OOC I'm open to exploring this story as an incest one. But going with my character being your step father brings in a whole bunch of character angles we can take. The tension of a man who hasn't been there all your life. The daddy issues this can imply for your character. To summarize, I'm actively more interested in a step relationship and the interesting extra details we can draw out from their history with this.

You heard your best friend moan in delight. You'd known her your whole life, you knew what she sounded like. And then you heard me grunt. You knew that grunt. I'd been dating your mother for long enough for you to intrupt us in sex. You knew that sound. You knew that smell. Well, did you know what your best friend smelled like when she was horny as hell?

Your mother was... a dedicated woman. And I did love her. But I was kinky. And she was not. When I'd brought up exploring this she'd acted like I'd slapped her in the face. I'd been hurt. And for a while I'd not strayed. I'd stayed faithful but I'd watched porn. It had been when she had stayed over for your 18th birthday last year that she had caught me watching some really kinky porn. But rather that ratting me out she was interested. We'd gotten each other off. And... well, now we were each others. She was my toy. I was her owner. And we were happy.

That's what you'd just walked into. She was dressed in a collar heels, nipple clamps and a smile. My cum was on her face, and she held a glass of wine for me. She was panting as I put a toy aside I'd just used on her. And then she curled up at my feet. "Fuck Sir. You know how to use me good. I'm sorry you couldn't be there for my 19th."

I smiled at her. But then she saw you, and froze. Her mouth parted. I saw her look and saw you as well.

But, well, you didn't tell your mother did you? Something pulled you into that room. Something draw you in, turning our little couple into a throuple. Something pulled you to join your best friend at my feet. What was that?