Bed with Christie

Christie did her bathroom stuff then joined me in bed.

"That was nuts," she said, "You still believe Aunt Olivia doesn't realize?"

I shrugged. "She knows parts of it, like when she jerked me off to get my... sauce. She just doesn't put it all together. She's oblivious."

"Okaaay," Christie said, "Well I guess I took advantage of it as much as you tonight. It's just so much fun."

"Yeah," I said, "You should move in next year. Screw the dorms."

She smirked. We were laying in my under the sheets in my dark bedroom, not really able to see each other in the faint glow of a nightlight.

We were naked under the covers so I reached over and fondled my sisters big, plump breasts.

"Pervert," she said, "Cumming in your aunt, and you shot your cum on me too."

I rubbed her nipples under the sheet. "All within the rules," I said, "I didn't touch your pussy, and you didn't touch my cock."

She laughed, but didn't argue with me looking for ways to get perverted with her without breaking the rules. I knew she liked all of this as much as I did. We really were quite similar people, it seemed. Normally brother and sisters are polar opposites, and we did have the token gendered differences (she liked fashion, I liked football, etc.) but when it came to sex, we had a very similar libido. I kept playing with her boobs.

"Oh Mark," she said eventually, "Do you ever worry that this is too much? I know it feels good, obviously I enjoyed sex with Aunt Olivia too, and you being so horny for my body and touching me like you are... but isn't all of this wrong?"

"I guess," I said, "But I mean I'm not a bad guy. Aunt Olivia loves having us here. She was real lonely before I came and she likes having me here, she's made that clear. And I love you... even pretending to be your boyfriend, that felt so good. I'd be your boyfriend if you wanted."

She gasped, and it felt like her body was melting in my hands.

"But what about Aunt Olivia? She needs a boyfriend too," my sister said.

I smirked. "There's enough of me to go around, ladies."

She laughed. "What a humble guy," she said sarcastically.

I leaned in and kissed her, and she responded to it very hotly, kissing me back and rolling on top of me. We were naked so I felt her skin all over me, on my thighs, her breasts dangling onto my chest, her stomach pressed against mine. She pushed her tongue into my mouth and we made out passionately.

With us in this position I wondered if she was going to consent to sex finally, and I probably wouldn't have stopped her. My rock hard cock was poking at her, that was for sure, pressing up against her bald pubic mound as we made out. My sister's body was so sexual and absolutely on fire tonight, I could feel her heart thumping and smell her arousal.

I reached around and grabbed her ass, which seemed to be within the scope of the rules, and pressed her against me even closer while I fondled her cheeks. She raised up and I thought she was going to let me inside her pussy finally, but that was just horny wishful thinking. She wrapped her thighs around my dick and lowered herself down. It chafed but also felt sexy in a way.

"What are you doing?" I asked.

"Riding you," she said, "Without breaking the rules."

Well her thighs were touching my cock, but I supposed that wasn't really "touching my cock" any more than when it had poked against her pubic mound. It's not like she was using her hands, mouth or her glorious pussy. Her thighs felt pretty good though, in my level of horniness. She pressed them together and raised herself up and down on my cock, all the while grinding her clit against me when she lowered herself down.

I just liked that I'd made her so horny she'd invented this goofy style of sex-but-not-sex to get us off without breaking the rules. She fucked me with her thighs and it felt so warm and loving. My own sister was having sex me... well, close enough for tonight. What I liked best was that she was so aware of it and even initiating things, she was kind of the opposite of Aunt Olivia.

I played with her tits and kissed her on the lips as she squeezed my cock with her thighs.

"Am I your girlfriend?" she said, breaking the kiss.

"Y-yeah," I agreed in confusion. Why not, though? I loved Christie and having my sister as my girlfriend seemed incredible. Maybe it would even lead to her to agreeing to break the rules about what kind of contact we could have.

She squeezed my cock with her thighs as she lowered herself down, grinding her clit against my crotch. This was a woman who knew what she wanted.

"I love you, Christie," I said softly, a contrast to how overly loud we'd been for the girlfriend thing. Even Aunt Olivia had her limits of obliviousness, I didn't want her to hear us through the wall.

"I love you," My sister said, bucking up and down on my cock with her thighs fast. I could see her tits jiggling wildly as she rode me. It was too much, I shot my cum, feeling the ropes jet out with intense pleasure, no doubt landing on my sister's back and butt. She squeezed my cock and rubbed her clit against me one last time then was moaning in a passionate orgasm, kissing me on the lips as she came.

"What was that?" she said.

I heard footsteps and faint noise above. Maybe hip hop music playing on a stereo. The walls were thick here but not 100% noise-proof.

"Probably some college students partying in the condo upstairs," I said, not thinking much of it.

She sighed contentedly and cuddled up with me under the sheets.

"I love you, Mark," she said softly, "And Aunt Olivia too."

"Yeah, I love you and Aunt Olivia too..." I said, feeling like the luckiest man alive as I fell asleep with my sister in my arms, and Aunt Olivia just down the hall.