My sister, Erin, was nearly a year younger than me. Not quite a year. Our parents evidently had a pretty good sex drive and couldn't wait long.
Erin had always been a pretty hot looking girl. She was always well built - even in grade school she was thin and taller than most of her classmates, and was among the first girls to start developing a shapely ass and breasts. Once her breasts started developing they kept on going. By the time she was 16 they were at least as big as the average woman's.
I noticed her developing, but I was never attracted to her sexually. She was my sister! It never occurred to me that she was a girl like the other girls who took so much of my time, in fantasies or real life. Even when my friends would make comments about her looks, I didn't think of her that way. When someone made a crude sexual comment about her, I threatened to beat the shit out of them, defending my sister's honor. Still, even though I knew other guys saw her that way, I did not. I noticed other girls. I made crude sexual comments about them. And I never realized that I was doing the same thing to someone else's sister.
As for me, I was also tall and well built. Our family had good genes. I took after my dad, with the same brown eyes and wavy brown hair that he had, though I grew my hair longer. I was athletic, but most of my physical looks were inherited. And it came in handy with other girls. I was popular, and though no Romeo, I had screwed a few girls. Yet I expected Erin to remain a virgin. She was a girl, and she shouldn't do that stuff. Yeah, I know, it was sexist. But I meant well.
By the time Erin was 18, she was a knockout. Large, heavy breasts, small waist, great ass, and legs that wouldn't quit. She was very attractive. Men as well as boys turned their heads when she walked past. Her deep blue eyes and long blonde hair completed the package. Still, I saw her as someone to protect, not someone to desire.
I had a good job, but still lived at home because it saved me so much money. Not a bad thing for a guy who just turned 19. I also had no steady girlfriend, so I needed no place for regular sex. On the few occasions when I got lucky, it was usually in a car or at her place. But most of the time I was on my own. Yes, that's what I mean. Masturbating. And that's what started it.
One evening I was in my room, as usual, daydreaming and fantasizing, giving myself pleasure. I was nude and had slowly worked my erection to its full size. It was a night that I was going slowly, not in a hurry to cum. Suddenly I heard a noise. Was it a gasp, a moan? I wasn't sure, but I swung my head toward the door and caught a glimpse of my sister. My sister! Shit, not my sister! Then I realized that my door was open. I always close my door, always. She had to have opened it herself, then saw me stroking my cock.
These thoughts flashed through my mind, and my erection softened like the air had suddenly escaped. I was completely confused. I couldn't even think straight. My sister had seen me jacking off!
After I calmed down a little, I realized that I had to do something. I slipped my boxers on and went to her door. I knocked softly, as our parents were asleep. When she didn't answer, I opened the door slowly. She was sitting cross-legged on her bed, staring at nothing. I stepped in and closed the door, and said we should talk.
She nodded her head and I walked over and sat beside her on her bed.
"I'm so sorry I walked in on you." she said, very upset.
"Don't worry. It's okay. I just really didn't expect it. Are you shocked?"
"I was very surprised." she said, with just a slight hint of a smile. Then completely serious again she said, "Something else shocked me."
I tried to think what else would have shocked her more than seeing her brother jacking off. "What was it?"
"Never mind," she said.
"No, really, what was it?" I repeated. "You know you can tell me anything." We weren't that close, but closer than most brothers and sisters. And when we were serious, we always told each other the truth.
"I'm too embarrassed to tell you."
"Embarrassed?" I said. "You just caught me masturbating. I think I would be the one who is embarrassed."
"That's the problem. I know I caught you. I saw you. I saw your ... thing." She hesitated, not knowing what to say. "I can't tell you."
"Erin, come on. What can be so bad that you can't tell me?"
"I liked it!" she blurted out.
I was confused. "What do you mean?"
"I saw you, and I liked it!." She then said, much quieter, "It turned me on."
