Katherine is two years older than me and the best sister in the whole world. Katherine or as I have always called her Cat is a slender girl with long wavy blonde hair, a pert pixie face and full red lips. Cat studied Ballet and Dance since she was a child. She is kind, sweet, forgiving and dead sexy.

I am a horrible brother! All I want to do is fuck Cat and use her little body like a whore. Seeing her at our pool in her string bikini made my cock so hard. After school I always meet Cat at the dance school where she goes for lessons. There is just something wonderful about seeing ballerina students all sexy and sweaty. Cat thinks I have a crush on all the dancer girls and she is right! But it is her really I want.

Nancy Manners was having a Halloween Party and Cat told me I was invited and gave me an invitation. But she and her friends are all seniors while I am a sophomore. I told sis "no I won't attend" and left it at that, but keep the invitation.

In the last 12 months I started using a home gym system and had grown to 5'11" but I wear baggy shirts and pants that are in style. In school we wear oversized jeans to be cool; mine are 42 inch jeans and I have a 32 inch waist; but looking cool is important.

The night of Nancy's party I saw Cat in her Indian Princess outfit and got an instant boner. Sis wore a very, very short suede skirt and matching low cut vest that shows off the round tops of her tits. It left most of her long legs bare, her bare midriff was beautiful. Her sleek slender body was showcased by her costume. Her hair was in two pig tails with a Indian headband and a half-face mask. Cat left for the party and I just wanted to see her in the costume again. I went to my room and brought up my sister-whore-slut folder on my laptop. I had all these plans and nothing would ever work; I couldn't use a date rape drug and maybe kill sis by mistake, couldn't kidnap her, just couldn't hurt her.

It was about two hours after sis left an idea hit me. I would go to the party; in old jeans, t-shirt that both fit like a second skin, while wearing an old Halloween mask that covered half my face. I told mom and dad I was going to Phil's house and took my things in a small bag. I am really proud of my body looks now; the exercise coupled with a low fat, high protein diet had changed me. I changed my cloths behind the garage.

I walked to Nancy's house and the party was in full swinger. All the seniors were having a good time. I hung around and spotted my sister. She looked so hot in that Indian Princess outfit. I played it cool and stared at her, off to the side so it did not look like I was stalking her. I saw my sister smile at me a few times.

I heard Nancy's friend say "those guy's that play varsity football are so hot" and she was looking my way. I had gotten smiles from a few of the senior girls tonight including my sister.

I saw sis go downstairs and I followed. No one was around and I smiled at her, sis gave me a smile. We were alone as everyone else was outside enjoying the good weather and cool night air. Sis smiled again and I just walked up to her.

"I am Katherine" she smiled and offered her hand. I held her hand after the handshake smiling at her. Sis did not know it was me and was blushing. Something about her manner made me bolder than I should be, I knew she liked me romantically.

I leaned in and gave my sister a gentle, soft kiss on the lips that turned harder. I kissed her as if it was life and death crisis and for me it was. I might never kiss my sister again in my life. Cat returned the kiss and pressed her beautiful full lips to mine. I held the kiss as long as I could and then I reached and hugged her to me and kissed her again. She had her arms around my neck and was snuggling into me as we kissed. I felt the tip of her tongue against my lips and my tongue touched hers.

We kissed like lovers and she was returning every kiss with as much passion as me. I caressed her back as we kissed and her bare skin was like silk. Pulling Cat into my erection as we held each other, our mouths locked together. My hand held the back of her neck and the other hand roamed her silken back. I was bolder than I should have been and dipped one hand under skirt and grasped her toned butt cheek pulling her into me. Cat was wearing a thong and her sexy ass was nearly naked.

She responded by kissing her harder and my hand glided over her ass. It was firm, smooth and felt so nice. Cat moaned in my mouth as I explored her. She was rubbing her belly into mine as we kissed, grinding her pussy against my erection. Kissing her was better than I thought it could be. Her tongue was in my mouth, mine in hers. I reached up and pulled the shoulder strap of her vest down and off her shoulder, Cat's left breast exploded out of her costume and I cupped it lovingly as we kissed.

Cat nipple was hard in my palm as my hand squeezed her tit with each kiss for five minutes. Her breast felt like heaven. I had felt up her butt and had felt her tit when Cat took my hand and drew it down, up her skirt, then up her thigh and onto her mound. I was touching my big sister's pussy through her thin satin thong panties. I slide my hand down inside the waistband of her thong. I held her pussy in with my finger tips and ran a finger tip up her cunt lips. My lips fastened on her nipple and I sucked sis as I felt her cunt.

We must making out and kissing for 15 or 20 minutes when people started to run downstairs into the basement laughing and wet from a sudden rain we had not heard. My back was to the door and she had not been seen. Cat reacted fast, adjusted her clothing, covering her tit and pulled my hand from her groin with the first sounds. She looked up into my eye's and kissed me again.

As people flooded the basement I made a get away and I heard Cat call out "wait" as I fled into the crowd. I left the house and walked to home wet, in a pouring rain and changed in the garage. My parents did not even noticed I had been gone. I went to my room and laid there thinking of sis. I had kissed, felt Cat up, even kissed her nipple and touched her butt. I was in heaven.

The next morning over breakfast I heard her telling mom about this dreamy guy she meet and how he had disappeared. "He left and I know he wanted me for a girlfriend, I just felt it."

"Who is he then Cat" she asked?

"Either a football player at our school or one of their friends I think. A few of the girls recognized him from the beach."

I listened with great interest. She had liked our making out.

Later I heard Cat talking to her friend Marg on the telephone, saying "this guy is the one, I just feel it. He was so romantic. He kissed me like a dream and such a nice guy. He could have taken me into a side room and fuck me, but he respected me." I felt my heart drop, had I known that; I would have taken advantage of the knowledge and fucked her. Eavesdropping is wrong but I could not stop myself.

"Marg this guy was so in tune with me, I just felt so right with him. That first kiss sealed my heart. I have to have him in my life, I just feel so sick losing him before I even him. " Sister answered. " I know he loves me as much as I love him. No he is my heart, I just fell it" and she started to cry.

I watched my sister and her obsession with her masked lover and how down she looked. I felt guilty but could not tell her, I was ashamed about what I did. I had violated her.

I thought things would get better but Cat got worse and appeared depressed. I tried to cheer her up and made a mess of it by talking to her about it.

"Cat, you will find another guy, this was just some guy and you need to move on."

"Dan please you don't understand, you just couldn't. You're my brother but you're a Sophomore."

I thought yeah I am; but I am the guy that made out with you. "Cat your hurting yourself, this is not right this guy isn't good enough for you."

"Shut your face Dan you just can't see. You don't know him and he is good enough for anyone" she yelled at me.

"I know who he is and he just is not for you sis."

"Dan your such a lying shit I hate you. If you know him, help me to see him" she whined.

I just could tell my big sister that I had made out with her and I left her room. I had been masturbating thinking about kissing Cat ever since.

Cat seemed to get worse, she stayed in her room all evening, never came down and I heard mom telling dad she was worried "she might be depressed over being dumped by this boy."

I knew I had to act and went upstairs and knocked on my sister's door. "Go away" she called out and I entered. Cat looked sexy even in flannel pajamas.