...Suddenly changed your mind. No harm would be done if you, well, experimented a bit right? You could talk to your sisters later... You begun moving towards Jenny. Two reasons for that, one, you already had antagonistic relations with her, so you wouldn't feel bad taking advantage of her, and two, she, uhm, was taking a nap around this time.
You stealthily walked into her room. The sound of her steady breathing filling your ears. You hesiteted, it was your sister after all.
"It's for science." You murmured.
You started climbing on her blanket. Suddenly, the blanket began falling, with horror you increased you pace barely manging to fall on the bad.
Breathing with relief you looked up, shock and awe spreading on your face.
What you saw was Jenny's gigantic, naked body, you gulped heavily, you dong getting hard just from this sight. She lied on her stomach, her face peaceful.
You smiled wickedly, observing her. You lust conrinued to rise till you couldn't help yourself, climbing up her body. You looked at her two majestic peaks. Normally, they were medium sized, but now, they seemed like mountains. Their biggest plus, was how rounded they were. In fact, the third reason you went to Jenny was her looks. All your sisters were good looking, having similar genes passed from your parents, but she especially. Her personality on the other hand...
You finally scaled to the top, her soft flesh caving under your feet. You lied down, enjoying her warmth.
Haha, Jenny, if only you know you were gonna end up being violated by your big brother, your flesh between my legs! You started moving your hips, pounding her butt.
A fart escaped her ass, you could distinctly smell digested fish. The odor horrible, yet it only made you harder. Despite the riging bells in your hand telling you that your actions were rushed, you increased your speed.
Unsatysfied, you stood up, wishing for something more.