I was coming home from college after another day of classes. I came earlier that day because my professor didn’t show up for my English class. I opened the door and came in. I lived in a big house that I shared with my sister, Valentina. I had lived with my sister for five years since my parents had gone abroad. I must admit right away that my sister and I had started to have this strange closeness some months ago.

I could hear the sound of the shower running, and I guessed my sister was taking a shower. I thought about her big round tits, and I decided to pay her a visit, just that as I was getting closer, I heard some sounds. First, her moaning, but then I heard some kind of loud bang, over and over again. Was she having sex with anyone else? I could not help but peek, and what I saw was just shocking. She was there in the bathtub on top of my cousin Ronald. His big cock inside my sister's sweet pussy. I didn't know what to do. I was angry. Really mad. So mad that I decided to get into the bathroom.

“What the fuck are you guys doing?” They looked at me and immediately stopped.

“Oh my god!” that was all she could say.

“Cousin... man...” Even my cousin was speechless.

“I didn't know you were coming so soon,” muttered my sister.

“Yeah... My English class was canceled,” I replied. I looked at her, and she could tell how mad I was.

“Andrew... I...”

“Slut!” I shouted at her.

I walked away and went to my room. I didn't know what happened next between them because I was so furious that I decided to lock myself and play some loud music.

Twenty minutes later, she knocked on my door. I opened it, and there she was, wearing white panties and a pink top. I could tell she was not wearing a bra since her erect nipples stood out.

“I'm sorry! Ronald came, we had some coffee and talked, and then it just went out of control. I know I screwed up. Please... Forgive me,” my sister begged.

“You’re a fucking bitch. How come you ended up fucking him?”

“I told ya... It just went out of control. Please... Don't be mad at me,” she said.

“You're gonna pay for this if you really want me to forgive you.”

“I’ll do whatever it takes.”

“Are you sure?”

“Yes, I am,” she replied.

“Come here!”

I grabbed her waist and brought her closer to me. Her tits pressed my chest, and I got a glimpse at one of her juicy nipples. I rubbed it with my right index finger and immediately got a hard-on. She smiled and grabbed my cock tightly. It felt so good, but I had to remind myself she had just fucked my cousin.

“So, are you going to make me pay?” she asked softly with an evil smile in her face.

“Fuck yeah!”

I got behind her and grabbed her 34D natural boobs. I squeezed them and she moaned. I started to push her very slowly towards my bed, and once we were next to it, I took her arms and made her hands rest on my mattress while I bent her back forward. I took her panties down, knelt down, and got my face close to her ass. I grabbed her buttocks and made them bounce. It looked so sexy. I moved them sideways and directed my mouth towards her asshole. I started to lick it, trying to penetrate her hole with my tongue.

She shook and I could hear a deep hiss. I licked it several times and then started to introduce my index finger, little by little. I could tell how aroused she was. I continued introducing my finger deeper and deeper, and at the same time, I tried to lick her hole. Then I stopped. I told her not to move and walked towards my nightstand.

I opened the drawer and got my lube. I removed the lid, got some and put it around my hard cock. I looked at her and could see her hanging tits waiting for me. I got closer to her, put some lube on my fingers and rub it around her asshole.

“What are you doing?” she asked.

“This is my revenge, bitch. I'm going to fuck your ass! This is gonna be your first anal experience, one you'll never forget, fucking slut."

When I started having sex with Valentina some months ago, she had made it clear that she didn’t want to have anal sex. It seems that she had tried with an ex-boyfriend, but it had hurt so much that she had decided not to do it again. She did let me finger her ass, but that was it. However, things were going to change if she wanted me to forgive her.

“No... Please, it's going to hurt,” she begged.

“It's that or you will have to forget about me... I'll be gentle, I promise.”

“Oh gosh… Ok… Gentle!” she requested.

“Sure… Don't move!”

I put more lube on my right index finger and introduced it deep inside once again. This time, I went deeper, and again, I knew she was in ecstasy. I took my finger out, grabbed my dick and started to rub her hole, gently. I told her to bend more, and so she did. Then, I pushed my cock inside, slowly, very slowly. She moaned. I got to introduce my dick a little bit more, and more, until she groaned. I knew she was in pain.

“That's what you get for being such a whore.”

“Do it slowly, pleaseeeee,” my sister pleaded.

I waited a little bit and then pushed again. Half of my big hard cock was inside her ass. It seems that the toughest part had already come. My dick came out a little bit and then I pushed again. I repeated that movement three or four times and started to get deep into her asshole. Deeper and deeper until all my cock was inside.

“Are you Ok?” I asked.

“I think so. Just move slowly, please”.

I touched her tits and then I squeezed them. God if I enjoyed them. So big, so round, just like her ass. My hard dick moved inside her hole slowly, gently. I slammed her ass and pushed a little bit harder. She moaned. It felt so good to be inside that tight asshole.

Then, I started to rub her clit. I had totally forgotten about it, and when I did, she cried out loud. She was really enjoying it. I wanted to explode inside of her. I took her top off and kissed and licked her back, while she moved one of her hands towards my balls. She grabbed them and played with them gently. It felt so good.

I got a little tired so I told her to lie down on my bed. She did. She was lying face down, so I caressed her back and licked it, moving downwards until I reached her asshole again and inserted my tongue. Her hole was bigger now. I played a little bit with it and then put my cock inside one more time. I started to move faster and faster. she screamed, but this time it was one of pleasure. I grabbed her tits and rubbed her nipples again and again. She gasped, and I felt so good. I was about to come. I couldn't resist anymore.

“So, did you like to be fucked in the shower? Did you enjoy his cock?” I whispered in her ear while I slammed her ass.

“No, I only enjoy yours. Gimme more... More...Please... Fuck me more.”

“Do you like how I fuck your ass?”

“Yeah!”

I moved on top of her a couple of times more until I exploded. It felt so good I couldn't believe it. I rested my face on her shoulder for a minute while I got some strength back. When I did, I put my left hand in her pussy and began rubbing it, with my flaccid cock still in her ass. I moved my hand along her pussy slowly, and after a while I increased the pace until her thighs started to shake, and so I knew she was about to come. I sped up and she screamed louder and louder. A huge climax invaded her body. I took my dick out of her anus and kissed all her body, exploring every single piece of skin.

I was so happy about my revenge, and it seemed Valentina was full of joy too. She would never forget her first anal experience. I was certain about it.