My sister's boyfriend makes me his slut Pt1

Good today I'll tell how my sister's boyfriend did what he wanted with me, I'm not very good at narrating but it excites me to tell this so I'll bring relatable stories about everything that's happening in my house. It all started when my sister brought a guy home, they had known each other for years from the academy where they used to attend together and during the pandemic they became really close and ended up being a couple, I had only heard some descriptions from my sister until then but never seen him in person, he's a tall guy 1.71 with black hair and eyes, the thing is that my sister would bring him home more often and sometimes they'd find each other hiding to kiss because my parents are pretty strict, one day after getting back from school early due to a teacher's absence I entered the house without making much noise just wanting to rest but when I finished climbing the stairs I noticed the door to my sister's room was slightly open so I approached to talk to her but before I could say or do anything I saw through the small opening that my sister was naked, which surprised me and made me step back, tried to go to my room but couldn't help feeling curious so I cautiously went back to see what was happening, I noticed my sister was arched and naked while her boyfriend was sitting on the edge of the bed, after a few seconds I realized she was sucking his dick while he was holding her hair and telling her things like: come on slut please your master, I like you being a submissive slut etc. that really got me off especially when my sister got down on all fours and let me see her holes, it's not that I'm incestuous but my sister has a good body, after observing for a bit Cris picked up my sister and started masturbating her roughly with one hand while holding her hair with the other neck, my sister's moans and her pleas to be fucked caught me more by what I could get used to and I put my hand in my pants to start touching myself while watching them because he had put on a condom and told my sister to open her vagina for him, the way he was dominating her and she was obeying him sumissly made me excited every time, I was in the front row watching Cris's penis pumping into my sister and she was moaning like a slut, he kept insulting and degrading my sister with words like: you're my dirty slut, I'm going to break your vagina slut, I love it when my toy tightens her vagina for me or soon you'll be nothing but a semen deposit, and every word he said made me get more and more excited until by mistake while I was masturbating I kicked something with my foot and made some noise, so they stopped instantaneously and my sister told Cris to check what happened, I got up as quietly as possible and ran to my room and hid under my bed, my heart was racing a thousand beats while listening to Cris and my sister's footsteps until they came to my room and I could hear what they were saying. Kia: do you think my sister could have seen us? Cris: I don't think so, she must still be in the U, we should just keep doing what we're doing Kia: but if my sister comes back we might get caught and that would be a problem Cris: calm down slutty, nobody will find out your secret, nobody will know you're my sexual toy Kia: okay it's fine let's go back to my room Cris: no, I want to do it here Kia: you're crazy, this is my sister's room, we can't be here Cris: of course we can slut, it'll be quick so lean against her bed and open your vagina or do you want a punishment Kia: no, no punishment, it's fine let's do it but quickly vi how my sister's feet were in front of my bed and then Cris's behind her to not waste time and go back to fucking like animals, now in place of excitement felt fear if they discovered I was under the bed wanted to know how I would get out of this situation but it was hard to think with all the noise they were making could see the movement of their feet and how my sister was holding off Cris's advances while she moaned at the same time that every now and then you could hear slaps, after a few minutes I finally heard them arrive at orgasm and then saw how Cris separated from my sister leaving some drops of semen on the floor. Cris: You were fabulous slut Kia: thank you papi equally your cock was delicious Cris: I love that you're a slut so perverted Kia: and I love that you're the one who makes me like this Cris: now I want to do a few more things but in your room so let's go slut Kia: yes, but first let me clean this referring to the semen drops Cris: leave it the slut of your sister she won't notice better come and obey me Kia: okay papi Cris: walk on all fours to your room Kia: yes my lord my sister got down on all fours and left with Cris from my room before they went I could see how the condom was hanging from my sister's vagina, which was dripping with Cris's semen once they were gone I came out from under my bed and felt like my chest was finally calming down a bit I was in a mix of fear and excitement but the excitement was greater since I had never had a sexual approach and this had been a live class me got up and went carefully to where the semen drops were and by morbo and excitement I approached to smell them they didn't smell very well but their smell was so penetrating that I felt it had reached the deep part of my brain causing me to get even more excited and without thinking I stuck out my tongue and licked it it didn't have a good taste either but if it served for my vagina to feel hotter so I couldn't resist anymore I took off my pants and saw my vagina was all wet but I didn't care and I I started to masturbate thinking that the place where my sister was with Cris, who made her his slut, was mine. I imagined how it would be to feel all her passion in my vagina, how it would be to be treated like he did with my sister, and while I lost myself in my thoughts, they became dirtier until I imagined my sister and me being the whores of Cris and with that thought I reached a small orgasm. After that, I felt like I could and with my legs still trembling, I snuck away to see if they had noticed my presence in the house, luckily they were so focused on getting it on that they didn't notice, so I took advantage and left the house silently to go to a nearby park. I waited around 10 minutes before going back to the house this time making noise on purpose and slowly climbing the stairs. When I got upstairs, I saw them sitting in the living room chatting. Kia: Hi Mia, how was your day at school? Cris: Hi Mia, Mia: Hi Kia and Cris, fine but a bit tired. Cris: Sure thing, don't worry about it, go to your room and rest. Mia: Thanks Cris, see you later. I went to my room and didn't fall asleep but instead stayed fantasizing about what had happened that day. Later, almost a week had to pass before I saw Cris again but everything changed that day. When I finally saw him again, it was because my sister invited him to a family lunch. That day she had gone out to do some things while I helped my mom prepare the meal when suddenly he arrived. My mom told me to take him to the living room and we could chat while she finished up. I said it was fine and went downstairs to open the door, then greeted and came back upstairs with Cris who headed to the kitchen to greet my mom and later came back with me to sit in the living room and watch TV. Mia: What do you want? Cris: Whatever Mia: Sure? I started looking for something to watch next to him trying not to seem nervous since from the day I had found them having sex, I had felt a bit uncomfortable being alone with him but in that moment I'm getting close and placing my hand on your thigh quite near my groin Mia: What's going on, Chris? He came up to my ear and told me Chris: I know you saw me having sex with your sister the other time. Did you enjoy the show? At that moment, I felt like I was tensing up and getting pale at the same time as if I was about to faint. They had discovered me Mia: I...I didn't...want to stutter without knowing what to say Chris: Note when you peeked through the door to see what we were doing and also note that you were masturbating while watching us, what a pervert you turned out to be Mia: I still didn't know what to say or respond to what he was saying since my mind had gone into panic mode and he knew how to take advantage of it Chris: You know, Mia, you're also very pretty. He said as he raised his hand to my groin and started caressing me over my clothes Chris: Relax, just let yourself go and you'll feel the same way your sister does Mia: Wait...my mom before I could keep arguing something the met his hand inside my pants and started masturbating me directly. That's where my willpower broke since I had been imagining him taking me for days. I knew he was in love with my sister but I couldn't resist him, well said, I didn't want to Chris: Good girl, let yourself go Chris was manhandling me and giving me little kisses on the cheek until suddenly stopping when I was already feeling very good Mia: Why did you stop? Chris: We'll continue later. He stopped and left me quite heated as he walked away, watching him take his fingers that had masturbated me into his mouth Chris: Ma'am needs help with something. That was the start of my downfall, for now I'll leave this story here and continue it soon so don't worry.