Backing Up

"Ah," she grinned. "Good! Very good! You are weak! Very weak! I will wreak my pleasure upon you!"

I struggled half-heartedly, but to be honest I was loving her show of superior strength. Besides, I could feel myself right on the edge of orgasm, and her vagina was deliciously tight around my dick.

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We had met innocently enough. My ship had come in to this backwater port a few nights before and my shore leave was finally due. In some ways I didn't mind being one of the last off the ship. Sure, the rest of the crew would have sampled the local delights already, but that just meant I was better informed.

They said the place was a shithole, by the way. There weren't even any whores, apparently, and the women wouldn't look at you for love nor money. That's what most of them said. There were one or two who were normally boisterous who came back... quieter.

I've never been a fan of paying for it, myself, so that didn't bother me overly. I have an active fantasy life and I didn't have any particular needs or expectations. I was just out to unwind, put some distance between me and some of my more excessively red-blooded crewmates, and maybe get into a little trouble. Nothing too demanding.

I couldn't help myself, though. In a bar full of locals, she was beautiful and alone. It didn't look to me as if standards of beauty were so much different here, so I couldn't figure out why, and curiosity got the better of me.

"May I join you?" I asked, as politely as I knew how.

"If you must." Her head hung. She was nursing a tall drink.

"I'm sorry for being so forward, but I was wondering how such a beautiful lady could be spending the evening alone?" I said.

She looked up at that, her brown eyes fierce. "Hah. You are an outsider. You do not know. I am weak, therefore they shun me."

I took a closer look. Her biceps bulged. Her tank-top fit her like a glove. A fine sheen of sweat gave her an attractive shine. I guessed her height as at least six inches greater than my own, her shoulders broader than any other woman in the place, and most of the men. She was a dreamy amazon queen.

"Weak...?" I mumbled, weakly, trying not to stare too hard at her thick neck.

She made a fist and thumped it slowly on the table. "They tell me I am over-compensating. But I am the weakest of my clan."

My mind's eye tried to picture a host of women even bigger and more powerful than her, and it had trouble. My dick got hard, which did not go unnoticed.

She peered down, a wry smile now turning her lip up at the corner. "So I am forced to bed outsiders. Even then, sometimes I am not strong enough."

One thing then led to another, until...

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Just as I could feel my cum rising, and my prostate ready to go into those beautiful contractions, her muscular vagina clamped down hard at the root of my cock. I'd never felt anything like it. I mewled and twisted, but she had me pinned so easily, she was stronger and heavier than me by a long way.

I had been loving that part, until now. Now I was feeling a little bit trapped.

"Hah-ha, yes! Yes!" she cried, her satisfaction giving way to ecstasy.

I started to feel something very peculiar. Her vagina had formed a tight seal around my dick. I was worried that a rather splendid orgasm was about to get ruined. But then the pressure started to increase. My dick felt like it was getting crushed by her. My arms and legs felt weak and floppy, my stomach was in knots. Then I felt her spasming, and things got even worse.

Have you ever taken a piss? Sure you have. It usually feels pretty good, right? And sometimes, when you're half-hard, it can feel even better, even though it takes a good while longer?

Well, now imagine the piss getting forced back up your hard dick. Except, it's not piss, it's amazon-woman cum-squirt, and it's heading back up your pipes, and you don't know what's going to happen next.

My dick clenched hard in the slick fist of her vagina, I panicked and tried to work my pelvic floor to restart my own orgasm.

"Haaaaaah," she exhaled. "So you do have some fight in you!" Her piercing eyes bore down on me and she opened her mouth wide. It was a little scary, she was a big girl with perfect teeth. I was unprepared when she clamped her mouth on my neck and started to give me a monster hickey. I lost what little resistance I had when she found the right vein and teased it with her teeth and tongue.

She wriggled a little from side to side, yanking my cock painfully around with her, and I felt the backflow sliding past the root of my dick.

The thing is, it didn't feel bad. Uncomfortable, sure, but my pleasure centers were firing on all cylinders. I caved, went limp in her arms, and she released my neck and screamed in victory. I felt her vagina spasm again and again, pumping her sticky fluid into me, and I... I think I liked it.

Everything was great until it reached my balls. These things are not designed to work two ways. Luckily I think I lost consciousness at that point.

-------

The women of Port Lesbos Station do not measure strength in terms of ordinary muscular capacity, but in terms of the maximum sustained backpressure they can apply with their vaginal ejaculate. While much of this is determined by genetics, it also requires excellent control over the pelvic floor muscles and the additional sphincter muscle that I had felt clamp at the root of my cock. It must be tight enough to form an external seal, but not so tight as to put a crimp in the urethra.

This is the kind of evolutionary strategy that sometimes crops up in isolated communities. It selects for higher pressure prostates (in the men) and powerful vaginal muscles (in the women), not to mention ever-more voluminous ejaculate (in both). Insemination is a battle, and many partners may be tested before one is found to overcome a woman's resistance. And naturally, such a strategy itself prohibits outsider genes from mixing with the locals; us poor foreigners just aren't equipped.

Of course, in modern spacefaring times, things were different, and love played a part in the equation too. It wasn't obligatory to battle as we had battled, although it was one recognised way to have 'good' sex, if 'good' is defined by what happens in the movies.

And then there was the taboo of full reversal. That was when a woman was so much 'stronger' than the man that she could force her ejaculate all the way back to his balls, rendering not just his sperm useless (for a few days), but also busting his balls from the inside. It was... not fun. For the man. For a certain type of woman, ones with a sadistic streak who revelled in dominance...

I mean, how was I to know it was a fetish bar?

She's educated me, since then. They still look at us snootily, sometimes, the women she says are so much 'stronger' than her, even though she could break them in half without breaking a sweat. But they respect her now, if only grudgingly.

After all, I am an outsider. Easy meat, when the meat doesn't know what's coming.

Now I know. We're going on a date tonight. I'm going to drink a lot of water, and see if I can't put up a better fight...

...I think I'll probably still lose, though. My girlfriend is so strong.