Somehow, he doesn't

You start slow—gentle rocks of your hips, riding him with careful, measured movements to keep him asleep. The friction is exquisite, his cock dragging along every sensitive spot inside you, building the pleasure without rush. Careful now - a couple of thrusts is all it's gonna take to tip him over the edge. Just release his pain, he must be so pent up. You think to yourself. I gotta take care of my brother, don't I? He needs this.

He groans softly in his sleep, hips twitching up instinctively to meet your rhythm, but his eyes stay closed, lost in his dream.

The build is agonizing and perfect—your clit grinding against his base with each roll, the curse's nagging pull finally sated as you gave into its temptation and chase your peak quietly. You feel his cock start to throb inside you. Not much longer now. Two more slow, agonizing thrusts, his cock starts trembling - and finally it bursts like a dam. A torrent of cum hits the very end of your birth canal with impressive ****. Your lower body is flooded with a sticky warmth, his cock pulsing deep inside, hot ropes erupting without pause as his own dream-release takes hold. You feel every spurt, warm and thick, coating your insides, and you hold still, resting your mound directly on the base of his perfect cock, locking him in to take it all, letting it seep deep.

With your brother's load finally deposited inside, you lift yourself on shaky legs off his stick. As soon as his cock leaves your freshly inseminated pussy, his load tries to escape. You press your palm against your swollen lips to seal your entrance with its precious cargo inside. You pull your brother's sweatpants back up, give him a soft kiss on his forehead and slip away upstairs into your room. Locking the door, you plant yourself on your bed, putting your pillow under your hips. Letting his seed flow into your deepest core to take root you finally find sleep, the warm glow of your filled belly soothing you into blissful unconsciousness. By morning one of your eggs has been fertilized and implanted in your womb. You're pregnant. You're staying a girl.

You got so close to winning!