Step-sister stunned by my manhood in every encounter

My step-sister is always taken aback when she sees my manhood. It's not that she's prudish or anything, she just can't seem to get over how huge it is. Every time we're alone, she can't help but stare at it. It's like a monster, hanging there for all to see. And every time, she ends up giving me a blowjob. She's not too bad at it, considering the size. But the real fun starts when we actually fuck. I can feel her tight pussy struggling to accommodate my massive cock. But she's a trooper and takes it all in. The pleasure is too much for her and she moans in ecstasy. The climax comes when I fill her up with my hot load. She's not my actual sister, but a hot 18/19-year-old who loves a challenge. And I'm more than happy to give her one every time.