Kouki is in control...

"Hold still and try and relax," I said to my lover.

"I don’t think I can go through with this," my nervous brother squirmed, but didn’t move away.

"Don’t be a baby. It’s almost in," I chided him and pushed just a little harder. Even covered in oil his virgin hole was a tight fit, but one last firm push finally did the trick. He groaned and clenched instead of listening to my advice and just relaxing and letting it happen, but I personally understood the natural reaction.

With our sex play over the last year, it was inevitable that we’d both want to have sex with our lovely shared bride at the same time, so we’d both had turns being the one to fuck Chizu’s ass as well as her pussy. She loved getting double stuffed, so of course, I felt it was only fair to have my brother fuck my ass at least once to see how it felt from the other end.

Surprisingly I really liked it, though it was uncomfortable it also really turned me on and now sometimes I asked for it instead of in my pussy. Kenji wasn’t that into it, so I didn’t ask often and he had two horny mouths and pussies that already loved being filled, so it really wasn’t a big issue until Chizu’s pregnancy became an impediment to our lovemaking. Sometimes she just was bloated and sore, and she did swell up like a blimp, almost doubling in weight. We didn’t really know who was the father, but publicly of course she was Kenji’s bride and I was just his prudish sister that refused to date anyone else after the war ended and all the men came home. Chizu became like a true sister to me, though I still enjoyed plowing her pussy like a man more than I would have ever dreamed possible.

But now with her out of the sex equation, while her body healed from the very close call she had with the birth of her first child, a big and healthy nine-pound girl, Kenji had lost the bet we had so I was claiming my forfeit: the chance to fuck his ass for a change. He had been very uncomfortable around my new penis early on, but had grown to show it as much affection as my other private parts, rubbing, even kissing it a little, though I knew asking him for a blowjob would cross the line his manhood just couldn't accept… yet. At least Chizu never refused me that wonderful pleasure as she also got to finger my pussy at the same time. She really turned me to goo as she made me her screaming meat puppet with her tiny mouth and fingers causing my whole perverted body to orgasm, inside and out, simultaneously.

I looked down at the boy's ass I now impaled and held still, letting his virgin asshole adjust to being stretched open with my swollen girth. I tried to be patient as I already knew everything he was going through, but I was just so excited. I pushed in a little more and he cried out, "Stop! No more."

I sympathized, but I was through waiting. I hadn’t gotten a good fuck out of my dick in weeks other than by jerking off while Kenji fucked my pussy. Now I even masturbated alone frequently if no one was around, something I'd only done sparingly before we all this, more for experimentation than anything else. But since I grew a cock I sometimes found the uncontrollable urge to rub myself several times a day. I couldn’t help, but count the minutes until I was with Chizu again to let out another load of spunk in her warm mouth, steamy twat, or unbelievably tight ass! I knew how good it felt from experience, but until she was feeling better I was going to take out my lust on my big brother. Pushing in deeper into my cry-baby brother, I slid in his rectum until I could feel the full length of my prick up his bum.

"Oh, brother, you’re so tight for me," I gasped as I finally bottomed out. He was actually crying real tears now, but I knew he’d learn to like it as I had. Since I’d yet to conceive with all the loads he’d put inside my own womb I was worried that the price I paid for being able to feel the pleasures of a man had robbed me of the ability of ever being a mother. It saddened me more often than I’d ever admitted to anyone, which is why I secretly hoped that Chizu’s baby was mine. Kenji was a wonderful lover when it came to my girl parts, and I loved feeling him pump his salty sperm deep inside every one of my hungry holes, but now I never quite came as hard as I did when it was out through my new penis.

I paused to let him catch his breath for another moment before I couldn’t resist waiting anymore. Slowly, yet with determination, I began easing back and forth as I prodded inside his rear end with my manhood. "Please tell me you love it," I gasped enjoying the amazing sensations his bowels were giving me.

"I love it," he whispered through gritted teeth, yet I thought I could hear in his muted voice the truth that while he was mostly humoring me, a small part of him actually did. Then I felt my balls oddly slap back against my pussy. His balls were bouncing against mine as he had taken hold of his own cock to begin jerking off while I buggered him, just like I always did. I glanced down and saw him jerking his rock hard cock and that gave me the signal that now it was time to get on some serious fucking!

With that knowledge, I took him, more roughly, though still much slower than I truly wanted, but this was still his first time. He'd bleed and be sore, but I also knew for a fact this would not be the last time, bet or no.