"You don't mind, do you," was the whisper I heard in my ear as I awoke to find big sis lying halfway across my body.
One of her hands was holding mine down on my bed as far from my body as it would go, the other was wanking hard on my penis.
"After all, it is my 75th birthday."
No I didn't mind. Just surprised to be wakened up like this in the middle of the night.
On the whole, she does not like birthdays now and I wouldn't know if she had liked them as a child, I was too busy with myself and my own friends most of the time. But this had been a good day for her. Cards from two dozen people, one nearly old enough to be our mother, others from her children and grandchildren and some from surviving former colleagues.
I had made sure there would be enough time in her schedule and hired a limo to take her on a round of flying visits to various people I had prepared to meet her. A very nice lunch for her and the limo used it's speed to bring her back to our shack in time for her to cook the evening meal she wanted to present to certain friends.
It was a very nice meal too. She is good at that. The guests left with a warm feeling still growing in their warm bellies. They also left behind a new dishwashing machine running quietly behind a closed door.
That night we had actually kissed each other in public. An innocent kiss between brother and sister. Kisses aren't always sexual, this was the sensual satisfaction of our bodies.
Darkness had fallen before we went to our own beds and before we parted to our separate rooms it was a sexual, almost a longing kiss. I pushed in against her big belly trying to get my legs against her more solid thighs, to line my penis up with the place where it often used to go. She is still growing.
So when I found her lying over my body she was holding it down quite easily. I could smell the spices from the cooking seeping out from under her arm.
"I put cream on my hands but too much came out. So I wiped it off on my vagina."
She still had plenty on her hand because it was sliding easily up and down my penis. It got longer and stiffer. Stiff enough for her to start feeding it into herself.
By now she had properly mounted me and from previous experience was gripping me tightly about my hips with her tree-trunk thighs. She obviously didn't want me to thrust up into her when she was not ready to accept it as I had often done before.
"Does that feel good," she asked, "Do you like that?"
She knew full well the effect that pushing my penis back and forth in her vulva was having on me. The electric shocks were making me wince with delight. Then she started to put it further in her. Ever so gently. She like to lean forwards over me so her tits hang down and occasionally touch my chest.
She drew my hand back in and put the middle finger almost right on her pleasure spot. She had taught me well about that spot.
"You're getting round... You're so big."
We both knew what our jobs were. Mine was to bring her off. Hers was to let me fire into her body.
Within a minute she was shouting, "Juice me! Do it now!" and lowering her hips enough to encompass the whole head.
That nearly sent me out of my brains but I concentrated on making her come. After all, it was her birthday. I tried not to come right away and succeeded. But she blew. There was nothing that could stand between her and an orgasm. I slipped in another half inch till she stopped me.
"When your penis is there it strokes me on the spot. Did you know?"
"Does it?"
"Yes. Keep it there."
Then as she cooled down, "You came."
"Did I"
"Yes. I can feel your juice. Its so much wetter in there now."
"But I didn't do anything."
"Oh yes you did." She brought up her hand.
"That's your smell! You must have come."
So I had missed my chance for it had I? She began to lie down beside me. As she sank onto the bed I tried moving my hands to find other spots which would excite her but they all seemed the same. Just a big handful of fat.
I desperately pushed one of my legs between hers before she closed them. She was 75 years old but she was not finished with. One of my hands held an ass cheek and I held tight.
We talked. All kinds of things from our parents, big brother, a bit about her ex-husband and when she came to live with me. She didn't want to say much about that but that was when we came to decide about our futures together.
She had hooked up with a few men, sometimes I had offered to be out when she wanted to bring them back and she, I think, had used the time to be alone with them, free from interruption.
Sometimes she said she wanted to see them elsewhere and I did not ask further. She was in charge of her own body and it still looked fairly presentable.
It was after one of those times when I had cleared out for her that I came back to her crying.
"I'm not old, am I? I don't look terrible do I?"
She was sobbing enough to make her face a mess. "You will look fine when you clean your eyes." Another flood of tears.
A bit roughly I pulled her towards me and for some long forgotten reason I chose to lick her face clean. She just hung on to me.
Suddenly she had grabbed me by the groin and was massaging it furiously.
"I want you in me", she said. Her voice was low and demanding. "Put it in me, now".
She had taken me by surprise again but she gave me a decent hard-on to put in her. I was worried about contraception and disease but she growled, "Don't care".
It wasn't the first time I had been in her but it was the first since she married.
The first time was when she said one of her friends was going to have me. This was on condition that I wore a mask so I could not tell night from day. At some times of year this is almost normal of course.
I didn't last long and the main thing I felt at first was the pain in the head of my penis despite the lubricated rubber sheath on it. I would have felt hopeless if I had not gone through with it so I continued.
Then there was no pain. Quite suddenly there was only want. That and the determination to thrust deeper with each stroke.
Then my whole body contracted. Everything from my toes to my fingertips to the blood in my brain was rushing down to my groin.
It went into my penis in spurts as the sperm came out, blasting into this girl's body. I could not care less who it was that my big sis had set up for me. All of her body was now my property.
She set me up again, said that now I was growing into a young man I ought to find out how a man should treat a woman. Now I don't know if it was her every time but I was learning a lot about how to make a woman happy in bed.