A Brother-Sister Experiment Gone Wild

The day I proposed to my brother Alex that we try anal sex, I claimed to be a virgin, and he confessed that he had never tried it before. We followed a gradual plan to minimize the pain for me. I told him that a friend of mine, Mariloli, had recommended it, claiming to be an experienced anal sex addict. My brother eventually found out that I wasn't as addicted as my friend, but I had been receiving it from behind for a year. This plan was just a way for me to mess with him, to make him suffer as payback for something he had done to me days earlier. We ended up even, and we smoked a peace pipe together. Since then, anal sex has become another way for my brother and me to enjoy each other. A couple of days later, I confessed to my brother that Mariloli was real, but her name was actually Sonia. He didn't know her because she wasn't part of my usual group of friends. I told him that she was a classmate at the university, 22 years old and from Tarragona like us, and I invited her to come swimming at our house that same afternoon, along with the other girls. I introduced her to everyone when we were all in our tops, and poor Alex was mesmerized. At one point, Alex pulled me aside and confessed that he had a crush on Sonia, and he loved her small tits and her slightly curvy but proportional ass. He even said that he was having a hard time hiding his desire to fuck her right there and then. Apart from her sexual aspects, he thought she was cute, and he loved the light blue highlights in her long, brown hair. Later that night, I told my brother something that left him speechless. "As it turns out, Sonia is a rich girl from a good family. In her first year at the university, she looked down on me because she knew that my mom is Mexican and my dad is Spanish. But then she changed in her second year, and now she goes around acting like a goth, I think it's a way of rebelling, and we became good friends." "Damn, with her looks and her aesthetic preferences, added to the fact that she's a total slut, my desire to fuck her is even stronger, " he said, admiring and nervous. I laughed because his response was appropriate for what was to come. I told him that she was also interested in him, and that she had just as many desires. Poor Alex was shocked, amazed when I added that I wanted him to fuck her, and even more amazed when I said that I wanted to watch him fuck her in the ass. Alex burst out laughing, and there was no way to shut him up. For a moment, I thought I would have to take him to the emergency room. When he finally calmed down, he called me a matchmaker, a pimp, and worst of all, a liar and a manipulator. He couldn't believe that I would throw him between my friend's legs and behind her. His final conclusion was that I was just messing with him. However, to see what would happen, he put me in charge of the planning, but he had one condition: "You have to tell Sonia that I'm a particular kind of guy, one of those who likes to be in charge and have the girl at his disposal." I was intrigued by the fact that he denied it and then accepted it with that strange condition. Something was on his mind, and I couldn't figure it out. The next night, I told him what I had planned. Sonia would come to our house for lunch on Saturday, taking advantage of the fact that our parents would be out of town for the weekend. Lunch would be a way to break the ice and create a comfortable atmosphere for her. Then, I would leave with the excuse of going to the beach with my friends, and I would sneak up to Alex's room through the back stairs and hide in the closet, where I could see everything through the slatted door. Sonia arrived at 1: 00 PM, dressed in all black with a tight top, mini skirt, and sandals. I also got dressed up, but Alex was as casual as ever, in his swim trunks and flip-flops. I didn't think his outfit was appropriate. Sure, he didn't need to seduce her because she knew what she was there for, but still, he could have made a better impression. I realized that this hadn't crossed his mind when he made his move. "Sonia, tell me something, " Alex said, and we both listened. "Are you as much of a slut as Laura? " he asked as he stuck his bare foot between her legs under the table. Sonia jumped in her seat and noticed it. "I don't understand what you mean, " she replied, trying to hold her ground. Alex pushed his big toe into her pussy, and Sonia jumped again. "I mean, do you like sex as much as Laura does? " "I wouldn't know because I don't have that information, " Sonia murmured, holding her breath as she felt Alex's finger between her pussy lips. "Do you get wet if a guy does stuff to you? " Alex asked again. "If I like what he does, like any other girl, " she murmured. Her vague response and the blush on her cheeks indicated that she had indeed gotten wet. Alex confirmed that his finger had also felt it. Seeing my friend in a tight spot, I asked Alex to help me clear the table and come to the kitchen with me. "If you keep teasing her like this, she's likely to get embarrassed and leave, " I said, questioning him. "Why would she do that? " he asked, indifferent. "She knows what she's here for, and I want to find out how into it she is." We agreed that he would stop teasing her for the rest of the meal, and I would leave them alone afterwards. After lunch, with coffee on the table, Alex said he wanted to have it in the garden. Shocked, we watched as he took off his swim trunks and left them on the back of the chair, picked up his mug, and walked away like it was no big deal. I looked at him with eyes that said "What the fuck are you doing? " but he didn't care and kept walking. Then I suspected that he was up to something. Sonia went out to the garden with Alex ten minutes later, and she sat on a lounge chair next to the one he was using. I watched them from the window of Alex's room. "Let's get one thing straight, " Alex said. "You know why you're here, right? " "Of course, " Sonia replied, looking him in the eyes and then looking at his crotch. "Laura said you were, too." "And she told you that I'm a little peculiar, right? " Sonia nodded, and Alex continued. "I don't want you to think I'm a macho, it's just that I like to know how motivated the girls I have sex with are." Sonia kept looking at his cock and licked her lips when she heard the word "sex." Alex got up from the lounge chair and sat on the edge of hers, facing her. He put his hand between her legs and rubbed several fingers over her panties. "I like girls whose pussies are very tight, " he whispered in her ear. "It's a pleasurable challenge to open them and find out what they're hiding, " he added, putting his index and middle fingers inside her vagina. Sonia moaned a couple of times and bit her lip as Alex fingered her. "Help me take off my top, " she begged, trying to catch her breath. "It has a zipper, and it's hard for me to do it myself." Alex only agreed to lower the zipper, and then he watched as Sonia took off her top like a professional stripper, making Alex even more excited. Then he saw her small, perky breasts, and her hard, pointed nipples looked even more appetizing than before. "Now take off your panties, " he ordered, "and walk very slowly to the corner where the grill is, and stop there without turning around. I want to see you shake your ass while you do it." Alex wanted to make me suffer with uncertainty about what was happening, since I couldn't see that part of the garden from where I was. Alex went to Sonia when she stopped, pressed his hard cock against her ass, and put his hands on her breasts. "I bet many guys have told you that you have a spectacular ass, " he whispered in her ear as he pinched her nipples. "I don't remember how many times they've said it, " she replied between moans. "But now, the only thing that matters is that you think so." Alex had to flex his knees a little to put his cock between her thighs. She moaned when she felt it rubbing against her pussy. "My sister says you like anal sex, " he whispered in her ear. "She didn't tell you a secret, I hope." "I like it a lot, and it's common knowledge among the people who interest me, " she replied between moans. "It would be a secret if we weren't in this situation." Alex was surprised by Sonia's boldness and willingness, but he still needed proof. "Come with me, " he said, taking her hand, and together they went inside the house. I waited by the door of Alex's room, but they took too long to come up. I walked down the hall on tiptoes and reached the balcony at the end of the stairs. The two of them were standing next to the dining table, hugging and making out with each other. They stopped kissing, and Alex forced her to bend over the table with her back and stomach on it, her legs on the floor, and her ass in the air. I was surprised that Alex asked if she had any objections to doing it without a condom. She shook her head and said that she only had unprotected sex with a few guys in her crew that she trusted completely. Alex was so into it that he was already fucking her pussy before she finished explaining. But then he suddenly stopped and watched her as she moved back and forth, more and more insistently, moaning like a bitch in heat. Alex knew then that she was serious and would do whatever he wanted. He got up, opened the drawer with the napkins, took one, rolled it diagonally, and said: "I'm dying to try your spectacular ass, and I'm going to blindfold you. I want to deprive you of your sight so you can focus on what's important. Is that okay with you? " Sonia took a few deep breaths and agreed, whispering repeated "yeses" in a tone that was so exciting that it was hard to believe it was real. Alex put the tip of his cock in her ass and slowly started fucking her. She didn't complain or make a sound of protest, even when he started fucking her harder. "I see that your ass has been opened up quite a bit, " he said as he fucked her. "It seems that Laura was right." "About what? " Sonia asked between moans. "She said that not only do you like anal sex, but you're also a total slut." Sonia giggled and responded openly and without shame. "Since they opened it up for me, about three years ago, I have to admit that I like it more than regular sex." "That's good and good for both of us, " Alex said, smiling from ear to ear. "I'm in the mood today, we have plenty of time, and I plan to fuck your ass until one of us says enough. But first, I want to watch you like this from the armchair." Alex surprised me by not sitting in the armchair, but by taking off his shoes and sneaking up the stairs. He must have suspected that I was spying on them, because he never looked towards my position. He found me behind the corner of the hallway, turned me around, and bent me over with my ass in the air. He lifted my skirt, pulled my panties down a few inches, and ordered me not to make a sound as he fucked my asshole. I didn't say a word, I was surprised and fascinated, sighing softly as he fucked me. "Sonia's ass is a miracle, but I wouldn't trade yours for anything, not even hers, " he whispered, covering my mouth so I couldn't answer him. "I plan to take turns fucking both of you until I'm tired." Now I understood why he had blindfolded the other one. It was a surprise for me, and I enjoyed it for a few minutes. Then he went back to Sonia and started fucking her ass again. She screamed when she felt him inside her unexpectedly. Then she moaned with pleasure as he fucked her. The scene was brutal, and I couldn't help but touch myself. I took off my panties, opened my legs, and started rubbing my clit with my fingers. I didn't take long to have an orgasm, and I felt my pussy juices running down the inside of my thighs. I looked at the others, and Alex was fucking Sonia's pussy. She didn't take long to cum either, moaning like a crazy person as she shook her hair. Both of them were sweating like pigs, and Alex suggested that they take a break to cool off. He told Sonia where the bathroom on the first floor was, and he went to the one on the second floor, saying that he had a special towel for his delicate skin. I had to cover my mouth to stifle my laughter, amazed by such an excuse. Anyway, Alex asked Alexa to play a music playlist, went back upstairs, took my hand, and dragged me to his room. He pushed me onto the bed on my stomach and stretched me out completely. "I don't know where you get all this energy, " I said as he sat on my thighs and started fucking my ass again. "I jerked off around 11: 00 AM, " he confessed as he fucked me. "It's an experiment to last longer, and it seems to be working." And work it did. He kept fucking me and going at it, but just when I was about to cum, that bitch of my friend had to interrupt us. "Be right back, " he said, hearing Sonia call him, and he rushed out. I rolled over on the bed, opened my legs, and had to console myself with my hand again. When I went back to the balcony, I heard Sonia moaning, but I couldn't see either of them. I listened more carefully and found them right below me. Alex had put the armchair there, and Sonia was kneeling on the seat, leaning on the backrest. As for Alex, he was behind her, fucking her hard. I had a clear view of his cock going in and out of her ass. I thought Alex had set it up this way on purpose so I could see it all. Sonia's face was out of my view, but I could only imagine the expression on it based on the little cries she was making. "I only need a double penetration to make this afternoon perfect, " she said, panting with pleasure. "Don't tell me you're into that, too, " Alex said, looking up at me, locking his eyes with mine. For some reason, I got jealous, suspecting where this conversation would lead. Sonia answered like it was nothing. "Every now and then. My friends don't last as long as you, so I turn to two of them when I'm really into it, like I am now." Alex slowed down his thrusts, seemingly very interested in the topic, just as I had feared. "Maybe we can set up a threesome with one of those friends sometime, " he said, not taking his eyes off me. Sonia laughed and said in a slutty tone: "Too bad we can't go back in time, because now there's no way. But hey, if it's you two and him, I'd be all for it." At this point in the story, I couldn't decide if Alex was the biggest asshole in the world or if Sonia was the biggest slut. She had kept this perversion well-hidden. But it got me thinking. I've never done a threesome before, and maybe it's time to give it a try. Sonia's screams announcing that she was cumming brought me back to reality. Alex filled her ass with cum not long after. I knew I had started this whole thing, but I had seen and heard enough. I ran to my room, took my phone, and called my brother. He took a while to answer because he had left his phone on the dining table. "Tell that bitch to fuck off, " I said, pissed off. "Tell her that I'm stuck with my car and you have to pick me up." Alex reluctantly followed my orders, got dressed, and saw Sonia off at the door. He said he would be a while because he had to get the car out of the garage. "What the fuck was that about, saying you want to fuck Sonia with two or three guys? " I asked when he came back. "It was just something I said, " he replied, shrug "Well, I hope it's true, " I said, calming down a bit. "Because I have a feeling that before you fuck her with someone else, or with others, I'd rather you think of someone who might like me, but who doesn't know we're siblings. You know what, Alex? I've got this crazy urge to try a threesome." Alex laughed in my face, but he agreed to give me what I wanted.