He was immediately embarrassed as hell, scared I'd say at that point... I told him it was OK, I understood his curiosity and wouldn't tell them... commented that he had a nice one for his age, and that it would get like mine by the time he was my age. Fast forward to bedtime, sharing my room and single bed, and I just totally undressed as he was getting his pajamas out. He asked why I didn't have any pjs, and I said it was summer, hot, and that's the way I slept. I got in bed naked, but he took his tighty-whities off, put his jammies on, and got in. After a while I said again that I understood his earlier curiosity, wouldn't tell, and if he wanted, he could feel me down there.
Took a while, but before long his fingers started exploring and I was ecstatic at the touch of his fingers! All kinds of questions, all the time feeling my balls, boner, pubic hair. Didn't take me long to tell him from what I'd seen earlier he had a nice one for his age, and since he was feeling mine, could I feel his too? He hesitated, I assured him again I wouldn't tell, because I knew it was natural for him to be curious at his age - that it felt really good him feeling mine, and knew he'd like that feeling too.
DAMN! reached inside his jammies and there was this majorly stiff little peepee, sticking right up against his belly! Just at the touch of his stiffness my own did a major jump. Finally he got out of his jammies, and it was a long session of mutual 'exploration'. With several 'overnights' after that, there was no hesitation on his part to keep 'exploring' with Cousin Bill! Would I like to experience that again with a kid? Yes, but sure isn't in the cards of reality today!
With succeeding overnights didn't take long to introduce him to the pleasure of getting sucked! Took a while to convince him it was really 'dirty', and when he found out good it felt to have me suck on his he liked that a lot. Will say, didn't want to push him too far by asking him to suck me, and was enjoying the thrill of sucking him while he'd be stroking my shaft and playing with my balls! I loved the sensation of feeling his bulbous little butt cheeks while sucking him. I always quit when I couldn't hold it anymore, would reach out and grab a bunch of tissues to shoot my load in. Only did that twice, and he wanted to see what was squirting out of my 'peepee'.
The next time, after we'd gone through our 'routine' I stopped, rolled on my back, whipped the covers, and let him finish me off, squirting my cum shots up and onto my belly. Will never forget the look on his face, eyes and mouth wide open. I told him I only let him do that, and watch how it came out because I understood his curiosity, and promised him I wouldn't tell his mom and dad what he'd done and seen. Guess that good enough for him, because he never told on me either!
Never did get to 'play' with him when he reached puberty, and often thought about how his 'package' had developed by then, wondering how it would have been to be sucking him then, swallowing his cum spurts!