he said. “If you’re brave enough to take it.”

“A demonstration of what?”

“Of how well I understand the material.” He leaned forward and the guarded zone of textbooks between us suddenly felt like nothing. “Let’s make a deal. the first one to make the other moan wins and winner takes lead on the project.”

“That’s ridiculous.”

“It’s science. We’re testing a hypothesis.”

“What hypothesis?”

“That you want this as much as I do.” His voice was low and intimate. “That all this fighting is just foreplay.”

I should have said no. I should have laughed it off, called him an idiot, thrown him out into the rain. But the word that left my mouth was, “Fine.”

His pupils dilated. “Fine?”

“Fine. But when you lose, you’re buying coffee for every study session for the rest of the semester.”

“And when you lose” , he leaned close enough that I could smell the rain still clinging to his hoodie “you’re mine for the entire project. No arguing or fighting and You will do what I say.”

“I’m not agreeing to that.”

“Too late.” His hand moved slowly and landed on my knee. “You already said fine.”

My breathing stopped. His palm was warm through the thin fabric of my sweatpants, his fingers curling slightly....testing my patience.

“I get to make the first move,” he said. “Since I proposed the experiment.”

“That’s not how -“

“Shh.” His thumb traced a circle on my knee and my sentence was cut short. “Just feel for now .”

His hand slid upward achingly slow, pushing the fabric of my sweatpants as he slid upward. My thighs parted before I told them to... a betrayal of everything I’d been trying to hide.

“That’s it,” he murmured. “Good girl.”

The words hit deep, his fingers reached the hem of my shorts beneath the sweatpants, at the elastic edge of them and then he paused.

“Tell me if you want me to stop.”

I didn’t. I couldn’t. My throat was closed, my lungs were burning and my entire existence narrowed to the point where his fingers rested.

He hooked a finger under the elastic , pulled it and let it snap back against my skin.

I gasped.

“Sensitive,” he observed and there was as satisfaction in his voice. “Noted.”

He withdrew his hand and I almost whimpered at the loss. He shifted off the couch and settled onto his knees on the floor in front of me.

“What are you - “

“I’m taking the lead.” He gripped my ankles, pulling my legs straight then draped them over his shoulders. “You wanted to know what ovulation feels like? I’ll show you.”

His fingers found the waistband of my sweatpants again and this time he pulled them down slowly, deliberately, exposing my legs to the cool air of the apartment.

The shorts were off and then I was bare from the waist down, and Jungkook was kneeling between my thighs looking at me like I was the answer to a question he had been asking for years.

“You’re beautiful,” he said and the sincerity in his voice made my chest ache. “Do you know that? Do you know how long I’ve wanted to see you like this?”

“Since freshman year,” I whispered.

“Since before that.” His hands slid up my thighs, spreading them wider. “Since the first time you told me I was wrong in that seminar. Since you looked at me like I was beneath you and I knew I had to have you.”

His head lowered and his breath ghosted over my skin, warm , and I fisted my hands in the couch cushions.

“Tell me you want this,” he said. “Tell me you want me.”

“I want you.”

The words came out raw and honest in a way I’d never been with him before. He made a sound , low and pleased and then his mouth was on me.

His tongue was warm, dragging up through my folds in a slow, exploring stroke. My back arched, a sound escaping my throat that was half gasp, half moan.

“There it is,” he murmured against me. “But that’s not enough , I want a real sound .”

His tongue circled my clit, once, twice, then flicked sharply. My hips bucked and his hands clamped down on my thighs holding me still.

“You take what I give you.”

He set a rhythm , slow circles, quick flicks, long flat strokes that made my vision blur. I was wet, embarrassingly wet, and he was making it worse and better, making me forget every reason I had for keeping him at arm’s length.

I bit my lip hard , trying to hold back the sounds building in my throat.

“Don’t you dare,” he said, pulling back just enough to look at me. His chin was slick and his lips swollen, eyes dark and hungry. “I want to hear you. I want the whole campus to know that Jeon Jungkook made you moan.”

“You haven’t won yet.”

His smile was sharp. “Give me five more minutes.”

He lowered his head again and this time he was relentless. just his mouth on my clit, sucking hard, his tongue flicking in a pattern that made my thoughts scatter like leaves in wind.

The pressure built low in my belly, spreading outward while making my toes curl. I was going to lose. I was going to lose and I didn’t care because his mouth was magic and his hands were iron and I had never felt so completely undone in my life.

My hands found his hair, fingers tangling in the dark strands and I pulled.

He groaned against me, the vibration sending shockwaves through my entire body. That was it....that was the moment. A sound escaped me, high and broken and utterly shameless...a moan that filled the apartment and drowned out the rain.

Jungkook pulled back grinning, his face flushed and triumphant.

“I win.”

I was still trembling and still gasping, trying to remember how to form sentences. “That was....that wasn’t fair.”

“All’s fair in love and biology projects.” He rose onto his knees, leaning over me while caging me against the couch cushions. “Now it’s my turn.”

His turn. The words took a moment to register. His turn meant I had to make him moan. His turn meant I had to touch him.

I sat up while pushing against his chest until he sat back on his heels. “My turn,” I corrected. “You had yours and now I get mine.”

His eyebrows rose. “You want to make me moan?”

“I want to win.”

I pushed him onto his back and he let me. He sprawled across my living room floor with a look of amused surprise. I crawled over him as I settled my weight on his hips, feeling the hard line of his arousal through his jeans.

“Fair warning,” I said whilst unbuttoning his jeans with fingers that still trembked. “I’m competitive.”

“I know.”

I pulled his jeans down.... then his boxers, and then he was bare beneath me, hard and beautiful. My mouth went dry.

He was long, thick, the skin flushed and tight. I wrapped my hand around him and he sucked in a breath.

“Sensitive?” I echoed his earlier question.

“Brat.”

I smiled. “Noted.”

I lowered my head, my tongue darting out to taste the tip of him. Salt and skin and something purely Jungkook. His hips bucked while a low sound rumbled in his chest.

“That’s not a moan,” I said.

“Give it time.”

I took him deeper, my mouth sliding down his length and this time I was the one setting the rhythm. I learned the way he twitched when I sucked, the way his breath caught when my tongue traced a particular vein, the way his hand fisted in my hair when I took him all the way to the back of my throat.

His composure cracked. His hips moved ; thrusting into my mouth with growing urgency and the sounds he made - low, broken and desperate were the most satisfying thing I’d ever heard.

But still , there was no moan.

I pulled back, breathless and looked up at him. His chest was heaving, his eyes dark and glazed ; his lips parted.

“Close,” I said.

I moved up his body, my mouth trailing a wet path up his stomach , then his chest and then his throat. I paused at his jaw, nipping lightly and he shuddered.

Then I leaned in, my lips brushing his ear and whispered, “I want you inside me.”

The moan that tore from his throat made my heart thud strongly in my chest. He flipped us in one fluid motion, pinning me beneath him .

“You win,” he said . “You win. Now let me have you.”

I wrapped my legs around his waist pulling him closer. “I thought the winner takes lead.”

“You took lead.” His forehead pressed against mine. “Now let me take you.”

His hand slid between us, guiding himself to my entrance. He paused there just barely pressing while his eyes locked on mine.

“Say my name.”

“Jungkook.”

“Say it again.”

“Jungkook.” I arched into him, desperate for more. “Please.”

He pushed inside me in one slow devastating thrust and the world narrowed to the feeling of him filling me completely. My nails dug into his shoulders, a cry escaping my lips.

He stilled, letting me adjust and his breath ragged against my throat. “You feel..fuck, Y/N. You feel incredible.”

“Move,” I begged. “Please move.”

He moved slow at first, long strokes that made me feel every inch of him, then he increased his pace, harder, his rhythm building like a storm.

The couch creaked beneath us as the rain hammered against the windows and I lost myself in the feeling of his body against mine.

His mouth found mine and the kiss was messy, all teeth and tongue and swallowed moans. I tasted myself on his lips and it was the most intimate thing I had ever experienced.

“I’ve wanted this,” he said against my mouth. “I’ve wanted you. For so long. So fucking long”

“Me too.” The admission broke free, honest and terrifying. “I’ve wanted you too.”

His pace quickened, his hand sliding between us to find my clit and the pressure that had been building since his mouth was on me finally shattered.

I came with a cry, my body tightening around him and he followed a moment later, his groan muffled against my shoulder and his hips stuttering as he spilled inside me.

We lay there tangled together and breathing hard while the rain slowly fading to a drizzle outside.

After a long moment he lifted his head, looking down at me with something soft and wondering in his eyes.

“That wasn’t just a project,” he said.

“No,” I agreed. “It wasn’t.”

He kissed my forehead gently and I felt something shift between us.

“We should probably study,” he said.

“Probably ”, I said but neither of us moved.