All characters in this story are 18+ years of age
****
I watched as my 20-year-old sister trudged into the kitchen, grunting a greeting and grabbing a bowl before sitting down opposite me. Julie was tall at 5'8", with thick, wavy brown hair that came to her shoulders.
"Good morning to you too, sister dearest," I replied jovially as Julie poured some cereal into her bowl.
Julie snorted. "Right. Why are you even up this early? It's not like you do anything all day anyway. Might as well sleep in."
It was true. I had just finished my last year of high school and was spending my summer enjoying life at home while Julie took summer courses at the local community college to finish up some prerequisites.
"The early bird gets the worm, as I'm sure they've taught you in your philosophy classes," I replied.
"Wow. Profound. You should really teach the course," Julie said, then began to eat her cereal.
We continued to eat in silence, until Julie finished and got up to get ready for school. I watched admiringly as the real reason I got up so early revealed itself. As Julie bent over to put her bowl in the dishwasher, the oversized shirt that she wore rode up and gave me a wonderful view of her panty-clad ass. Today she wore a thin, tight pair of pink boyshorts. Such images had plagued me with guilt throughout high school, but I'd eventually accepted that my sister was simply incredibly hot and now eagerly awaited these glimpses.
What had finally broken my defenses was when one morning Julie walked in wearing a tank top and a lacy black thong. The top hadn't even reached the panties, giving me an amazing view of her tight ass as she walked around the kitchen. Somehow she didn't seem to realize that what she was wearing was wildly inappropriate, even if only I would be seeing her. I guess she just always assumed that, as her brother, I wouldn't think anything of it. On the contrary, since that day I've rarely thought about anybody else but my sister as I masturbate.
As soon as Julie had left for her classes I went upstairs for the second part of my morning ritual. I let myself into Julie's room and fished through her laundry hamper until I found the boyshorts she'd just been wearing. I brought them to my face as I stripped my pants off and inhaled her scent, then wrapped them around my already hard cock, lying down on Julie's bed and began to stroke. Thoughts of my sister's ass and tits dominated my mind as I masturbated, and soon I was cumming hard into the crotch of her panties, which I then replaced in her hamper with the rest of the pairs I'd soiled this week.
****
I spent the rest of the day mucking about on my computer and watching TV. When Julie and our parents returned from school and work we ate dinner together, after which Julie asked if anybody wanted to watch a movie. Both of our parents declined, but I accepted.
"Great. You find something, I'm just gonna have a shower and then I'll be back down," she said, then headed upstairs.
She came back down as I was deciding between two movies, with wet hair and her usual pyjamas. Tonight they consisted of a shirt that had probably been overlarge a couple years ago before she shot up four inches, but was now only a bit too big. A pair of red bikini panties poked out beneath the shirt, which I quickly noted before focusing back on the TV.
"Comedy or action?" I asked.
"Action," Julie decided after a moment's thought. I nodded, then set the movie to play. She sat down with her back against an arm of the couch I was sitting on, stretching her legs and placing them in my lap.
The movie was pretty mindless, which was good, since I was balancing my concentration between that and keeping down an erection she'd be able to feel for most of it. I had a pretty good view of her her panties from this angle, and I spent a good part of the movie thinking about how I'd be using them tomorrow morning.
After it ended we both headed upstairs to go to bed. I managed to stay a couple steps behind Julie, giving me a great view of her butt bouncing as she walked up the steps.
****
The next morning found me once again on Julie's bed, her red panties from last night wrapped around my cock. My eyes were closed, imagining pulling her panties aside and fucking her over the kitchen table. I'd gotten quite the eyeful this morning to fuel my fantasy.
"What the fuck?" I suddenly heard my sister shout. My eyes shot open. "What the fuck are you doing in my bed? Are those... Are those my panties?"
Julie stood in the doorway, a look of utter shock on her face as she stared at me.
"Julie! What-" I managed to gasp, and then I came. It was the most intense orgasm of my life up until that point. It must have lasted almost fifteen seconds, which I spent with my mouth hanging open, looking at my sister's face, unloading huge amounts of cum into the red cloth around my cock.
"What- what are you doing here?" I stuttered dumbly after the orgasm subsided.
"I forgot my phone. But I think I should be the one asking that question, don't you?"
I tried to think of something - anything - to say that could make this situation any better, and came up with nothing. I looked down in shame.
"Y'know what, I'm late for class," Julie said exasperatedly. "This is really weird, but I gotta go. We'll talk about whatever this is when I get back." She picked her phone up from her dresser and walked back out the door, looking over her shoulder at me as she left with a confused look on her face.
I fell back onto her bed, hand leaving my dick, which had remained hard throughout the encounter. "Fuck. Fuck fuck fuck," I thought. I knew Julie only had one class today, which meant she'd be back in a couple hours. I had no idea what I'd say to her, and what's worse, all I could think of at that moment was masturbating again. I looked at the panties, which were essentially just one giant cumstain at this point. Not really knowing what to do with them, I threw them back into her hamper.
I decided to take care of my erection first, as so much adrenaline was pumping through me that I could hardly think. When I still wasn't able to cum after twenty minutes, I decided that my situation couldn't get any worse and opened Julie's panty drawer. I fished out a pair of pale pink panties I didn't think she'd notice missing,then began to stroke them against my cock. I didn't cum nearly as much as I had earlier, but it was still a sizeable load, and it shared some of the intensity of before. I hid this pair in a drawer in my room, got dressed, then sat down to wait.
****
A couple of hours later I heard my sister come in and head to her room. After a few minutes of silence, she called for me.
"Justin? Could you come here?"
Heart pounding, I slowly left my room and walked to her doorway. I glanced at her, then down at the floor. I couldn't hold her gaze.
"You wanna explain this?" she asked, voice neutral, and pointed at something on her bed. I realized she'd fished out all the panties she'd worn this week and laid them out on her bed, even the still damp red ones from this morning.
