When I was a little younger younger, probably 16 or 17, I remember one occasion when I was able to take advantage of someone and how much power I felt while it happened.
It was during the summer and my younger brother had a friend over to stay the night. He was kind of a cute kid for his age, about my height and blond hair, and he showed up in a white shirt, gym shorts and flip flops. It was a pretty hot day and they were outside for most of it, so later on that evening they took turns taking a shower. When they were both done I decided to take one too, but when I went to put my dirty clothes in the hamper I saw that a pair of my panties were close to the top. There was no reason they should have been so I grabbed them and felt that they were wet. I opened them up and there was fresh cum smeared inside them. Needless to say I was pissed. There was no way it was my brother because it was the first time it ever happened, and it would be pretty weird if that was the case so I knew it was his friend. I took my shower just thinking about what I saw, and I realized I could use it to my advantage if I really wanted to.
After I got out I went downstairs and saw them watching TV, him acting like nothing had happened, but I knew better. I went back upstairs to my room and waited for him to pass by, and with all the soda they were drinking it didn't take too long. When he was done in the bathroom and opened the door, I was standing right there. I quietly asked him 'did you jack off with my underwear?' he got kind of a worried look on his face and denied it, and I said back to him 'oh, so I don't have a pair of underwear in the dirty clothes covered with cum? I'm only going to ask one more time, did you jack off in them?' He almost looked like he was about to cry and said 'yes...but please don't tell anyone...please!' 'Don't worry I wont, but later on you're going to do something for me.' 'I will, just please don't tell him, I'll do anything!' I started walking away and just told him 'I know you will.'
The rest of the night felt like an eternity, but a little while after midnight I went back down to the living room where they were sleeping. They were maybe out for an hour or so but I nudged him awake. When he came to I just whispered to him 'come on.' He followed me up to my room and I told him to close the door. I turned on my light and laid down on my bed and said to him 'so you like to jack off into my underwear, well you're going to do it for me here, right now.' All he could say was 'w-what?' 'You heard me, if you don't want me to tell my brother what kind of a pervert you are, you're going to masturbate for me right now. So go ahead and strip.' His hands were shaking when he agreed, and he slowly took off his shirt and pulled off his shorts, standing there in his white underwear, his penis already stiff. I nodded and said 'those too, completely naked.' He instantly turned red then pushed them down, stepping out of them and staring at his feet. he stayed there for a few seconds and I told him 'OK, you may as well start.' He looked up at the ceiling and grabbed his penis, nervously stroking it. At that point it really wasn't too big, maybe 4.5-5 inches, so his strokes were pretty short and quick. He did this for maybe a minute when I told him 'here, I know you like these so they might help.' I slid my panties down and dangled them off of my toes, telling him to use them. He took them and wrapped them around his penis, stroking again, and I quickly saw a wet spot start to form on them. I told him to look at me while he did it, and I just laid there on my bed with my hands behind my head, knees spread apart so he had a full view of my bushy vagina. His mouth hung open and seconds later he quietly panted out an 'ah, ahh, ah..ahhh...' I saw my panties turn dark, and I took them from him, looking at the young, hot cum inside them. I just sat there for a minute and I saw that he was still rock hard, twitching with every heartbeat. I said to him 'you're still hard? Well, I guess you could go again.' 'Now? I don't think I can...' 'I know boys your age can cum a lot, how many times do you masturbate every day? Four? Maybe more? Go ahead and try.'
He wiped his eyes and started stroking again, his penis red and damp, making squishing noises with every stroke. It took longer this time because he just came, but eventually he started breathing heavy again and I asked him if he was about to cum, and he said he was. I focused on the head of his cock, and moments later he came again, a small amount of cum spitting out, rolling down his hand. After that orgasm he quickly sat down, trying to catch his breath with his head between his knees. I got up and told him 'OK, I guess that's enough, you can go back downstairs, and don't worry, I won't tell anyone.' He slowly got up and got dressed, leaving and closing the door behind him. I was so horny I couldn't stand it, and as soon as the door shut I pulled off my shirt and started rubbing myself, my first orgasm coming in less than a minute and I came three times before I turned off my light and rolled over, barely being able to believe what I had just done. I had never felt that way before and if felt great. I fell asleep feeling amazing.
The next morning when I woke up I heard something outside, I looked out and they were in the street shooting a basketball, both shirtless and barefoot. I was still naked from the night before, so I just watched him, slowly rubbing myself to a quick orgasm. I figured that even though I spied on him while I masturbated, we were even for what he did in the bathroom.