A step-brother's lust leads to taboo acts of masturbation.
I remember noticing how heavy they looked atop her flat stomach and thin waist, and how unexpected on a girl with rather slim thighs. She'd lost weight, so they looked obscene stretching out slightly beyond her slender upper arms, jutting out below her narrow innocent face. It was obviously she was a few cups bigger than a DD, though I wouldn't learn until later that semester than she was a 32H cup.
I should mention here that I have always been fascinated by other busty girls. I first realized that breasts can get really big, even on otherwise thin bodies, around the time I was 15 and my older cousin was changing in front of me for a party. I remember being absolutely transfixed by the weight of her huge boobs on her tiny body. It seemed surreal, yet intensely arousing. This is also a good time to mention that although I consider myself straight and have only wanted relationships with men, from this time onwards, women's breasts and pornography highlighting voluminous busts have been the quickest and most satisfying way to arouse me. It may be a fetish of sorts, but I find very topheavy women incredibly hot and I have to control my gaze so that it's not excessively obvious that I am staring at them.
But back to Kylie. I remember feeling both awed by her incredible tits and intensely jealous. While I had a very attractive body at the time, smooth, tanned, and toned from an active lifestyle, with nice proportional curves, I had always aspired to the "slim and stacked" model that was simply not attainable. I remembered thinking that I would insist on meeting James at his place or going out, and not inviting him back because I did not want him to see Kylie. It sounds incredibly petty, but I was young, James was my first lover, and I knew that he had a ravenous sexual appetite. I also sensed that Kylie, who was, incredibly, still a virgin, despite her shyness, craved attention and was quite competitive with me.
We were both honors students, competed for grades, and developed a fashion rivalry that semester. I had always been into fashion, taking care of my appearance and wearing little dresses and skirts to class, and I noticed her envious gaze sometimes when I stepped out of my room. That semester, our very first living together, she shed the jeans and t-shirts for tight tops and miniskirts, low-cut dresses, and even halter tops for some parties. She usually denied being competitive with other women, but one night when we had been drinking together, she admitted to feeling jealous of some of her closest friends, including me, and wanting to outshine them in academics, looks, and relationships. I never forgot her confession, and for that reason, when she mentioned wanting to meet my boyfriend, I changed the topic or gave a vague answer.
I managed to keep James away from our apartment until October. One night, it was simply more convenient for him to come over to our apartment after work. Kylie had been casually dating someone and was supposed to be out, so I agreed to it. I met him at work and we went back to my place together. When we opened the door, I realized we weren't alone. I could hear rustling in Kylie's bedroom down the hall, and before I could do anything, she had emerged.
A strange tension engulfed us as she drew closer.