It was 2 days later, the entire family was driving two and a half hours for a camping trip.
That shouldn't have mattered, it was when we stopped at my aunt's house that fate opened the door.
Aunt Jodie, mom's sister, wanted us to bring a couple extra boxes, ended up being four actually, up to Grandma's, mom's mom, which was on the way and about half an hour before where we were going camping.
Dad said, "We'd love to, but they just won't fit."
A wicked idea popping into my head. I offered, "Quinn can sit on my lap for a couple of hours."
"Really?" Dad asked, surprised.
I glanced at Quinn, who was equally surprised, and nodded, "If Quinn is okay with it. I'll do anything for grandma."
"Me too." Quinn agreed, completely unaware of my plan. So we packed everything into the back seats, and I made it so the boxes would block Mom's view from the front passenger side and Dad's view would be equally limited with the mirror being utterly useless.
"You sure you two can sit like that?" Dad asked, "The second hour is all gravel roads and will be quite bumpy."
"I'm sure we will be fine." I said, as I sat down in the confined space... hoping it would be very bumpy indeed.
She laughed, as she awkwardly moved in and sat on my lap, holding her skirt in place.
Dad looked in and said, "Last chance or forever hold your peace." A statement he often used when he was giving us a chance to reconsider or we, as a family, were making a final decision.
"I'll suffer through it." I said.
"I'm the one suffering." Quinn said.
Dad closed the door for us and got in the vehicle.
Mom called out, as the car started moving, "Comfortable?"
I responded, "It's fine."
"Yeah, it's okay." Quinn agreed too, her body leaning back on mine. Her p'sy directly on my dick.
She moved around a bit trying to get comfortable.
As she did... my dick hardened my naughty idea stirring my loins quickly.
The idea was a crazy one.
Fuck my stepsister in the car.
I decided to start with sly the other two still potential options.
I would flinch my dick, every minute or so, directly on her ass and pussy.
"This is a bit uncomfortable." I said, as I moved my arms from the awkward position I had them and moved them around my sister and placed them on her legs.
Her back stiffened, just as Dad asked, "You two okay back there?"
"Just trying to get comfortable." I answered.
"How about you, honey?" Dad asked.
Her answer would tell me a lot.
She answered, "I'm okay."
"Let me know if you guys need a stop to stretch your legs or anything." Dad offered.
For the next ten minutes, I just allowed my hands to rest on her legs.
I resisted the temptation to move my hands up her skirt. I also continued to flinch my dick regularly... continuing to tease her relentlessly.
Tanya, after a few minutes of sitting there like a statue, reached down, which made her pussy grind on my d'ck and pulled up her purse.
She was on her phone for a few minutes, but from my position I couldn't tell what she was doing.
Dad warned, "Here comes the bumpy road. Do you two need a break?"
"No, keep going." I answered, speaking for both of us.
"Okay." Dad responded.
A minute later, I asked, "Quinn, can you lift yourself up for a minute?"
"Uh, sure" she said, lifting her ass up awkwardly.
I quickly unbuttoned my shorts, quietly unzipped them and fished out my completely hard dick.
I then said, "You can sit back down." As she did, I spread her skirt up so her pussy would land completely on my now released sword.
She gasped, loudly. "Oh my God."
"You okay, honey?" Mom asked.
"Um, yeah, I um just poked myself a little," she said, her face ruby apple red her cover up also humorous.
"Sorry," I apologized loudly. "I didn't mean to startle you so much."
"Do I need to stop?" Dad asked.