My step sister and I have always been pretty close, we're pretty much the same age and even though I think she's really pretty she's never been into men so there wasn't ever any awkward sexual tension between us like most step siblings nowadays. So when I heard her crying in the other room I did what any decent step brother would do and went to roast her a little until she cheered up lmao That idea fell apart almost instantly though cause it seemed pretty serious, her and her girlfriend were fighting and this girl had been over to family functions and everything and she always seemed chill to me but apparently that wasn't the case. My step sis was locked in to the idea of getting back at her. I was happy to help brainstorm because fuck that girl, and but I was not ready for her to hit me with her grand plan to really stick it to her. My lesbian step sis looked me square in the eyes and asked me if I would fuck her and cover her in cum so she could send a truly devastating pic to her ex. Obviously I needed to collect myself for a second, but at the end of the day, what are friends for, its not like I'm gonna sit here and lie like I've never fantasized about her before, I'm only human after all, lucky me I'm really good at eating pussy, so it wasn't a crazy stretch to start getting her warmed up, I felt particularly accomplished every time I felt her body flex and I was over the moon when she came on my big soft tongue. What WAS crazy though was how good this girl was at sucking dick, her warm wet throat gave me goosebumps almost instantly and my mind was absolutely disintegrated when she got on top of me and started riding my throbbing cock. I guess how close we'd gotten really payed off cause despite our differences she seemed to really love every inch of me pounding deep into her perfect soaking wet little pussy. lucky she was focused though cause I'd almost forgot WHY we were fucking at this point, she grabbed my rock hard cock and started diligently stroking and sucking and tasting herself until I exploded all over her pretty face. She wanted a good picture to send this girl, and every additional pump of hot sweet cum that hit her face and tongue was an additional sticky reminder to her ex how badly she had fucked up. I deliriously watched her take a selfie and could not have been happier I'd been able to help