Me and Nathan

I'm 18 years old, and there's no secret to anyone, really, that I'm a slut. Actually, most people in my life even know that I'm willing to take money for sex, and quite a few of them take advantage of that. Not that I mind.

This story is about me and Nathan, who is actually my sister's boyfriend. He's a couple of years older than us, and I know he likes to be with my sister because he likes the challenge. We're identical twins, both blonde, both slim, both very pretty, if I do say so myself. Sarah has bigger boobs than me, though, which is so not fair, and she's also a bit taller, all of this because I got very sick when we were little, and it stunted my growth.

Anyway. Sarah is also somehow still a prude. She almost never wears skirts or blouses, but pants and sweaters, and she almost never wears makeup or anything, and I know that she is notoriously difficult to get into bed, even for Nathan. But he's bossy, and he knows what he wants, and he also knows that once he's gotten her naked and horny, she lets him do anything.

But sometimes, I know he gets bored. He wants her to take a more active role, not just struggling and then giving up, but maybe seducing him every once in a while.

Luckily, there's me.

He knows how to tell the difference between us, obviously, like I said it's not difficult, and so I've never pretended to be Sarah. But a couple of weeks ago, I went over to their place, mostly because I was bored, and they live in the same building as me. Sarah was in school, but Nathan was home, watching TV and having pizza. He let me in, and I think he knew at once what I wanted. I was wearing a short, ruffled skirt, and a blouse that showed my cleavage. Now, I said Sarah has bigger boobs than me, which is true, but that doesn't mean that mine are small. They are certainly enough to turn heads, if I want them too. Especially now, being 5 months pregnant, and still breastfeeding my daughter, they are swelling and can almost match my sister's.

"Sarah should be home within half an hour," Nathan pointed out as I closed the door.

"Do you mind?" I asked, smiling.

He grinned. "Guess not."

So he let me into the living room, which was neat as always, except for the pizza box and two cans of coke he had thrown on the floor. He was a slob, Sarah was the neat one. On the TV was hockey, sound turned down.

"So," he said, throwing himself down on the couch. "What's up?"

He smiled and glanced at his crotch. He was wearing slacks, and I could tell he knew what was coming.

"Not much, it seems," I answered, teasingly.

He smirked. "Well, I guess you'll have to do something about that."

I walked over, swaying my hips, and went down on my knees in front of him, stroking my fingers along his thigh. "Oh, you'd like that, wouldn't you?"

He took a deep, shivering breath. "I would, yeah."

I moved closer, almost letting his crotch touch my belly. He looked hungrily at my bump. No one knows for sure who the father is, and I've been letting every guy I was with around the end of January believe that it might be them. It turns most of them on. Including Nathan.

I let my fingers move from his thigh to his crotch, softly squeezing and he moaned. I smiled, and bent down to kiss his crotch, pants still on.

"Oh, come on," he moaned, his fingers grabbing my hair. "Just ..."

I hushed him. I was in no hurry.

I nibbled his pants, then brought my hands up to pull them off. He willingly let me, and his cock, rapidly going from half hard to proper wood, sprung out at me. I smiled, and kissed the tip of it.

"Tell me what you want," I said.

"You," he answered.

I shook my head. "Not good enough."

He groaned. "I want you to suck my dick, Lo."

I grinned, and eagerly took his cock in my mouth.

He gasped, and once again his hand found the back of my head, trying to push me down further. I resisted, only slowly letting my tongue play around the tip, the shaft, and going further down at my own pace. He moaned again, thrusting his pelvis forward, and then I let his cock slide all the way down into my throat. I let him set the pace now. Hard and deep, I swallowed him deep, listening to his moans and feeling my pussy get wet. My heart beat faster, and I had to force myself to struggle free from his grip before he cummed. I crawled up on the couch with him, and positioned myself so my pussy was right over his cock. I wore no panties. Then I met his eye.

"What do you want?" I asked, my voice breathy.

"I want you to ride me, Lo," he answered, putting his hands on my hips. "I want you to ride my cock like the fucking whore you are!"

With that he showed me down, and penetrated me hard and fast. I moaned loudly, tossing my head back and just enjoyed the feeling of his cock filling me up. I hadn't had anything but my fingers in my pussy all day, and I had missed this feeling.

Nathan moved his hips as I rode him, trying to push himself further and further into me for every thrust. I willingly let him, enjoying the feeling of his cock inside me, rubbing against the inside of my pussy, hitting just the right spots as I guided him towards them. I allowed myself to moan loudly, to match his groans, as I let his shaft move in and out of me.

I got lost in the feeling, until Nathan suddenly moved, and I ended up on my back in the couch, with him on top of me.

"You are such a fucking whore!" he said, panting as he fucked me hard.

"Yes!" I answered. "Ah, Nathan, take me!"

He slapped me in the face. "What do you say, whore?!" he demanded.

"Please!" I called, the stinging of my cheek almost lost in the pounding of my pussy. "Please, Nathan, cum in me!"

"I'm gonna cum in you, whore!" he groaned, pushing harder and harder. "I'm cuming!"

"Ah, yes, please! Please, cum in me!" I could think of nothing except the feeling of having my sister's boyfriend pounding me, of having him spill his seed in me, I wanted it so bad, my pussy tightened around him, trying to squeeze it out of him.

He called out as he cummed, then he slumped on top of me, breathing heavily, and I relaxed, enjoying his weight, which he at least had the sense to shift more to my chest than the bump in my belly, and the smell of sex. I hadn't cummed. Not that it mattered, sex to me isn't about cumming. Not that I don't enjoy it when it happens, but I far more enjoy the sensation of giving so much pleasure to another person.

I lay still there for a while, then opened my eyes and glanced at the doorway, and saw that I was right. Sarah was standing there, arms crossed over her chest, looking hurt, almost as if she had never walked in on a similar scene before. We hadn't heard the door open.