This was sometime last year in July, when our basement was getting renovated, and my step-bro had to sleep in my room.
During one of the two nights that my step-bro had to sleep in my room, the room began to get really warm. Mike, as we'll call him, and I have always been curious about sexuality, and we've talked about it often. We'd rub each others genitals before, and it felt GREAT! But, we never climaxed. But that night, we were watching tv when Mike began to make a noise. I looked over, and he was stroking his dick.
I walked over, and asked if I could do it with him. He said yes, and I decided to surprise him by grabbing his dick, and began to stroke it. Then, some weird liquid spewed out, which I later found out was sperm. Then I sat back and he grabbed my dick. It felt awesome! Then it suddenly felt really good, and I almost asked him to stop, Then my entire body felt great. That same liquid (sperm) didn't come out, though. I was kind of a late developer.
Since then, we've had these little sessions a couple times a week.