Disclaimer: All sexual activity is between fictional characters over the age of 18.
~~~~~~~~~~
It was the summer after I graduated from college. I had lined up my first job in my professional career in my home town, but was still going to be living at home with my parents and younger sister Shannon, trying to save up money for my first apartment. After my older brother Mark had moved out two years earlier, my parents started making plans to combine their bedroom with his into a full master suite, and they began construction after Christmas break, when Shannon and I were both at college, Shannon in her freshman year, and me in my last semester. The construction was completed before I graduated.
My parents both worked really hard at their jobs, but we had stayed in a four bedroom, one-and-a-half bath house well after they could have afforded to upgrade, but they instead put their money into our college funds, and after having set aside enough to pay for Shannon's next three years, and with Mark gone, they could finally afford to upgrade the existing house, and I was really happy for them, as they gave Shannon and me our first tour, after getting home from my graduation.
Growing up, the arrangement of the bedrooms upstairs was the doors to Mark's bedroom and my parents' bedrooms on the left, mine and Shannon's on the right, and the door to our one upstairs bathroom at the end of the hallway. The bathroom jogged to the right behind Shannon's room, giving my parent's bedroom more space, and the main purpose of the upgrade was to add a second full bathroom. It had been tough for five of us to share one shower/tub, as the downstairs bathroom only had a toilet and sink. I know, a lot of the world would like to have that problem, but a second full bath would definitely be better.
Dad opened the new french doors that had taken the place of both Mark's and their old ones, and announced, "Ta-daaa!" Mom and Dad's bed was opposite the doors, and they'd upgraded to a California King. To the right were the new bathroom and a walk-in closet, and to the left, using about half of the space of Mark's old room, was a small TV/media space, with a wide-screen TV and a love seat opposite it. The contractors did such a great job that you couldn't tell it had once been two rooms.
Shannon and I walked around a bit, when Shannon squealed, "Is that a whirlpool tub? Can I use it? Please? Pretty please?"
"Maybe once in awhile, sweetie," Mom said.
"This was an upgrade for us, June," Dad said. "The kids get to benefit from not having to share their bathroom with us any more."
"C'mon, Jack, lighten up," Mom said. "So long as she asks permission, and we're not going to be in the bedroom, I don't see the harm, so long as she cleans up after herself. Clear, sweetie?"
"Thanks, Mom," Shannon said.
"Did everything turn out just like you hoped, Dad?" I asked.
"Only minor problem we still need to get the contractor to come back and fix are the doors. Look," he said, closing them. "There's supposed to be a moulding on one door, to cover the edge of the other, when they're closed, and you close that one last and latch the other at the top. Instead, we have this gap between the doors, where they don't quite meet each other. See? Otherwise, they did a perfect job on the whole project, which is amazing. C'mon, Jamey, Shannon, let's go get your stuff unpacked from your cars, okay?" Shannon had finished her classes before my graduation, but had just driven her loaded car from her college to mine, and stayed with Mom and Dad at a hotel before my ceremony, so she'd just gotten home, too.
--
Six nights later, we had all gone to bed, when I needed to pee. I got up and walked to the old bathroom, closed the door before turning on the light, and did my business, and likewise turned off the light before opening the door again. On the walk back to my room, though, I heard a woman's moan, and it was coming from my parents' room. I stopped next to the doorway, and could see light through the very gap between the doors that Dad had been complaining about. And more than that, I could see my Dad's bare butt, rising and falling on Mom, her legs wrapped around him, the covers bunched up at the foot of the bed keeping me from seeing his dick go in and out. My parents were fucking, and I could see most of it, even with their doors closed. My cock started reacting immediately.
"Fuck me, Jack, harder," I heard my mom say, very, very clearly. Now, sure, I'd heard my parents making love before, it's not like their bedroom was hundreds of feet away, but the sound was always very muffled by their bedroom door. Their old door. Nothing like this. I swear I was hearing the squish of Dad entering Mom, again, and again. My dick reached full hardness with that thought.
I was almost rooted to the spot, shifting on my feet only enough to change my viewing angle a little, to see more of them through that gap. There! I could see mom's untanned breast under Dad's arm. Gawd, I never imagined that's what they would look like lying down. She had D-cup breasts, according to her bras. The one I could see was much firmer than I expected, only sagging to the side a little bit. I could make out her engorged nipple, in the center of a wide areola. I saw Dad clamp his hand over it, to squeeze the nipple between thumb and forefinger, and I felt pre-come ooze from my dick's head. This beat any porn I'd ever seen.
I saw Dad lower his head to suckle on that same nipple, when, suddenly, there was a hand clamped over my mouth from behind, another arm in front of my abdomen, and I was being pulled away from the doors by Shannon, walked slowly backward to her bedroom. I could have fought her off, but not quietly, so I cooperated with her moves. Once through the doorway, she quietly pushed her door closed behind us and turned her light on.
"Shan, I... I can explain..." I started to whisper, turning to face her.
"Watching Mom and Dad fuck turned you on, too?" she whispered back. Shannon was smiling at me, looking down at the obvious tent in my sleep shorts, and the dark spot where precum had soaked through.
"Yes... umm no,... I mean..." I stammered, not whispering, but speaking quietly, nonetheless. "Wait, what do you mean, 'too'? You...? You've watched them?"
She tittered softly. "Yes, brother. Two nights ago. And I heard them the night before that, but didn't watch. I don't know what it is, but I never remember Mom and Dad being this... frisky before."
"Maybe because this year was the first time in 25 years that none of us kids were living at home. They've probably fucked like bunnies since you started college, and why stop just because we're home for the summer?"