Until she reached the age of twelve, my young sister and I used to sleep in the same room. Linda, that's my sister, is two years younger than I am and until that time we had been living in a two bedrooms apartment and there was no other choice on the matter. When she turned twelve, mother and us two kid, we moved into a larger apartment since mother got a promotion at the statistics agency where she was working and we now could afford it.

After moving into our new apartment with its three bedrooms, mother felt much better since my sister and I, we no longer had to sleep in the same room. More often than once, I had heard mother say that it was not proper for a boy of fourteen to be sleeping in the same room as his sister. Of course at the time I couldn't exactly see why she was making such a fuss about a small detail like that, it certainly wasn't bothering me that much.

Just before we moved to our new apartment, she was even considering having Linda's bed being moved into her own room which was not very big.

During the first couple of nights in our new apartment there were no problems as each of us had its own bedroom. I immediately saw the advantages of being alone in my own room since now I could look at my girly magazines without risking being discovered by Linda. But on the third night, Linda who until then had never slept in a room of her own, began to have bad dreams and she no longer wished to sleep by herself in her room. For half a dozen nights in a row she would come barging into mother's room in the middle of the night refusing to return to her own room. Linda definitely didn't want to sleep by herself, ever since she had been a baby she had been used to have me in her room and she now found all sort of excuses to climb into mother's bed barely an hour after she had retired to her room.

I must say here than mother was a widow and ever since the death of my father, four years previously, she didn't go out on dates very often. But she probably expected to get married one day and she still kept the large bed in which she and father slept when he was alived.

Linda and I, we each had a single bed and because of the fact that mother had room to spare in her bed, Linda would go there whenever she was afraid and this was mostly every night.

Soon mother got tiered of being awaken at all hours of the night and she decided one night to lock her bedroom's door from the inside.

When my sister realized that mother's door was locked she felt that she had no other choice but to come into my own room.

I will always remember that first time that she quietly opened my bedroom door well after midnight. Even though she didn't make any noise when she entered my room, I still heard her enter, I even watched her slowly approaching my bed in the dim light coming from my window.

She was very scared, it was plain to see since she was shaking and the minute she realized that I was awake she begged me to let her climb in bed with me.

I became angry at her since there was barely enough room for me in my bed, but I was so sleepy that without thinking further I threw the blanket over and I made room for her next to me. Half a minute later I was fully asleep.

But a couple of hours later, I got up to go to the bathroom and when I came back Linda was taking most of the space in my bed and I had to squeeze in next to her.

Without even being fully aware of it, my cock was pressing against her developing bottom, I could even feel the heat of her bottom's cheeks against my groin and soon my cock was very hard. I knew that there was only the thin material of my pajama as well as her own pajama that was separating my cock from her girly rump.

Before that night, it had never occurred to me that my sister could be sexually attractive, but now that I could feel her round buttocks, - in the last year Linda's body had begun to change into that of a woman - I began visualizing her in a completely new perspective. Her hips had begun to flare out and her breasts were now the size of large oranges, even the baby fat around her thighs had begun to be replaced by muscles.

To make matters worse, she was constantly trying to shove her bottom against me as she tried to seek my body heat inside the cold apartment.

For the remainder of the night I wasn't able to sleep at all, as soon as I felt her bottom against me I had trouble restraining myself from shoving my cock against her warm behind. I knew that it wouldn't have taken more than a dozen shoves before I would have paid tribute to her bottom with a load of cum, but I feared too much what the consequences would bring afterward.

Finally in the morning, I heard mother calling us from the kitchen. As soon as Linda heard mother, she turned toward me and she begged me not to say a word to mother about her coming into my room. She wouldn't leave my room until I agreed to keep my mouth shut about it.

As soon as she was gone I seized my cock in my hand and I began to pump it until I experienced the relief of a climax.

That same evening, not very long after I had climbed in bed, I heard my sister entering my room once again. The previous night I had enjoyed her presence in bed with me, but at the same time I knew that while she was lying next to me it was difficult if not impossible for me to sleep with her so close to me.

But before I had given her my approval, she was already cuddling against me and I hadn't the heart to tell her to leave.

In a few minutes she was sound asleep whereas my cock was stone hard and pressing against her bottom once again. For the next two hours I fought a battle of will in my mind, one part of me wanted very much for me to rub my cock against her full bottom, while the other part was trying to prevent this. I knew that if I was to succumb and to give in to my desire, it would be incest, but as the minutes went by I could tell that my pulsating cock was getting closer to tip the scale in its favor.

Then at last, being no longer able to restrain myself, I slowly began to shove my twitching erection in the crack of her bottom. It didn't take very long for my boiling spunk to spurt out of my cock in jets and thus soaking my pajama. Even as the last pulse of pleasure was squirting my seed against my sister bottom, I knew that the thin material of both of our pajamas was now very wet.

My sister never realized what I had done to her that first night. Again in the morning, just before the light of dawn, I fucked her bottom one more time and by now I knew that the material of her pajamas over her bottom must have been soaking wet.

When she got out of bed about an hour later, she kept pressing the flat of her hand against her bottom and I knew that she was investigating why she was so wet.

But she didn't say a word as she left for her room. Surely I told myself she must know by now what I had done this to her and she certainly wasn't going to come back into my room again.

But she did come back that same night. It was later than the previous night and I knew that she had probably tried to stay in her room. But her fear of sleeping along was greater than the fear of feeling my erection pressing against her and once again she was soon lying close to me in my bed.

I was a little disappointed when she remained on her back instead of lying on her side as she usually did. In this new position her bottom was no longer available to me.

After a little over half an hour, I still couldn't sleep, my cock kept twitching in my pajamas as if it was trying to remind me of the presence of my sister lying next to me. But during the night, while she was sleeping, she turned over on her side and her rump was pressing against my cock once again. By now she seemed to be sleeping and I was very careful when I began to shove my eager cock against the crack of her bottom. But all of a sudden, I felt her body moving. She suddenly turned on her back and in what seemed to me at the time as a much too loud voice, she asked me what I was doing.

"I was just turning around." I said in a trembling voice.

"No you weren't. You were pressing yourself against me and I want you to stop doing this."

I knew then that she hadn't been sleeping at all and when she had turned on her side she probably thought that I was sleeping. She seemed very angry at me and by the high pitch of her voice I could tell that she was close to tears.

"Well you know that my bed is too small for the both of us, why don't you go into your own bed if you don't like it here."

"I will tell mother what you were trying to do if you ever try this again." She was in tear now.

"Fine with me. Mother will probably want to know what you were doing here in the first place. Remember you are the one that is in the wrong bed, not me."

There was more crying and I really felt sorry for her, but I had to act this way with her since I knew that mother was going to kill me if Linda was to tell her that I was rubbing my cock against her.

"Why are you doing this to me? You know that I can't sleep in my room all alone."

"I can't help myself. Each and every time that you are lying next to me I have trouble falling asleep unless I..., well you know I have to find release somehow otherwise I will remain awake all night."

I knew that she and her friends often talked about sex in school and being twelve she certainly was well informed on the matter. She knew exactly what I had been doing to her.

"You're my brother, you can't do this to me. This is incest, it's horrible of you to treat me in such a way."

"Listen Linda, I can't help myself. As long as you are in my bed, I find it impossible to sleep unless I get this release first. Even though you are my sister, you are a beautiful and sexy girl, you can't blame me for finding you attractive."

This seemed to calm her a little but I could tell that she was still on edge, even as we talked she was trying to keep her body as far away as possible from me.

"Well I want you to stop doing this. If you promises me that you will never do it again, I won't tell mother."

"You know I can't promise that since I have no control over my erection."

Never before had I used such a word in front of her and now that it had escaped from my mouth it made me feel even more lewd.

"I don't like it when you do that. It's wrong."

"Then go back to your room and I won't bother you. It's also wrong for a sister to sleep in bed with her brother."

Again she began crying, I now felt very bad about the whole thing. Without thinking much about it, I shoved my arms around her and I pressed her against me in a protective manner. There was nothing sexual about it and it was an expression of genuine brotherly love. But even as she kept crying in my arms, I could feel my cock twitching more than ever. I knew that it was certainly not out of brotherly love that it was doing so.

As I tried to calm her down a little, my lower body, as if having a mind of its own, began to rhythmically press against her waist and even though I knew what was happening, I couldn't stop myself. Linda was now behaving like a trapped animal, even though she was trying to get as far as possible from my poking cock, her resistance was weak but at the same time I could tell that she was finding comfort in my arms.

Then the crisis was upon me and while I felt the intense pleasure of a climax, I also felt my spunk jetting out of the tip of my cock. Even after the grand crisis was over, I continued to hold her tightly in my arms while keeping my now soft and sticky cock pressed against her waist.