I knocked on the door to Beth's apartment for the first time in three weeks. I had been away for work and hadn't once stopped thinking about my sister since the night we had sex. The anticipation of finally seeing Beth again had me incredibly turned on. I could already feel my cock twitch in my jeans, and I was trying with all of my will to keep from sporting a hard-on outside of my sister's apartment. If we had any hope of keeping our relationship a secret, we were going to need to be discreet.

Her next-door neighbor already knew me since I helped her out with moving her boyfriend in last summer. Jane and Eric already knew that Beth was my sister, so popping a boner in the stairwell between the two units was going to be impossible to explain away if anyone were to see me.

Beth opened the door and threw her arms around me.

"Johnny! I've missed you so much," said Beth, dragging me into her apartment by the arm.

Thankfully, we've always been close. So, Beth being excited to see me wouldn't likely be seen as strange. After making sure the door had closed all the way, I drew her into a kiss and held her there for a moment before finally breaking away to tell her I missed her too. She hugged me again, this time for much longer than she had on the other side of the door.

"Is everything okay, babe?" I asked.

"Yeah, of course," she replied. "I just missed you a lot."

"I love you, Beth," I said. "Being away from you has been hell."

"Tell me about it. Masturbating isn't cutting it. I need you, Johnny," Beth replied.

Hearing her say she needed me lit a spark inside me. I needed to have her. I kissed her hard and pushed her back up against the wall. My tongue probing her mouth to find hers pushing back against mine. Her body was pressing hard against my pelvis as we dry-humped each other like a couple of horny teenagers. My cock was stiffening in my pants as she rubbed against it. I put my hands on her ass and pulled her closer into me. She had her arms around my shoulders already.

I then lifted her up onto me and she wrapped her legs around my hips. I squeezed her ass and worked her body up and down against my erection. I needed her- needed more of her. I stopped grinding against her long enough to carry her over to the couch, where I pulled off my t-shirt and kissed her some more.

"Fuck Johnny! I'm so incredibly wet right now," said Beth as she quickly unbuttoned her blouse.

"Mmm! I can't wait to taste it," I replied and smirked at her as I did so.

I reached my hands around her and unhooked her bra. I kissed her once more before moving down to her neck, kissing it for a moment, and then moving onto her breasts. I ran my tongue across her nipple, gently sucking her breast while she reached her hands down and started removing her pants.

"Oh, fuck Johnny! I want you to go down on me," she cried out as I suckled her breasts.

"With pleasure," I said, helping her remove her pants.

I moved my head down her body, planting small kisses on her as I moved towards her shaved mound. I could smell the aroma of her glistening cunt as I licked her clitoris. Her entire body bucked into me as I did. I started to suck and trace circles around her clit with my tongue, occasionally licking her slit, and probing the opening of her vagina with my tongue. She wasn't kidding about being super wet, and she tasted amazing. I couldn't get enough of her, as she squirmed and moaned. I felt her buck harder against my mouth, orgasm building to the point of no return.

"Johnny! I'm gonna cum! I'm cumming! I'm cumming," she yelled out.

I felt her body spasm and tasted the warm rush of fluid from her pussy as she reached orgasm. I slowed my pace and let her orgasm flow over her. Finally, after what felt like forever, I felt her body relax and I took the opportunity to clean her up with my mouth.

Afterwards, she sat herself up on the pillows and motioned to me that it was my turn. I mostly stood up with a knee still on the couch as she pulled me closer to her and lowered her mouth onto my penis which had softened a bit since our dry humping earlier. She wrapped her mouth around my cock and slowly started to bob up and down. One hand caressed my balls as her tongue tasted every inch of me. It felt like heaven. My sister had her mouth around my cock and just the thought of how forbidden this was, and how much I wanted it anyway, had me fully erect again.

She put her hands around my thighs, just below my ass, and pulled me deeper into her mouth. My sister had all seven inches of my erection in her mouth and moaned deeply against it. I was all but ready to cum as she did. I began to fuck my cock into her mouth and back into her throat as I felt the orgasm building in my balls. She was practically gagging on me as I reached climax, shooting ropes of cum into her throat while moaning her name loudly.

"Fuck Beth! You suck me so good, baby," I said, all but collapsing into her couch.

I steadied myself and sat down on the couch, rubbing my dick as she snuggled up against me and kissed me deeply.

"I love you, Johnny," said Beth.

"I love you too, babe," I replied.

I kissed her again and pulled her on top of me. She straddled me as I rubbed myself off, bringing my cock back to semi-erect. She rubbed her body against me as I put my hands around her ass. I kissed her as she rubbed her pussy against my penis. She was sopping wet already as I put my hand on my cock and started rubbing it against her clit and across her opening. Her wetness lubricating the head of my penis. She lowered herself onto me and let out a soft moan as I entered her. She was so wet that I slid all seven inches into her with ease, even as tight as she was. She kissed me deeply and started moving up and down. She was so tight, I probably wasn't going to last long, but I had to have her. I needed her, as she needed me. Three weeks might as well have been three years.

I could feel her pace quicken as she fucked me and grinded her clit against my pelvis. I grabbed her ass and started thrusting into her harder, faster. She moaned and rubbed her clit with her hand as I pounded her. My balls slapping loudly against her as I rammed my cock so deep it was likely hitting her cervix. I needed to cum, and I could feel she did too. Her breath was getting ragged, and she buried her head into my chest. She was moaning loudly.

"Oh, Johnny! Oh, fuck! I'm going to cum Johnny!" Beth yelled.

I could feel her tighten around my shaft. She was squeezing me tight, and I could feel myself reaching orgasm. Her body started to spasm. I could feel my balls start to twitch.

"Fuck Beth! I'm cumming too!" I cried out.

I pushed as far inside of her as I possibly could, and she reached orgasm as I did so. Her orgasm set mine off, and I climaxed deep inside of her. There was something so incredibly hot about filling my sister with my seed, as if I was marking her as my own. It felt like her body had been made to fit mine. My penis fit inside of her like a glove. She kissed me once more as my erection softened. I felt a glob of cum drip onto me as my deflating cock slipped out of her. We stayed there for what felt like forever. Cuddling, kissing, and living in our shared extasy.

"Johnny? We need to talk about us," said Beth, breaking the silence.

"What about, babe?" I asked.

"What about? How about everything, John. We're siblings! How the hell are we supposed to keep this quiet?" Beth half asked, half yelled.

"By not telling anyone? I love you, Beth! If I have to go to the grave with that secret, I will. I love you and I love having sex with you. We can't go back now. It's too late," I told her.

"We don't have to tell anyone for them to already know, John. Jane across the hall keeps acting strangely around me ever since the first night we had sex. I think she knows. God knows, we were both loud enough," said Beth.

"Shit. Maybe we can tell her it was a movie she was hearing?" I asked, knowing that would never actually work.

"Doubt it," replied Beth.

I wrapped my arms around her, hugged her, and planted a kiss on her head.

"We'll figure it out. I'm not ready to lose this. I love you," I told her, and adding, "I want to spend the rest of my life with you."

Beth smiled, even if she wasn't convinced that we would figure it out. She leaned in to kiss me, probing my mouth with her tongue. I found hers with mine and we made out on her couch, naked, for what seemed like an eternity before she pulled away.

"John, I don't know how to say this. I'm not even sure yet if it's true, but I think I may be pregnant. My period is late," she said, looking upset.

"Well shit. How late?" I asked.

Beth replied, "a couple of days. It could just be stress, but I'm pretty sure I'm pregnant."

"And I just blew another load inside of you. Just in case you weren't pregnant the first three times," I replied, shaking my head at our collective stupidity.

"It felt too good to stop and hop off of you. I probably would have lost my orgasm if I did. Honestly, I love feeling you cum in me. I've never climaxed like I do with you. Most guys finish well before I do and then I have to masturbate to get off. Sex with you just feels so right. I don't know what to do about this pregnancy thing, though. I don't think I'm ready to be a mom," said Beth.

"You don't have to do this alone babe. If you are pregnant, it's my fault too. I can't bring myself to pull out. It feels so good inside of you. Whatever you decide, I will support one hundred percent. I love you and your possibly pregnant belly," I said.

I put a hand on her belly and kissed her softly.

"Since we've likely already made a baby, want to go again just to be sure?" I asked.

She kissed me again, pulled me down on top of her, and said, "Let's make a baby."

Part III to follow.