This happened not that long after I started high school, so I had to be around 14. If you looked at my brother and myself, you would never believe we were related, much less brothers. He was 17 and about 6'2" at the time, blond hair and a slim, fit build, and he was also on the schools' basketball team. I, on the other hand, was about 5'7", dark hair and glasses. Not only that, I was shy and kind of a bookworm. He definitely took after our dad, and I definitely took after our mom. Even still, as different as we were, he really did care about me and looked after me, especially at school. I remember one time he passed behind me with a couple guys he knew when I was at my locker, and I heard one of them say something about how he had such a nerd for a brother. I then looked back and my brother grabbed him by the shirt and held him against the wall. He told him if he ever made fun of me like that again he would beat the shit out of him. He looked pretty surprised and backed off, and that was that.
Anyway, the real part of this story happened at home on a Saturday. Our parents were going to be gone for the day, and by the time I woke up we had the house to ourselves. I went downstairs and I saw that he was sitting on the couch naked. This wasn't that big of a deal, I've seen him naked plenty of times, either getting out of the shower, changing for the pool or even just laying in bed. This time was different though, because he was watching a porno movie and he was stroking his penis, which was stiff and sticking straight up. I went down by him and asked what he was doing and he just looked over and said "just masturbating...you know." Actually, I didn't know. Like I said before, I was shy and at the point hadn't even looked at a dirty magazine before. This was also about 20 years ago so the internet wasn't really around to look this stuff up, so I was clueless. I just shrugged and said "no, not really." He then looked back over at me with kind of a surprised face and said "you mean you've never masturbated before?" I just shook my head. "Boy, you really are a late bloomer. OK, I'll show you, take your clothes off and have a seat. Just don't tell anyone about this." I was pretty nervous, but I pushed down my shorts and underwear and stepped out of them and sat down. He looked over and saw how I was and said "no no, shirt and socks too." I sat back up and took off my shirt and peeled my socks off, then put my feet up on the table like his. He then told me to watch the movie until my dick started to get hard. Well, being my first porno movie, it only took a few seconds before mine was standing at attention like his, although not as big. At that point I was probably about 5 inches, his maybe 6.5. I told him it was hard, and then said "OK, pay attention to the parts you like, and start playing with it like I am so it really starts feeling good." I started rubbing and stroking it, but I was going pretty slow. I said I really wasn't feeling anything and he looked over and said "no, you aren't going to get anywhere going that slow, here." He then leaned over and moved my hand and wrapped his around my shaft. He then started pumping fast and hard, my balls slapping down with every stroke. This is what did it, the feelings were incredible and I couldn't help but let out a high-pitched moan and told him not to stop. I leaned my head back with my mouth hanging open, and after maybe 30 seconds of him stroking, it happened. All the feelings rolled through my penis all at once and my first orgasm hit me like a train. All I could do was let out a sharp "OH! UGH!" as I rolled over onto my side and held onto my fire-hot penis while it kept throbbing. A few seconds later I heard him say, "damn bro, that one must have felt really good, your toes are still curled!" It took me a few seconds but finally I sat back up and was able to catch my breath and talk again. "That's masturbating? No wonder you were doing it, that felt awesome!" "yeah, I usually do it once or twice a day now, but when I was your age sometimes I did it 4 or 5 if I had the chance. I couldn't keep my hands off of it." He then asked me if I came, and I didn't know what he meant. He looked over at me for a second and said "nope, still dry. It'll take a little bit before you start to cum." I asked him what he was talking about and he just said "you'll see, now it's my turn."
He went back to watching the movie and when his penis was fully hard again he started stroking, not quite as fast as he did with me, but still pretty quick. I must have sat there for 10 minutes just watching him work, when finally he said he was about to cum. He then held his breath and started making really short strokes, when all of a sudden white stuff shot out of his penis all over his chest. He grunted a couple times and after a few shots he started stroking hard and fast again, and a few seconds later more started flowing out slowly onto his hand. He squeezed out the last little bit and told me that's what cum is. He then got up and went to go wipe it off, then came back and sat with me again. He started telling me how pretty soon I'm going to start cumming and how I need to figure out a way to get rid of it, he said he usually uses a tissue or the shower, but I could also use a sock if I didn't mind that mom would know what I was doing. We talked about it for a little while until my erection came back. I asked him if I could do it again, and he said I could do it as much as I wanted. I leaned back and started stroking myself again, this time going harder and faster like he did. This one didn't happen as fast, but about 5 minutes later it happened again, and I doubled over in pleasure. Just by watching me he was hard again as well and masturbated a second time with me before the movie was over. Afterwards we just sat there talking for a little while, both still naked. We stayed that way until the garage door opened, then I hurried up and got dressed and he grabbed the tape and went back to his room, then came back down a few minutes later, no shirt and barefoot, acting like nothing ever happened.
After that day I started masturbating on a nearly constant basis, before school, after school, before bed, pretty much any time I had the chance. And he was right, a couple weeks later I started shooting cum. We also did it together sometimes when we were alone until he went to college, as he didn't mind masturbating with me, as long as I kept it a secret, and I have, until now that is.