He cannot resist

His resolve shatters completely in that moonlit haze, the air thick with the mingled scents of your shared arousal—his salty musk and your sweet, feminine nectar creating an intoxicating fog that clouds his judgment, every inhale pulling him deeper into the forbidden. Heart hammering like a war drum in his chest, he moves with agonizing slowness, every motion calculated to avoid rousing you from your deep slumber. The bed frame gives a faint, protesting creak as he climbs onto the mattress behind you, his weight distributing carefully, knees sinking into the soft foam on either side of your legs. You stir faintly—a soft, sleepy murmur bubbling from your lips, your curvaceous body shifting instinctively onto your stomach in prone position, face buried in the pillow, ass lifting slightly as your legs part just enough in relaxation. It's like an **** invitation, your full, rounded cheeks presented to him, the slick valley between your thighs exposed and glistening in the dim light, the plump folds of your pussy winking at him with residual wetness from the day's suppressed tensions.

He freezes, breath held in his lungs, the cool night air brushing his exposed skin and making the fine hairs on his arms stand on end. This is wrong, his mind screams, a torrent of inner conflict crashing over him—that's my brother in there, John, not some random slut. If I cum inside... fuck, I'll knock my brother...sister? up, make this permanent. You'll be stuck as my sister forever, belly swelling with my kid... our kid. Breeding you like this, turning family into something twisted. The thought sends a sick thrill through him, mingled with revulsion, his stomach churning even as his cock throbs harder, pre-cum dribbling in warm threads onto your inner thigh. He tries to pull back, muscles tensing to retreat, but the heat of your body calls to him, the pregnancy risk a dark allure—no condom, raw, filling that fertile womb, sealing your fate as a woman, as his woman. He shakes his head minutely, sweat dripping from his brow onto the sheets with a faint patter, trying to hold onto sanity: Snap out of it, man. You can still just leave and sleep on the couch. Don't make it real.

Your breathing evens out again, steady and deep, the only sounds the distant tick of a clock downstairs and the ragged hitch of his own inhalations. His cock, thick and veined, throbs insistently in his grip, the tip already slick with pre-cum that drips in warm, viscous beads onto the sheets below. Against his inner voice he positions himself stealthily, aligning his body over yours without touching—yet. The heat radiating from your prone form is palpable, a magnetic pull that makes his muscles tremble with restraint, the breeding urge warring with guilt: Just the tip, then stop. Don't risk impregnating your own blood.

Slowly he lowers himself, the coarse fabric of his sweatpants whispering against the sheets as he tugs them down further. His free hand braces on the mattress beside your hip, fingers sinking into the cool cotton, while the other guides his swollen head to your entrance. The moment seems to last forever until at last his engorged tip makes contact with the velvety heat of your slick folds. Your labia parts easily around him like warm, yielding to the intrusion.

Oh god, so tight... perfect for breeding, the thought slips unbidden, horror and lust twisting in his gut as he bites back a groan, teeth sinking into his lower lip until he tastes the sharp tang of blood. He inches forward millimeter by millimeter, your pussy clenching instinctively around the invasion—tight, wet, and impossibly welcoming, the inner walls rippling with subtle contractions that milk him without your awareness. The sensation is overwhelming: slick warmth coating his length, the faint squelch of your arousal as he sinks deeper, the friction of your swollen labia dragging along his shaft like silk over steel. Pull out now, he pleads with himself, hips stuttering for a moment, the impregnation risk flashing like a warning—one spurt and it's done, transformation locked in, you pregnant with incestuous life.

He pauses halfway in, buried in your prone heat, sweat beading on his forehead and trickling down his temples in salty rivulets that sting his eyes. Your body adjusts around him, a soft sigh escaping your lips into the pillow, but your eyes remain closed, lashes fluttering faintly in dreams. The scent intensifies now—musky and primal, the heady mix of your juices and his pre-cum filling his nostrils with every shallow breath, making his head spin. He can feel every detail: the plush give of your ass cheeks pressing back against his hips as he settles fully inside, bottoming out with a barely audible wet smack; the rapid flutter of your heartbeat echoing through your connected bodies; the cool slide of the sheets bunching under his knees contrasting the feverish clamp of your core. Hold back, he grits internally, trying to summon willpower against the breeding instinct—don't cum, don't flood that womb with fertile sperm, don't make her carry my child and stay a girl forever.

With painstaking care, he begins to move—shallow thrusts at first, hips rocking in a slow, stealthy rhythm that minimizes the bed's creaks. Each withdrawal pulls a slick sheen along his cock, the cool air teasing the exposed skin before he glides back in, enveloped once more in your molten depths. The sensory immersion is total: the velvet grip squeezing him rhythmically, as if your sleeping body craves this violation, begs to be bred; the faint, wet sounds of flesh meeting flesh, muffled by the closeness; the warmth of your back rising and falling beneath him, your soft hair tickling his chest as he leans lower, inhaling the floral remnants of your shampoo mixed with the raw essence of sex. His balls tighten with each deliberate pump, drawing up against his body, the building pressure coiling low in his gut like a spring wound too tight, the conflict raging: Stop, you idiot—pull out before you impregnate her, before you ruin everything.

__

Deeper now, his pace imperceptibly quickens, the friction building to a delicious burn—the slap of skin growing just a touch louder, though still hushed in the night's embrace. Your inner walls flutter around him, a subconscious response that sends sparks up his spine, your prone form arching ever so slightly into the motion without waking. He's lost in it, the world narrowing to the slick, rhythmic slide, the heady scents, the tactile bliss of your curves yielding beneath him. The tension mounts, his breaths coming in hot, ragged puffs against your neck, muscles straining as the edge approaches. His cock swelling thicker inside you, pressed closely to the opening of your cervix. Veins pulsing, the telltale tingle spreading from his core as he's about to cum, teetering on the brink, desperately trying one last time to hold back the flood that could breed you, impregnate you, lock in the transformation forever...