Mark

Well, I couldn't let my sister fuck another guy. She was pretty much my girlfriend at this point, along with my aunt... okay this all sounds like a redneck joke, but even if it was trashy, she was my girlfriend and mine alone. I'd do whatever it took to make sure I was the only guy who ever made love to her.

If Lacey was giving us the choice, well, I'd be the one to fuck Zach. I suppose I'd always been a little curious about guys, I don't think I'm really bi, but this situation was unique. She'd said one of us had to fuck Zach and I knew exactly how I'd do that. If I'd had to take him up my ass, well, no way in hell. But me giving it to a guy for my own pleasure was a lot different... that was the way I'd want to do this.

"Okay," I said, "If one of us has to fuck Zach then obviously it will be me. You don't want to do him do you Christie?"

"No way," my sister said convincingly, "But Mark..."

"Don't worry, I promise I won't turn gay," I said.

Christie giggled. "You'd better not. Or even bi. I'll let you do it this once... but if you start hooking up with dudes on Grindr when you get back to the city..."

"Not gonna happen," I said squarely, and she seemed convinced.

The other brother/sister pair were also discussing the logistics of this.

"You want me to let him fuck me, Mistress? You want me to take Mark up my ass?" Zach said. To my surprise he didn't sound disgusted or humiliated. He sounded... horny.

"Yes, ****," Lacey said to her brother, "Take your cousin's cock up your ass for your mistress."

Zach smiled and went to Lacey's purse. "May I use lube, mistress?" he asked.

Lacey shrugged. "I suppose," she said, "Mark's cock isn't that big but it's just barely big enough to hurt you, I guess."

I rolled my eyes but figured this kind of **** was just par for the course in their relationship. Zach went into Lacey's purse and got out a container of love. My sister and I smirked openly. Zach bent over, presenting his ass to me and spread the clear lube on his utterly hairless butthole. This metrosexual waxes his ass! But that seemed about right for a pretty boy from New York City.

"Get me hard," I said to my sister, "Obviously I'm gonna need assistance this one time."

Christie giggled and dropped to her knees, laid out submissively before me in a much more pleasing way than Zach. I pushed my soft cock into my sister's mouth and she started to suck me eagerly. Having my sister suck me in front of Lacey and Zach was hot, it felt like showing off how wonderful Christie was, what a great girlfriend I had. This was hot. This was actually the first blowjob she'd given me, I suddenly realized. Perhaps she made an exception to her "anti-**** rules" so she didn't have to fuck Zach, or maybe using her mouth on me didn't count as touching anymore in her wacky logic. Or maybe she just wanted to suck my dick. I didn't argue.

Her mouth felt so good. She'd never socked a dick before but it came easily enough with her enthusiasm for me. She took about half my length, curiously feeling a cocck in her mouth for the first time. This was more than enough to get me hard. Her virgin mouth felt so delightful as she rolled her tongue over my shaft and explored her brother's penis with her mouth.

"You guys are cute," Lacey said. Maybe she meant it as a tease but my sister blushed and I took it as a complement.

I pulled out of my sister's mouth fully hard.

"Well let's get this over with," I said. I got behind Zach, who was leaned over onto the bed, presenting his ass. Maybe it was because he was so clean, or because my sister had just acted as my fluffer, but I was horny and ready to fuck, even though it was my male cousin. Besides, I had to do it, so why not at least enjoy it?

Christie stood naked in front of me and mouthed "Fuck him". She knew the alternative was her fucking him and was clearly appreciative that I was doing this for her.

I slid my cock into my cousin's ass slowly, not knowing what to expect. It was surprisingly tight and only once I was inside did I worry about fucking a guy without a condom.

"He hasn't fucked other dudes... yet," Lacey teased, "I think I'll start him soon. But so far I've just fucked him with strap-ons."

Well that was an interesting thought, my big-titted cousin fucking her athletic brother with a strap-on dildo. But it was more of an amusing idea than something I thought I wanted to see in person, much less re-create myself.

Reassured, I pushed my cock deep into my cousin. The lube meant I slid in easily despite some tightness. It felt alright, but I was looking at the sexy ladies to keep myself turned on, and found myself imagining I was fucking their asses, not Zach's. Still, there was a certain appeal to fucking a very submissive dude's ass. He was such a wuss and he was acting like a total chick, moaning as I rammed my cock up his ass.

Still, he was a guy. His cock flopped under us, his ass felt different than a woman's. Deeper, not as tight... but there was a certain appeal. Like messing around with a boy out of curiosity, I guess. I started to feel pretty good as I buried my cock in his ass, and it helped that my naked sister was cheering me on and watching the gay sex with fascination, her face a foot from my cock pistoning in and out of my cousin's tight ass.

Since Zach could obviously take an ass-fucking I didn't hold back, enjoying myself as I rammed him hard. He groaned and asked his sister if he could jerk off, and she teased him but agreed.

Even though I was fucking his ass so hard I was sure I'd have come if he was a lady, I wasn't anywhere close. Funny how that works. But if we were asking for favors, I said, "Christie, I need some help. Give me those nipples."

Christie grinned and offered me her tits casually. I sucked on my sisters tits eagerly and this made it easier to forget I was fucking a guy. I imagined it was Christie's ass and pretty soon I was getting close. I banged against Zach, finally enjoying fucking my cousin's ass. Just took a little help from my sister.

I started to cum and pulled out, shooting my sperm mostly over Zach's back. I moaned as I came and Zach was absolutely squealing as he jerked himself off to an orgasm the sensation of my hot cum landing on his back.

After that there was a lot of noise in the hallway and we understandably got a bit nervous about getting caught having gay sex at a teenage party in a very red county. It had felt good to fuck Zach's ass, but I was pretty sure I'd never do that again. My sister and Aunt were plenty.

As we were getting dressed, Lacey and my sister were comparing bras for some reason. I guess they both need extra support. Zach said to me quietly, "Hey dude you're not gonna tell anyone are you?"

I shrugged. "Believe me I don't want anyone to ever know about this, dude."

He accepted that and we all finished getting dressed. Christie was by my side the whole night and Zach couldn't even look at me, not that I wanted him to.

"Are you okay?" my sister said as we sat on a couch in the luxurious basement, teenagers dancing and flirting all around us.

"Sure," I said, "I'll never do that again, but it wasn't too bad."

"Thanks," she said, "If I'd had to fuck him..."

"He probably wouldn't have been able to cum anyway," I teased, not letting her finish that thought, which probably would have ended with me not being able to forgive her for fucking another man. Sad, but true.

"Hey I could make a homo come!" she said with a laugh, "Besides he's bi. He's obviously into his sister."

"That makes two of us," I said with a grin. If we hadn't been around people who knew we were brother and sister, I would have made out with her right there on the couch. "But I'm glad you didn't fuck him. I'm gonna be the only guy you ever fuck, right?"

She blushed and looked down. Actual sex was the last boundary we had left between hardcore ****. For a moment I thought I'd gone too far, but then I heard my sister's lovely voice over the country music, "Yes, Mark. You'll be the only one."

Don't worry, there are other versions of this chapter coming soon, including the one I think the vast majority of my readers will actually like. I was just taking advantage of the ability to do alternate versions of a story here, something I'm usually too lazy to do.