Because We're Bad

She raised herself just enough that she could pull my underwear back and let my erection spring free. Her eyes gleamed as she saw it again and she crawled backward a little so she could lean closer.

"Mmm, I've been waiting to see you again," she said, addressing my cock rather than me.

Her fingers encircled my shaft and stroked it lightly, sending a shiver through my body. It was becoming more and more real to me with each passing second, the idea that we were actually going to have sex. It seemed so weird when I thought about it. When I focused on my sister and the way she was making me feel however, I couldn't imagine trying to stop it.

I sat partway up in an attempt to get at Kristin's pants again and was quickly pushed back down. She waved a finger in my face like I was a misbehaving puppy.

"Ah ah, stay right there," she said. "I don't want you going anywhere."

"Wasn't going anywhere, just trying to help," I said.

"Well be a little more patient, you're usually better than me at that aren't you?"

"That's because most of the time there isn't anything worth getting excited over. This isn't exactly a typical situation for me."

"No, I guess it isn't."

Perhaps to placate me a little, Kristin stood up on the bed with her feet planted on either side of my waist and tugged at her pants slightly. She turned around before pulling them down too far so that her panty-covered butt came into view first.

"That better?" she asked, wiggling her butt at me and letting her pants slide down her legs.

"Yeah, I gotta say you look good in just your panties," I said.

She rolled her eyes at me over her shoulder but began swaying gently as she stepped out of her pant legs, clearly not minding too much. Her fingers hooked themselves into the sides of her panties as she turned around, threatening to pull them down as well.

"So how do you think I'd look in nothing at all?" she asked.

"I don't know, maybe you'll have to show me so I can decide."

Kristin smiled and the front of her panties came down a little, just barely keeping her pussy covered. She continued dancing in slow, deliberate movements above me making it harder and harder for me to stay put like she wanted.

"You know I'm not above tackling you to the bed if I really have to," I said.

She giggled and lowered herself until she was nearly sitting on my stomach.

"Maybe you would, but we both know you're completely incapable of holding me down if I don't want you to." She leaned in closer so her lips were almost touching mine. "Right now though, I might let you if you tried."

I closed my eyes as she kissed me, but simultaneously circled my hands around behind her and down her back until I felt the top of her underwear. Her butt brushed against the tip of my cock as she moved back and forth slightly, reinforcing my need to be inside her. Those panties had to go. I grabbed the material firmly in both hands just above one of her legs and pulled.

For a second I thought nothing was going to happen, then there was a satisfying ripping sound and my sister's panties hung limply from their still-intact side. Kristin gave me a look of shock that quickly turned into an appreciative smile.

"Did you just rip my panties off?" she asked. "I didn't think you had it in you. There must be a bad boy in there somewhere after all."

"What can I say, you bring out the best in me," I replied distractedly.

The front of Kristin's panties had fallen away leaving her pussy naked in front of me for the first time. After feeling it only the day before I had a decent idea what to expect and I was in no way disappointed. It was just as smooth and perfect as I could have imagined and my first instinct was to reach out and touch it.

Kristin made a small sound of approval as my fingers ran over her pussy lips. Her arousal was readily apparent and it didn't take long for her hips to start rocking against my hand. However much teasing she'd planned on putting me through, her need was clearly comparable to mine and I didn't expect her to try holding out much longer.

As I guessed after a minute or two my sister reluctantly backed away from my fingers and moved herself over my cock. She made sure to grind up and down the shaft a couple times to spread her wetness along it and make the next part a little easier.

Soon Kristin was ready and we made direct eye contact as she positioned the entrance of her pussy at the tip of my waiting erection. Nothing needed to be said, we knew what we were doing and there really was no way either of us was going to back down now. I put my hands on her hips and gave a little downward pressure, just enough to encourage her. Then, as she let gravity take over, her pussy lips parted on either side of my cock and allowed me inside my sister.

For a long moment I was only aware of the sensation of Kristin working me deeper inside her, the rest of the world may as well have disappeared for all I would have known. A big part of it was simply that I was having sex which tends to occupy my attention all on its own, but there was also that voice in the back of my mind telling me that she was my sister. Strangely it wasn't a guilty thought so much as an acknowledgement of what was happening. It was like my conscience had given up on morality and just wanted to point out an interesting fact.

"Ooh, this feels way too good," Kristin breathed, breaking the silence. "How the fuck did we not do this before?"

"I think it had something to do with being siblings," I said.

"Smartass. You know what I mean."

"Yeah, I do. But I don't even really know how we ended up here as it is."

"Maybe 'cause we're both kinda bad even if you pretend like you're not."

"You might be right."

Whatever the case was it didn't really matter to me at that point. I had my sister on top of me riding my cock while I ran my hands freely over her almost-naked body; it wasn't the best time for deep introspection.

Kristin leaned closer to me as she braced herself on her arms, putting her chest within much easier reach. I took the opportunity to lift my head and suck one of her nipples into my mouth as I caressed her other breast with my hand.

Seemingly in response to my actions Kristin increased her pace, rocking back and forth on me like a girl possessed. Unfortunately her movement pulled her breast from my mouth and I didn't want to risk hurting her by trying to keep it still. Instead I lay back and just watched her as I let my hands settle on her ass. She was breathing harder from the exertion but still grinned as she caught me staring at her swaying breasts and bent down for a quick kiss.

"It's nice not having to just imagine anymore isn't it," she said.

"Yeah, but it's going to be hard not to think about sex around you now. It could make things a little awkward."

"As if you don't think about sex all the time anyway," she teased.

I didn't bother arguing the point even if it was bit of an over-generalization. I could sense the changes in my sister's body as she somehow fucked me even more frantically than before and I guessed she was probably getting close to orgasm. I wasn't that far behind either.

Within moments Kristin threw her head back and arched her whole body while her hips continued pumping me almost of their own volition. Whether purposefully or not she didn't make too much noise even though her mouth opened in nearly a perfect a circle and she looked as though she might scream.

I think it was that appearance of pure sexual ecstasy that really did it for me and I came even as that image of my sister burned itself permanently into my mind. Again there was that inner voice reminding me just who it was that I was shooting my cum into, and once again I didn't give a fuck. There was nothing in the world my own mind could do that would make me regret what had just happened.

After another minute or so of gradually slowing down Kristin collapsed on top of me, moving just enough to let my softening cock slip out of her before lying still. I gently stroked her hair with one hand and pushed some of it back out of her face where it had fallen. She twisted her body strangely for a second, making me think something was wrong, but then straightened out and tossed the remains of her panties on the floor.

"I liked that pair you know," she said, not sounding the least bit upset.

"Sorry," I said.

"S'okay. Maybe we can go shopping for some new ones together."

Kristin grinned at the thought and, despite myself, I smiled too. I didn't know what she had in store for me, but it would certainly be interesting finding out.