For your mental imagery, my SIL is 30 years old, long blonde hair, 5’5″ 140ish lbs, plump pouty lips, 36DD juicy tits, big round ass and nice plump pussy from what I can tell.
A little backstory before the fantasy. It was the 1st of many occasions I was lucky enough to feel the forbidden fruit of my SIL beautiful booty. She needed some work on her car done and asked for my help. Which I happily obliged. While doing said work I needed her to help with a few things. It was a rainy day and I had her car in my garage. I asked her to work all the lights and she leaned in the door with her ass sticking out at the perfect viewing position for me. So I let her do a bunch of stuff just so I could continue to admire it. Once I didn’t need her help any longer she said “Oh it’s raining hard now!” I got real close to her to look outside and said “Why yes it is.” We stood real close for a few minutes, when I gave her a couple pats on her lovely ass and said ” Hurry or you’ll get soaked!!” After a second she took off running back inside. That’s how that ended… but here’s what my fantasy would look like…
…after the pat on the ass she would have turned to me and smiled. With that smile I’d reach out to grab her ass, she smiles even more. She turns around my hand still on her ass and pushes me against her car, presses her body against mine and just stares in my eyes. She can feel my cock getting hard against her pussy. Her DD’s pressed against my chest. I feel the warmth coming from her crotch. I slide my hand from her ass now to her warm little pussy. As I touch it she lets out a little moan. She then reaches down to feel I’m fully hard for her. She rubs my cock over my pants and says “Wow my sis is lucky to get to fuck this whenever she wants!” I continue rubbing her pussy through her pants and can feel the fabric getting moist. So I reach into her panties and her pussy feels shaved clean and is so wet for me. I rub her clit and she moans some more. Slowly I slide my finger into her pussy. It’s so tight, wet, and warm. Meanwhile she’s taken my cock out and is stroking away. God it feels good in her hand. I want to make her little pussy cum so I start to finger her faster and she strokes me faster. I can feel her pussy start to clench around my finger. I tell her I’m about to cum and she says “Me too!! Keep fingering me!!!” She stops stroking and I feel her pussy clench again and she’s gotten her much needed orgasm. Then she pulls her pants and panties down to about mid thigh and tells me “I want you to cum in my thong!!” She starts stroking my cock and rubbing my head against her soaking wet pussy. It only takes a minute before I’m exploding all over her pussy and thong. “Wow!! That was a lot of cum!! I’m going to love feeling it soak into my pussy the rest of the day!” We both say that was amazing, she gives me a peck on the lips and heads back into the house….
Source: reddit.com/r/eroticliterature/comments/jce3nh/1st_of_many_sil_fantasies