I was sitting in the living room, still half-asleep after my workout, when the door burst open and Liam walked in, with that sparkle in his eyes that only appeared when something really intrigued him. He was holding a notebook, as if he'd just slipped out of a lecture, but the energy radiating from him had nothing to do with anatomy.
He sat down next to me, too close for a casual conversation. I could feel the warmth of his thigh, a slight tremor, and the tension beneath his skin.
"I have a project," he said without a greeting. "For anatomy. It's more of a private presentation than an official study, but the topic is specific: the body's reactions to sexual stimulation under real-world conditions. Breathing, facial expressions, muscle tension, loss of control… everything."
I raised an eyebrow.
"Who do you need? Me?"
He smiled slowly.
"No. You'll be the one providing pleasure."
Those words sent a shiver down my spine.
"I need someone who really feels things," he added more quietly. "Someone who reacts more intensely than others."
He was silent for a moment, as if savoring what he was about to say.
"Jack."
It made sense. Jack always reacted quickly. He was loud, impulsive, giving up control in a second. His body was alive just beneath the surface of his skin, a glance, a touch, a suggestion, that was all it took.
"He's always horny," Liam said, not even trying to hide his fascination. "The perfect participant."
I nodded.
"All right. You can count on me."
Liam exhaled, as if he'd just been given the go-ahead for something more than just a project. He stood up, and I followed him. He knocked on Jack's door once, lightly but firmly. A moment later, the door opened.
Jack stood in the doorway, disheveled and slightly sweaty, as if he'd just finished a workout or something he didn't intend to talk about. Liam presented the idea. He used the words "experiment," "reactions," and "pleasure."
Liam looked at Jack more seriously.
"Just to be clear: this isn't just observation. Matt will be touching you. Sexually. Only as much as you want. If you say stop, we stop immediately."
Jack didn't even flinch. He looked first at Liam, then at me, and that provocative, hungry amusement appeared in his eyes.
"I know what I'm getting into," he said calmly. "And I want this."
That's when something clicked inside me. I saw the way Jack was looking at me from under his lashes. I also saw how Liam was glancing at our bodies, how his breathing was getting shallower.
And I already knew this wasn't going to end as just an academic exercise.
Liam glanced at his notebook.
"It'll be best if you undress. I need to see the reactions of your muscles and skin."
Jack raised the corner of his mouth.
"Sure."
Jack sat down on the bed without a hint of hesitation. He grabbed the bottom of his T-shirt and pulled it over his head in one smooth motion. His chest muscles tensed in the light, his shoulders broad, his arms confident, his body ready, as if it were just waiting for a command.
Then he unbuttoned his pants. Slowly, but not out of shyness. More like someone who knew he was being watched and liked it. The fabric slid down his hips, revealing his strong thighs and toned stomach.
I held my gaze a little longer than I should have.
Jack noticed.
His cock twitched before I'd even touched it with a finger. It was reacting to the attention itself. To me.
Liam stood nearby with his notebook, but his breathing had stopped being calm.
"I need complete freedom of observation," he said suddenly. "Matt… maybe you should take your clothes off, too. Jack will feel more at ease. And I'll be able to compare the reactions better."
It was just a pseudo-scientific excuse.
But I liked this game.
I stood in front of Jack. His eyes immediately drifted downward, as if he couldn't help himself. I grabbed my T-shirt and slowly pulled it over my head. I could feel both of them taking in the sight of my body, my stomach, my chest, my arms.
When I tossed the shirt onto the floor, Jack swallowed, and his cock twitched a second time.
Liam cleared his throat and jotted down:
"Increased erection in Jack after Matt removed his clothing. Strong visual reaction."
Jack let out a short chuckle.
"Are you really writing that down?"
"It's for the project," Liam replied.
But when I looked at him, I saw his dilated pupils. These weren't academic notes. This was someone discovering that what turned him on most was a real physical reaction, not theory.
I slid my pants down slowly, deliberately. The atmosphere thickened. There was no longer a room, a bed, or walls. There was only breathing, tension, and three guys pretending it was all for science.
Liam stood by the desk, straightening his notebook as if that would restore the seriousness of the situation.
"Stage one," he said in a calm, lecturing tone. "External stimulation with the hand. Matt will be making the movements. Jack will describe what he feels."
Jack sat down as Liam had indicated, leaning against the headboard, legs spread wide, hips slightly thrust forward. His cock was already hard, throbbing, as if my mere presence were half the battle toward losing control.
I sat down close to him. So close that he could feel my breath on his stomach.
I placed my hand on his thigh. Gently at first, just enough for his body to register the contact.
Jack flinched.
Liam noted:
"A sudden increase in thigh tension."
I moved my hand higher. I could feel the warmth of his skin, the tension in his muscles, that slight tremor that precedes pleasure. Only then did I close my hand around his cock, slowly, confidently, exactly the way I liked to take the lead.
Jack exhaled more sharply than he intended.
"You're breathing faster," I murmured, sliding my hand downward. "And we haven't even gotten really going yet."
His first moan was short, low, and uncontrolled.
"Jack," Liam said. "Where do you feel it the most? In your stomach? Your thighs? Your breath?"
Jack tried to answer, but I changed my grip. The gentle pace gave way to a more deliberate, guiding rhythm.
"H-here…" he gasped. "In my stomach… and… I don't know…"
He faltered as my thumb slid over the sensitive part of his head.
"I'm writing it down," Liam said, but I could hear fascination in his voice.
Jack tilted his head back, his eyes half-closed. His hips rose instinctively, as if he wanted to match my rhythm. His body was a book I could read without words, the pulsing beneath his skin, the tension in his stomach, the trembling of his legs, every detail told me more than his answers.
"Focus on my hand," I said quietly. "And on how your body is reacting."
Liam was writing.
Jack's breathing grew heavier and heavier.
I changed the pace. The gentle rhythm gave way to slower, deeper movements of my hand, the kind Jack could feel with his whole body, not just between his legs. His breath caught immediately.
"Take it easy," I murmured.
Jack bit his lip. His abdominal muscles twitched beneath my fingers. He looked as if he were trying to keep himself in check, but his body had long since made the choice for him.
I sped up for just a few seconds.
It was enough for his fingers to clench the sheet so tightly that the knuckles turned white.
Then I slowed down again.
And that broke him more than the acceleration had.
"On a scale of one to ten..." Liam spoke up, trying to sound calm, though his voice trembled. "How much pleasure do you feel at this pace?"
Jack opened his mouth, but then I pushed harder with my hand, guiding his hips where I wanted them.
"Nine… no, wait…" he mumbled. "I don't know…"
Liam was taking notes, but he was gripping the pen too tightly to feign indifference.
"What do you feel right before your hips slip away?" he asked.
Before Jack could gather his thoughts, I slid my thumb under the head, lightly, in control.
Jack's body reacted immediately.
"I don't know…" he moaned. "It's… just…"
That was exactly the point. The point where words no longer exist. Only reactions. The moment when the body speaks faster than the tongue.
Jack tilted his head back. His abdominal muscles tensed in waves, his thighs trembling to the rhythm of my hand.
"That's the moment, isn't it?" Liam asked, his voice already hoarser.
Jack tried to answer, but all that came out was a deep, breaking moan. His hips thrust forward, as if his body itself wanted to admit the truth.
Liam jotted down quickly:
"Uncontrolled reaction. Hips moving on their own."
I smiled to myself.
I picked up the pace. Not abruptly. Deliberately. Just the way I liked to do it once I knew how someone's body breathed beneath my hand.
His hips moved to the rhythm I was setting. He was breathing fast, heavy, louder and louder.
I moved closer, until our bodies were almost touching, their warmth mingling.
"Breathe," I said quietly.
Jack gasped for air.
My hand picked up the pace once more. More confidently. Deeper. More precisely.
And then I felt it, that distinctive muscle spasm. His hips jerked so sharply that I had to steady him with a hand on his hip.
"Hold on," I muttered.
His body tensed like a string.
And it snapped.
Cum hit his chest and stomach, then spilled over my hand. Jack moaned louder than he had throughout the entire experiment. His voice was low, hoarse, completely surrendered.
Liam stood nearby with his notebook, but for a few seconds he didn't write anything.
He just watched.
Only when Jack was still trembling did Liam finally whisper:
"Release occurred at an intensity of nine out of ten… full, uncontrolled response… Matt successfully triggered the reaction…"
His voice trembled on the last word.
I looked at him.
He looked at me.
In that gaze, there was no longer just the project, the charts, or the notes.
There was also the fact that we had both seen how naturally Jack responded when I took the lead.
And that Liam wanted to see what would happen next.
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