I was sitting at my desk in my bedroom when I heard the patio doors downstairs open. Being the summer holidays, my parents were at work so I knew that the only person in the house was my 12-year-old sister Selina. Having heard the girl say she would do a spot of sunbathing earlier, I hit the pause button on my computer game and peered out of my bedroom window.

It was a hot, sunny day and was fully of warm promises of endless relaxation. Well, not quite endless, but certainly six weeks without school. At seventeen, I was going to be in my final year soon, but right now I just wanted to laze around and enjoy the summer break.

As I looked out into the large garden, I spotted Selina walking out into the lawn, and my cock suddenly grew in size.

"Fuck," I whispered, lustily.

Selina was only four-and-a-half-feet tall and skinny like most twelve-year-olds, but whilst her chest wasn't very developed (I notice these things, you know) she had a little widening of the hips and a tiny amount of puppy fat that gave her arse a lovely roundness that attracted my eye at every moment.

It was arousing enough to see her in a tight pair of jeans, or the little black skirt that she wore to school, but now she was wearing a two-piece bikini as she padded across the lawn in bare feet, carrying a blanket in one hand and a girlie comic in the other.

When she reached the middle of the grass, Selina lay out the blanket, bending over away from my vantage point as she did so, and I unzipped my flies as my eyes fixed on her cute little arse. The bikini top she wore was more of a half-T-shirt that hugged her barely developed chest and showed off her flat little belly. The bottom part was white and part of the material round the back had run up her arse-crack a little. Gently, I stroked my stiffening prick in my hand as my sister got on all fours to lay out the blanket properly. Then she stood up and I was seriously pumping my dick now, and when the little nymph idly hooked her thumbs round the back hem of her bikini-bottoms, and tugged out to pull the material that had run up the fold between her buttocks, I cried out and shot my load.

"Oh God," I panted, my sticky cum flying into the air, running down my fist, splashing onto my shirt.

I kept my eyes focused on Selina as she turned - not glancing in my direction at all - and sat down. "I want to fuck you," I whispered whilst still stroking my softening cock, admiring Selina's pretty little face, dotted with freckles and bordered by short, jet black hair.

Daintily, the little girl lay on her back and put some pink-framed sunglasses on. I got up and went to the bathroom, where I wiped my hand down and changed my clothes.

"Stephen," I said to myself as I looked in the mirror, "You gotta fuck that slut."

I grinned at myself. When I first started lusting after my little sister, about six-months ago, I had been a little ashamed. Then I soon realised that Selina was so damn sexy that it mattered not that we were related. If anything, growing up together - me the protective big-brother, her the impish, giggling little sister - was a good a reason as any to desire her.

Strolling back into the bedroom, I sat at the computer. I didn't really feel in the mood to play games, so I flicked the machine off and glanced out at my sister again. I sighed.

Then I began casually looking over at the high trees at the end of the garden and remembered back to when I'd lost my virginity.

I'd been fourteen and my parents and sister were visiting some relative for the night, leaving me to be looked after by Jane. Aged twenty, Jane was a Goth-chick who was actually quiet pretty despite a weird appearance (purple hair, black lipstick, serpent tattoos and all black clothes). She sure had a fine fucking arse anyway, and nice tits.

Within an hour of everyone leaving, Jane wasted no time in seducing me. Actually, she didn't really seduce me, as that implies some sort of subtle, sweet mutterings of love. Jane just asked me if I had a girlfriend (no), whether I had ever had sex (no), if I ever thought about sex (er...yeah, sure) and finally, whether I wanted a fuck (Erm...).

She sucked my cock like a real pro (that's not strictly fair. She didn't charge me anything) then took me into my own room where I fucked her. Then I fucked her again, we watched some TV then I shafted her one my time in the living room and then again in the bedroom. In the morning, we did it again until my parents and Selina returned.

After that, I felt pretty confident with girls, and at fifteen dated a girl a year older than me, who I slept with often. My mom and dad felt the need for me to be babysat when I was to be left alone for another night when I was sixteen. How happy I was that Jane was still around - still dressing up all in black and still fucking horny.

That evening, the horny young woman introduced me to anal sex, and I fell in love right away. Pussy fucking was good, but I just couldn't believe how good it felt to have my six-inches of throbbing cock-meat wedged in the tight arse of this woman. I fucked her arse all night and most of the next day too. Then I went round to her flat the next weekend when her boyfriend was away and pumped her arse all night there.

Sadly Jane had to move away, and the couple of girlfriends I had after that weren't to keen on anal. One permitted it a few times, but wasn't impressed when I told her - truthfully - that I would rather fuck a girl's arse once than fuck her cunt on a hundred occasions. Of course, if a pretty girl had invited me - an anal addict at 17 - to fuck her cunt, I wouldn't say no. But I'd rather not bother with girlfriends and sex if I can't take the passage that I prefer the most.

Back in the real world, I detected movement in the corner of my eye. Glancing to my sister, I watched with excitement as Selina turned onto her belly and lay her pretty little head on her folded arms. Her buttcheeks - clad in that tight little white bikini bottom - were pointing upwards and my cock began to throb in my jeans again.

With no hesitation, I knelt on the floor with just my head peering over the window ledge, eyes fixed on my sister's arse whilst I pulled out his cock and began tugging once more. Soon, I shot my load, spraying the wall directly in front of me with sperm as I gazed hungrily at Selina's bum.

"Oh Selina," I panted.

Frustration nagged at me as powerfully as lust.

It was nine o'clock and Selina's bedtime when I plodded out of my room. The evening was warm and I wore just a pair of black shorts and a white T-shirt as I stretched my legs whilst walking down the hallway, body aching from a good three hours of hunting porn on the 'net. The door to bathroom was slightly open, but I didn't bother considering that there was someone in there just because the light was on. I wandered in and stopped in my tracks as I saw Selina standing at the sink, brushing her teeth and wearing just a white vest and a pair of pink knickers.

"Oh, sorry Selina," I stammered.

"S'okay," my sister replied as she turned her head, her words slightly distorted from the tooth-brush that she was shoving back and forth in her mouth. She cared little that she was wearing just underwear in the presence of her brother.

"I'll use the downstairs toilet," I said, and turned to leave, though only after having a quick but thorough glance at my sister's cute bum in those adorably, pink panties. I committed the image to memory as I walked down the stairs, knowing that I'd bust my balls repeatedly that night over the sight of that arse.

Mine and Selina's parents both worked hard, leaving the house at eight in the morning together, and arriving home at around five. They earned a good wage and did not pressurize me into getting a summer job at all. I had all the pocket-money I needed, and mom and dad considered studying over the summer far more worthwhile than doing some shit job for minimum wage.

So, it was another lazy day for me and my sister. Selina was watching TV downstairs whilst I sat at my computer once more.

My stiff cock was pumping in my fist as I flicked through the thumbnail galleries on an anal-sex porn site.

When I heard footsteps scampering up the stairs, I stuffed my cock into my jeans and hit the emergency-link to a more innocent site.

Selina never knocked, and indeed, on this occasion she fulfilled my expectations by happily barging into my room.

"You hungry?" I asked her.

"No," Selina shrugged, her cute little face looking so wonderfully pretty and impish.

"Whaddya want?" I enquired, "I was assuming you wanted me to cook lunch or something."

"Nah," the girl smiled, "I just want to borrow that CD I bought you for your birthday last week."

"Oh, I see. You only bought it for me in the hope that you could borrow it?"

"Pleeease?" Selina begged with delicious, childish pleading in her big brown eyes, "Go on, be a good big bruvver."

"Sure, it's over there."

The CD was on the bed, along with a few others.

Selina walked up to the bed, not noticing my eyes following her.

She bent over a little as she stood at the end of the bed, looking through the small pile of albums.

"Cool," she chirped to herself as she looked at the cover of one CD.

I admired her, my cock throbbing hard in my jeans and trying to get out of the half-closed fly zip.

Selina wore a thin white-T-shirt (no trainer bra underneath yet - no need) and a pair of tight, blue cotton shorts. Her slim, pale legs were all on display, with her feet clad in a pair of ankle-length white socks.

"Fuck," I whispered, eyes fixed on that lovely little rump in front of me.

Like an automaton, I stood up and walked over to Selina, who was still standing and bent over the bed, obliviously flicking through the CDs.

I clapped a hand to Selina's left buttock and felt the lovely firmness of her arse.

"What a bum you've got," I whispered, lustily.

Selina froze, staring ahead, no longer interested in the albums she'd been looking at. "I love this arse," I added. I ran my hand over her right buttock, then back again, feeling her bum up with no shame. I was preparing myself for my sexy little sister to scream or run out the room or slap me or something! But she didn't, she just remained there.

Leaning a little, I could see the side of Selina's face, and she seemed to be merely curious and anticipatory in demeanour rather than worried or anything.

"Are you okay sis?" I asked her. As overcome with lust as I was, I didn't want to be forcing my sister into anything.

She didn't reply.

Standing directly behind Selina, I gripped the bottom of her shorts and tugged a little. Her arse may have been nice and rounded, but her waist was narrow and the shorts slid down an inch or two with ease.

"Can I pull these down sis?" I asked.

"Yeah," she whispered. Her voice was shaky, but only through anticipation and not anxiety.

Gently, I slid her shorts down to her ankles, revealing that she wore little white panties with frilly little pink edges.

"And these?" I asked my sister.

"Yeah," she replied, breathing deeper now.

Kneeling, my face level with my sister's arse, I pulled her knickers down and let them fall to her white- socks.

The arse before me personified beauty. Firm, gently rounded and as pale and delicate looking as china. Licking my lips, I slowly kissed her left bum-cheek, moving over and kissing the other. My hands trembling with anticipation, I placed my hands on her bum-cheeks and parted them. Revealed in that cleft between her buttocks was a delicate, puckered little hole, pink and hairless.

"You've got a gorgeous arse sis," I commented.

Selina didn't say anything, but I could hear her breathing hard and once again, she didn't resist in the slightest.

Moving my head forward, I placed a kiss on her bumhole, then flicked my tongue over it and lapped at that tight little arsehole like a thirsty dog with a bowl of water. Then I began to work my tongue against her arsehole, working it into her bumhole and thrashing it around in her clammy, wet rectal passage.

I never had any leanings towards scat-sex, but that created a nice little paradox for me. These angelic little asscheeks, the smooth, firm flesh and the sweet, puckered hole between them, were all designed simply to excrete shit. That's what turned me on so much, licking at my sister's anus and grunting hungrily with my head wedged between her wonderful arse-cheeks regardless of what I encountered up there.. Eventually, I pulled away and tugged off my jeans, socks and shorts. Standing in just my T-shirt, my thick cock jutted out from my groin, rippling with veins and pumped up. Selina looked round and looked with admiration at my dick.

"Whoa," she smiled, and continued to watch as I took a jar of moisturiser from the cabinet.

Scooping up a glob of cold, white cream, I wiped it over my dick getting it all slick and greasy.

"What are you going to do?" Selina asked, even though I could see in her big, warm eyes that she knew.

"Sis," I smiled, "I'm going to stick this lovely big dick of mine up your arsehole."

"Will it fit?" my sister asked.

I noted that she was only concerned with successful completion of the plan, but not in anyway horrified at the prospect of being buggered by her big brother.

"It will," I reassured her, "Get up on the bed."

Selina did so, stepping out of her shorts and knickers and shovelling the CDs off the bed, sending them clattering to the floor. The beautiful little 12-year-old got on her hands and knees with her arse pointing straight at me.

Kneeling up on the bed behind her, I placed on of my moisturiser-slathered fingers against her arsehole and pushed it in.

"Oooh," Selina gasped, "Mmmm."

Working my digit back and forth, I managed to coat her sphincter with the cream.

Then I took my finger out and held my prick in my hand as I edged up to her on my knees.

"Ready?" I asked my sister.

"Yup," Selina replied.

Placing my thick, cream smeared prick against Selina's anus, I took a deep breath and pushed. Selina gripped the duvet and bore up well as my thick prick began to make progress.

Steadily, my throbbing bell-end began to part the lovely little anus in front of me.

"Ooooh!" Selina whimpered.

"You okay?"

"Sure, yeah. Carry on Stephen."

I did so, and suddenly Selina's anus yawned open and let my cock slide halfway in.

"God that's good," Selina cried out, "Oh, God...uh!"

Working my way forward, my prick steadily eased upwards, and soon I was buried entirely in my sister's arse.

"Fucking hell sis," I stammered, gripping the girl's hips, "Fuck, you got a good arse."

I began to hump away, thrusting back and forth and delighting in the feeling of Selina's rectum. It was a hot, clammy tunnel who's entrance was a ring of taut, twitching muscle that held the base of my cock in a near vice-like grip.

"Oh Stephen," Selina cried, "Oh, God it's good. Uh uh uh uh...uh...God...yeah!"

It wasn't long before my balls were rumbling, my orgasm rising.

"Oh fuck," I gasped, "Oh, I'm cumming. Fuck, sis...NNNGGG!!"

My dick exploded, spraying forth hot, creamy wads of sperm into the depths of my sister's bowels. I bucked my pelvis throughout my orgasm, spluttering incoherent obscenities as the last of my cum sloshed out into Selina's arse.

Finally, I sighed in a satisfied way and slid my dick from my sister's gaping little arsehole. She fell forward and lay on her side, breathing hard and clearly happy.

"Was that good," I asked.

"Oh Stephen," she smiled, "That was fantastic. Oh, I didn't think that was possible, getting it up the bum."

"It's the best way."

I leaned over and kissed her thigh, then one of her buttocks, before lying alongside her.

"I want to fuck you again," I told her.

"Now?"

"Well, in a minute. Then twice later. And loads of times tomorrow and...and so on. Sis, we got six weeks of having the house all to ourselves for nine hours a day, every weekday. Then there's the week that mom and dad are going away soon. I want to fuck you all the time sis."

I kissed her on the mouth, delicately, almost like a normal peck between brother and sister.

"Are you going to do it up my bum again?" she asked, sweetly.

"That's the only place," I told her, "I renounced fucking pussies a while a go. You'll have to wait until you get a boyfriend to take your conventional maidenhead, because I'm only going to fuck your bum."

"Fine with me," she chirped, "I loved it. God it felt so...good. It was nice."

"Then hop aboard," I smiled as I lay on my back, holding my re-stiffened prick in the air. Selina eagerly mounted me, facing towards me as she knelt astride my groin and lowered her anus down onto my cock.

"Oh Stephen," she whimpered, pleasurably, "That's so good. Mmmmm."

Soon, my prick was once again wedged fully in her shitter, and Selina rode me with great enthusiasm, smiling happily and lustfully as she felt my dick pounding into the depths of her guts. She tugged off her T-shirt so she was completely naked as she humped my dick with her arse.

I fondled her tiny titties, stroked her thighs, then took hold of her head and pulled her down, kissing Selina heatedly on the mouth. Our tongues flicked and thrashed in each other's cheeks whilst I buggered her. Soon, my prick erupted once more and I drove my tongue into my sister's throat as my dick erupted hot sperm into her anus.

Once more, we were reduced to panting, sweaty wrecks slumped on the bed.

"We're going to have so much fun," Selina said as she cuddled up to me.

"Absolutely," I agreed, "We'll get a few more in before mom and dad come back."

"Can we do it again in a few moments."

"Hey, I'm not a complete stud. It'll take an hour or so to recover."

"Oh, boo," Selina pouted, and giggled.

"I've got to go to the shop," I announced, and sat up.

I got off the bed and started dressing.

"I'll be back in couple of hours," I told Selina, "And when I get back, I want you on your hands and knees with your hungry little bum in the air."

"I will be," she laughed, and stretched out on my bed, lovely and naked.

Unable to resist, I walked over to her and kissed her on the lips, then on the forehead.

"See you later sis," I said as I walked out the room.

"Byeee," Selina called in a sweet, girlie voice.

"This," I muttered to myself as I walked down the stairs, "is going to be a good summer."