Six months ago Cassie my older brother John's wife gave birth to their first child. A month later she turned up at my apartment alone. When I asked if she ok and where John and the baby was, Cassie said they were fine and John was looking after his daughter for the day.
Before I carry on I'll explain something. John is my step brother. Same mother, different father and John is seven years older than me. Cassie however is just a year older than me. Throughout my childhood John would tease me about the size of my cock, saying for a youngster I had a large penis. It got to the stage where he'd became almost fascinated by my much larger cock, but at that age I didn't realize my cock was a lot bigger than most males. Even at his wedding to Cassie he made some reference jokingly to my cock size.
Cassie didn't wait for me to ask her why she was round at my apartment. Instead she put her right hand down to my crotch and rubbed my cock through my shorts. Holding the back of my head, Cassie kissed me and carried on manipulating my cock. I was so stunned I didn't do anything. Only when she went to put her hands inside my shorts did I stop her, but by then I was nearly erect.
Stepping back Cassie said "You know I've always wanted you since we met" As she said it she stepped forward dropped to her knees and dragged my shorts down. I don't ever wear underwear, not because I want to show off, It's because I find it incredibly uncomfortable. My erect cock stood up and out the moment she dropped my shorts and I watched my sister in law gasp with surprise.
She's not the first person I'd seen that face with, but usually it was a males face. That's because I've found men adore my cock more than women. Well that was before Cassie.
I should have said no, I should have known better. But I didn't know when she took my cock into her mouth, what I later found out. Cassie and I had sex all morning and into the afternoon. I fucked my sister in laws mouth, pussy and asshole as hard and as deep as she could take my cock, and that was every single inch. She became a total slut for me and I just couldn't get enough of fucking such a beautiful woman. Not long before she left my apartment to drive home, I got a text message, but didn't check it immediately as I was fucking Cassie's ass in the shower.
When she'd gone and I had chance to go over what had just happened, I scrolled through my phone and found my step brothers text message. It said "Hope you and Cassie are having a good time. Make sure you give her all she wants, I'll phone you tomorrow, after she's told me everything".
John did phone the next day, but I didn't pick up. I did when Cassie's phone number came up on mine as it rang. It was Johns voice though which said "hello". I was so nervous until John said "Thank you for giving Cassie what she's wanted for some time. Believe me bro I wanted you to fuck her just as much as she wanted your cock". I was left stunned, and it took me sometime to respond. When I did all I could say was "Your both welcome". I felt such a dickhead, but John then went on to tell me how much he'd wanted Cassie to have sex with a guy who was well endowed, and who but his younger brother would have been more perfect.
We talked about the times he'd seen Cassie flirting with me, and then asked me why he'd never said anything. It all came back to me as he spoke and I started to understand, this thing that had just happened between me and Cassie, had been something they'd both wanted for some time. The birth of their child had apparently made Cassie determined to have a guy, (namely me) with a big cock, fuck her before she settled down to marital family life. The telephone conversation ended with John asking me if she wanted to see me again "Would I", and try to understand my face when he said this "Would I PLEASE fuck Cassie again".
It had been said by my brother about his wife and I couldn't take it in, at first.
Only now after Cassie has been a weekly visitor to my apartment do I understand the whole thing. John's cock measures five inches erect. He's married to Cassie, a very very beautiful woman, as a kind of marriage of convenience. My brother is a very clever man and has used his cerebral talents to make lots of money. Cassie lives a very comfortable life and John gets to have sex with a stunning woman. But she craves sex with a man who's got a larger cock.
That's where I now fit in. Cassie and I fuck at least once a week. The rest of the time she is totally faithful to her family. But when I say faithful, is she being unfaithful if her husband, my step brother, as he positively encourages us to fuck one another.