Her Sister's Keeper 3

I shoved my ass back and quivered to feel it going into my hole as best it could. I felt my sphincter expanding, did my best to relax and let it in further. Lubricant chilled my walls as it was smeared off the dildo and into my flesh, it was comforting to feel the slickness of it. Maybe it would let the strap-on into my ass without totally devastating me. I was more open than ever, taking more than I'd ever imagined my sex life would involve.

I shut my eyes tight against the pain flashing through my stretched tissue, but the pain was overtaken by a flaring bloom of delight. Kate Bishop’s dildo was going even deeper. I was actually taking it into my ass, my bowels, everywhere in my body that wasn't meant to accommodate being infiltrated this way.

It was only a quarter of an inch, but it felt like my asshole was no longer my own. And I was only beginning to open, only starting to take what was going into me. I felt ecstasy flowing through the continuous pain of impalement like water through a dam; it was like coming without coming. I pushed back and gritted my teeth on the pain I was suffering to get off.

Kate Bishop then took her dildo by the base and pushed it in all directions against my walls. I let out a hiss as I felt the dildo prod one set of nerves and then another. I screamed as it worked deeper in with the rotation.

Shit. I was being fucked. I was actually being fucked in my ass, a dildo piercing into me, Kate Bishop enjoying being able to do this to me. She had to be enjoying it… that was the only way she could inflict this pain. Did she know how much I was enjoying it too? Or was she only taking Natasha’s word for it? I didn't feel like I had nearly the reserve not to show what I was feeling, no matter how embarrassing it was to get off on this debasement.

Kate Bishop panted harshly. Her breath came in short bursts, close to speech. On each exhale she seemed to mumble either my name or some curse.

I could've laughed. She sounded embarrassed… ashamed of what she was doing to me, or maybe how she felt about it. Not that I had room to talk with the delirious excitement I felt charging out of my filling passage.

I drove my hips back again and was rewarded with Kate Bishop thrusting at the same time, a short stroke that went right inside me, making me take whole inches at a time. I felt a frenzy in Kate Bishop like she was working towards something, on the verge of something. I turned my head as I met her driving strokes.

“Are you going to come, Kate Bishop? Is fucking my ass really enough to get you off?” I whispered over my shoulder, with what hushed voice my overwrought body could muster. “Because you're not even fucking me, Kate Bishop. You're just using a dildo on me. You're getting off on having a strap-on cock in my ass, you pervert, you like sodomizing other girls that much?”

I never would've expected it from such a nice, normal girl but she was. I couldn't believe it. She shook her head a little, but then gave up on denying it, hiding a grin like a little girl telling a joke and trying not to give away the punchline. Kate Bishop pumped faster and faster, losing all concern for my well-being as my ass proved able to take as much as she had to give it.

“Come! Come, Kate Bishop! Come from fucking my asshole! And make me come too! Make your bitch come with you!”

That did it. I felt the dildo buck and shake inside me, carrying the tremors that were going through Kate Bishop’s loins. My own climax shot through me as Kate Bishop fucked her own orgasm into my receptive body.

I was drooling, sweating, crying, wailing until I felt the leather harness chill my flushed skin and knew she was all the way in. Then I screamed.

I almost blacked out next. Kate Bishop was really fucking me now. She knew she could use my anus as her own personal fuck hole and she did nothing less. Her thighs slapped against my flesh each time she impaled me. I'd never known heaven could hurt so bad.

“Natasha!” I panted. “She’s fucking my asshole! Kate Bishop’s fucking me in the ass!”

I looked up into Natasha’s gorgeous face, only two feet in front of me. She was watching me, listening to me, and the thought that she’d heard and seen everything almost made me come. She wore a dazed look of arousal on her face, the voyeurism getting even to her. Her hand was down at her groin, rubbing between her legs with strokes that matched Kate Bishop. Then, seemingly helplessly, she groaned and started to speed up, a lustful smile covering her face.

“Bozhe moi,” Natasha muttered suddenly, coming back to herself with a shudder, replacing the open gratification on her face with her usual stoicism, leavened with a little amusement at herself. “You do make that look fun, Yelena. I’d almost ask ‘Kate Bishop’ if she’d mind helping me out next, but I know you, sis… no way you’ll want to stop for a couple hours, at least. So I’m just gonna go and see if I can find Wanda somewhere… maybe Pepper… or Maria.”

She walked to the door, opened it up—a thrill of panic flew through me at having myself and Kate Bishop revealed to the outside world, even if there was no one in the hallway at the moment.

“Toodles,” Natasha said, now with that familiar little smirk on her face, and she slipped through the door without closing it.

Siblings.

Kate Bishop kept stroking in and out of my ass… it felt so fucking good. My asshole was full of it, full of the lubricant it had carried in, letting it slip in and out with perfect ease. The sensation was delicious, but I still vibrated with anxiety over that open door that anyone could pass by and look into. Every moan I made no longer had a closed door to stop it; I tried to clench my teeth and grind down on any noise I made, but each time I had it locked down, Kate Bishop’s hips pumped behind me.

I turned my head over my shoulder and let out a gratified sigh at the sight of her body colliding with mine, fucking one little piece of orgasm into me at a time. “We have to shut the door, Kate Bishop… you have to stop… the door…!”

“I’m fucking your asshole,” Kate Bishop muttered, way past the point of caring whether anyone saw how much she was enjoying this. “I can’t believe it! Your whole fat ass is just… it’s around my cock! This cock!” She lanced it into me again. I squealed, taking so much at once, whole inches in less than a second… “I never did that! I mean, I—” Her words faltered.

“Shut the door!” I laughed, feeling high on what we were doing, giggly from the endorphins. And my flush of embarrassment wasn’t helping with the emotional overload frying my circuits. “You can fuck me all I want, just shut the door—!”

“Bitch!” Kate Bishop hissed, and I knew in a heartbeat exactly how she felt, a soulful connection in the middle of all this kinky raunch.

All she wanted was to keep fucking me, keep enjoying her new sex slave—what else could I be, at this point?—but I was ruining it for her. No matter how well-intentioned, because obviously doing this in private would benefit both of us and probably the New York heiress more than the anonymous, technically homeless spy—I was still being a not-very-good sub at the moment.

What I didn’t expect was how Kate Bishop would take advantage of my defiance instead of being her nice, normal self for one moment.

Her hand flashed down and struck me on my considerable ass. And it damn well felt considerable after it took that hit, every inch of it flaring with pain. Sending me slip-sliding back down the hill I’d climbed, getting over the pain of being sodomized to get to the pleasure. Now it hurt again. Now I was her bitch again, and not just her lover.

“What if I keep the door open, huh?” Kate Bishop said in a tone I’d never heard from her before. “What if I keep fucking you no matter who walks by? What if I keep fucking you even if someone takes out a phone and records us? If every single one of your fellow Widows sees how you like taking it up the ass? You’d still be my bitch. You’d tell all of them that Kate Bishop owns your ass and she’s the best fuck you’ve ever had. That you were coming over and over again with that big dick in your ass, because you’re a little anal bitch and every time you sit on that fat ass, you can’t wait until it’s full of cock again. Right!?”

“Yes!” I wept—literally. Tears swimming in my eyes and spilling down my cheeks. Blyat, it felt good to admit that.

Kate Bishop groaned and came out of me, relieving my ass of being impaled with a sort of plot. I literally sniffled at having her no longer in me. She stood up, swaying unsteadily, and I thought she would close the door, but instead she circled in front of me. Her strap-on swung in a low arc before my face.

“You want the door shut?” she whispered huskily. “Suck your ass off my cock. Suck it now.”

I didn’t hesitate, didn’t disobey. Maybe being a Black Widow for so long had made me a natural submissive—I just needed someone it felt good to obey. I wrapped my lips around the end of the dildo and instantly pushed my way down its length, ignoring or trying to ignore the indescribable taste…

And as I deep-throated what it was impossible not to think of as Kate Bishop’s erection, I brought my hands up to my breasts, rubbing them lovingly, pinching my rock-hard nipples. I could get off on this, I realized… though I really must’ve been an anal bitch, because I wanted to get off on being fucked in the ass more.

And I no longer cared about closing the door.