He barely manages

He’s already teetering on the edge, cock buried to the hilt inside your prone, sleeping body, every shallow rock of his hips dragging him closer to the point of no return. The heat, the tightness, the slick grip of your **** pussy is almost overwhelming. His breath comes in ragged pants against your neck, sweat dripping down his back, balls drawn up tight and aching with the need to release.

_Fuck… gonna cum… The thought flashes white-hot through his mind, followed immediately by a sharper, panicked one: If I cum inside her, it’s over. She’ll be stuck like this forever. Pregnant. My sister… carrying my kid._ The dark thrill of that idea surges through him, making his cock swell even thicker inside you, but guilt and fear claw their way to the surface at the last second.

“No… can’t… he's still my brother in there” he grits out through clenched teeth, fingers digging hard into the mattress on either side of your hips. His whole body trembles violently with the effort, muscles locked rigid as the orgasm barrels toward him. He feels the first unstoppable pulse start deep in his core, the clench that signals there’s no turning back.

With a strangled, **** groan, he wrenches himself backward—pulling out in one frantic, barely-in-time motion just as the first thick rope erupts from him. His cock slips free with a wet, obscene pop, the swollen head dragging along your slick folds for almost a split second too long. The first powerful spurt lands hot and heavy across the crack of your ass, streaking in a long, pearly line from the small of your back down over one cheek. The second jets lower, splattering directly onto your exposed pussy—coating your swollen lips and dripping down over your entrance in a messy, glistening flood. Pulse after pulse follows, his hand stroking himself frantically through it, ropes of cum painting your ass and pussy in thick, warm stripes that pool in the crease of your thighs and trickle slowly toward the sheets....