The Sister, Part Thirteen [M19/F18] [Cheating] [Erotic Couplings]

**PART THIRTEEN**

Natalie stood there, content and confident in her topless state. I couldn’t take my eyes off of her, and she knew it. Her pink bikini bottoms made it so she was more or less just wearing underwear. Other than that, however, every inch of her was on display. The girl was a perfect combination of cute and hot, and it was obvious now that her youthful innocence was just a mask. In the bedroom, she was bratty at worst. At best? A fucking seductress.

“Look, Natalie . . . ” I began. Forcing my gaze upwards and away from her bare breasts, I found myself at a total loss for words. Because as badly as I wanted to insist that this was a gigantic mistake, Natalie was still offering herself up for me. And now that I had a taste of how good she was in comparison to my girlfriend, as well as the visual temptation before me, my faithfulness was continuing to waver. Could I still use the ‘turned on’ excuse after my recent release?

She just smirked. “Yes?”

No. This was a terrible idea. “Please get out. And swear that this stays between us.” I just needed her gone so I could sort all this out. Jessica and I were perfect for each other. Natalie was literally just sex appeal, as it’s not like I knew anything about her apart from the bits and pieces I heard from Jessica talking about her family here and there. Even if Natalie was better in the bedroom, which was very likely considering the talents she had already shown me, that wasn’t enough of a reason to risk blowing up my relationship. I quickly pulled my underwear up to cover myself, belatedly realizing that trying to push Natalie away while my pants were halfway down my legs wouldn’t be the strongest move.

She took a deep breath, followed by a dramatic sigh. It was enough to make her chest rise and fall, which could have been intentional. The motion was noticeable enough from a few feet away that my eyes were drawn back down for a split second before I focused above her neck again. “Kicking me out? Rude.”

“I’m serious, Natalie. You can’t tell anyone.”

“Don’t worry; I don’t kiss and tell. Or, in your case, suck and tell,” she winked, “So, when are we fucking? And where? Ooh, I’ve never done it on the boat before!”

“No, we’re not-” I cut myself off. Saying it out loud felt like a bad idea. Like Jessica could overhear this conversation at any given moment, even if I had no control over what her sister was saying. “We’re not doing that.” Speaking of my girlfriend, it wouldn’t be long before she started wondering what was taking the two of us so long. And, now that Natalie had gone down on me, I was left in a position where I’d have to play it cool and pretend that nothing had happened apart from dawdling. Not to mention that this was already a secret I’d have to take to the grave in our relationship, which was one of the many worries I had before; the last thing I needed was to do *more* with Natalie.

She gave me another one of those cute pouts. “You just said this stays between us. And it will. So, like, why won’t you fuck me?”

Unbelievable. “Why do you think?!” Was it not obvious?

“You *said* you wanted to,” Natalie reminded me. Taking a step forward and looking right into my eyes, she echoed my words from earlier. “I want to fuck my girlfriend’s little sister.” Another step. “And you meant it, didn’t you?” Sauntering over to me, just like she did downstairs, she gently took one of my hands and began lifting it while looking up at me with those ‘fuck me’ eyes.

There was nothing forceful about this latest advance. Or any of her advances, honestly. I was more than capable of pulling my hand out of her delicate grip, or taking a step back, or pretty much doing anything to stop whatever the eighteen year old vixen was instigating this time around. But I didn’t. All I could do while staring into those captivating eyes was say, “We shouldn’t . . . ” while letting her place my hand on one of her bare breasts.

“Hot, isn’t it?” Natalie smirked. She held my hand on her chest and guided my fingers into a small squeeze. “You want to fuck me, but you shouldn’t. And it would be such a shame if you didn’t. I’d bet you anything that I’m better in bed than my sister is.” Her other hand landed on the front of my boxers and she brought me back to my fullness with just a single touch through the thin fabric. “Plus I’m cuter.” She led my thumb to brush her nipple, taking a shaky breath from the sensation. Fuck. Apparently both sisters were sensitive to that motion.

That bit of knowledge was confusingly hot, as I reflexively began wondering what else their bodies might have in common. In a way, it was like having a cheat sheet, though I doubted all of the answers would be right. “Natalie, wait . . . ” I murmured. She was exactly right. I *did* want her, but that didn’t mean I should be acting on that desire. Easier said than done, when I was feeling her up for the first time and once again hard in her hand.

“If you want to stop, say the word.” Giving me the choice, yet making it impossible by punctuating the offer with a light squeeze below. How could I deny her? I had only just been given the opportunity to explore the chest I had been eyeing for what felt like ages, and her touch was magically teasing. And those fucking eyes . . .

I knew it was wrong. Just like before. But instead of voicing for the hundredth time that we shouldn’t be doing this, I simply gave a squeeze of my own to the soft breast I was palming.

Natalie just smirked again. “That’s what I thought.”

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NSFW: yes


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