ObsASSed

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Slow developing story: how I got obsessed w. my sister's ass.
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Hi.

My name is David.

This is a story about me and my sister Katie. It basically starts shortly after Katie's eighteenth birthday. I was 26 at the time. I am eight and a half years older than her. At the time when our fraternal relationship started to get a bit strange, I was still living at home. I was in the process of writing my doctoral dissertation. I was working at the university, but I couldn't really afford my own place. Plus, I actually liked living at home.

I always had a great relationship with my parents... and especially with Katie. I think the age difference really helped a lot... I always felt like a big brother who needed to protect her. I babysat her. I did everything for her. I don't know... It's really difficult to sum up about 6500 days together in one or two paragraphs to explain what our relationship was like, when we grew up...

We always had a special bond. We liked hanging out together... spending time together... I don't know... it's weird... looking back, I don't think that there was ever any period of time, where either of us was embarrassed to be seen with the other... or any BS like that... like most teenagers. I remember a time when we both stayed home on Saturday night, to watch a movie together... even if there was a party or something. Sometimes we went to the same parties. Of course that doesn't mean that we hung out with each other 24/7... We did stuff alone as well... but when we did stuff together, we always had a great time...

:--

Saturday, August 18, 2018

...and our friends definitely noticed our special bond as well. I remember Katie's eighteenth birthday party back at our house... She just turned 18 two days earlier. Mom and dad were gone for the weekend.. they did that once a month... go away for two or three days to stay at a nice golf resort and play golf all weekend... or something like that... they still do actually.

Well... back to the party...

There were like ten or twelve eighteen-year-olds in our living room. I decided not to join them, even if Katie had asked me to... but... I don't know... I didn't wanna disrupt the party she was having with her classmates... besides... I didn't really like some of the boys in her class. Like I said, I was 26 at the time, and some of those 18 year old boys were just really dumb and immature. So I stayed in my room for the most part.

We live in Europe, so everybody at the party was allowed to drink alcohol. Mom and dad knew that as well and asked me to keep an eye on them. I knew Katie was smart and knew her limits... but I didn't know the other kids all that well.. and I definitely didn't wanna clean up some kids vomit... so I visited the kitchen like every 50 minutes or so to get myself something to eat or drink, but really just to check up on them.

At about 1 a.m. I decided to go to the kitchen again. During my last checkup at midnight, I saw that everything was pretty much okay. There was music and dancing and alcohol... it was pretty dark in the living room... but everything was okay. Mom and dad told Katie that her friends had to leave at 2, but later they told me, that, if everything was okay and everybody was behaving properly, I could let them stay until 3.

So.. when I walked downstairs -- a few minutes before 1 -- I headed straight for the kitchen. From a certain spot in there, there was a straight line of sight to glance into the living room inconspicuously. But this time... I didn't even get that far...

Suddenly I heard my sisters voice.

"Oh David, thank god..."

Katie came running towards me. She was barefoot. She wore a tight black pair of jeans and a cute tank top. A strand of her brunette hair had fallen in her face. She had gotten a new hair cut that week to look pretty on her birthday. It used to go down to her shoulders and beyond that.. now it stopped at her chin. It actually looked pretty good.

"I need your help..."

She grabbed my wrist, turned around, walked away and dragged me with her.

I had a bad feeling. But I was kind of surprised that I wasn't dragged into the living room. I was dragged into the hallway.

"What are we doing?"

Katie didn't answer me, so I just followed her.

Then she stuck her head out and shouted into the living room: "I pick David!"

Two or three seconds passed..

"Hey. No way. That's not fair!"

That was Ashley's voice...

I still had a bad feeling.

"You said I can pick any guy I want. It's MY birthday. So I'm picking David!"

Katie was still grabbing my wrist. Now she turned around and faced me. I guess I must have had a terrified look on my face, because she said: "Do you trust me?"

I could only nod and then Katie opened the door of the closet in front of us.

"Get in."

I looked at her.

"What? No."

"Please!"

Katie let go of my hand and put both her hands on my hip and shoved me into the closet. It usually was pretty jam-packed. I guess somebody took some precautions...

Once I was in.. Katie stepped one foot into the closet, turned around and yelled into the living room.

"Okay. Go!"

Then she stepped into the closet and closed the door behind her.

I was completely shell-shocked. Suddenly it was completely dark. Katie was standing in front of me. She really had to squeeze in. It was a tight little closet.

"What is this Katie? Have you lost your mind?"

"I'm so sorry, David. We were playing a truth-or-dare.. spin-the-bottle... type game... It was Becca's idea to add 7 minutes in heaven... She's in love with Chris.. she tried to find something that would help her... and then I..."

"Katie... what the hell...?"

"I know. I'm really sorry. I didn't wanna drag you into this... literally... but... I panicked.. I didn't want to go in here with any of the boys out there. Maybe let one of them grope me...."

I thought about it. It actually was a pretty responsible move on her part. Of course I didn't want any boy to grope my little sister as well. And she knew she was safe with me.

"I'm so glad you came down..."

I still hadn't really said anything. I had no idea what to think. It was a very weird situation. It was completely dark. And Katie and I were squeezed together. I felt her breasts touch my upper body. And... I hadn't really realized it until that point.. I had my fingers on Katie's hips. I wasn't really holding her.. but I was sort of letting my fingers rest on her hipbone. I couldn't really put my hands anywhere else. It was just too tight in there.

"Did you ever do the 7 minutes in heaven?"

"Once or twice, I guess. When I was younger."

"What did you do?"

"Well... the first time, we kissed a little bit... I was fourteen or fifteen."

"So you just kissed?"

"Well... the second time I felt her up a little bit. Touched her breasts... you know... I was about your age."

"Well.. I definitely don't wanna kiss any of the boys out there. And none of them is allowed to touch my titties. That's for sure."

I couldn't see her face, because of the darkness, but I knew she was smiling.

"That's good. Well... I'm glad I came down then... I will try to protect you and your titties."

We both giggled.

"So you're not mad at me?"

"Of course not. "

"Okay. Good. 'Cause otherwise I would have let you feel me up to compensate you for all your trouble."

This time I wasn't sure wether she was kidding or not.

"Oh yeah? So I'm allowed to touch your breasts then?"

"Always."

After that it was completely quiet inside the closet. All that talk about tits made me focus on hers... and the fact that they were still touching my chest. And they felt surprisingly good...

Suddenly there was a knock on the door.

"Time's up!"

Katie opened the closet door and we both stepped out.

Ashley was standing right there with a huge smile on her face.

I didn't say anything and went into the kitchen. I hoped that neither Ashley nor Katie saw that there was a small bulge in my pants. I mean, I wasn't hard.. but my dick definitely stirred a bit. Fuck.

When I walked away I heard Ashley's voice: "So... what did you do?"

"We made out, of course."

Katie's voice sounded totally serious.

"What? Really?"

That was a male voice from within the living room. Well, actually it might have been two or three male voices speaking at the same time.

I don't know if they actually believed that Katie just made out with her brother, but I know she can be pretty convincing.

"Of course... What do you think?" she said.

I laughed.

Katie was so good at that. Messing with these boys. We both were. We had so much fun messing around... teasing guys.

:--

Saturday, September 15, 2018

I remember another party at some guys house. There were about forty or fifty teenagers there. The entire house was full. I didn't really go... I just agreed to pick Katie up and get her home. We arranged that I would pick her up at 1.a.m., but I was a bit early getting there. That day mom and dad told Katie that she wasn't allowed to drink alcohol, because she had like an important test or something on Monday. So when I walked into the house, I tried to squeeze through the crowd. I took a quick glance into the living room, but I didn't see Katie. So I headed to the kitchen. There were about seven or eight people in there. Katie was there as well. She didn't really see me and she was clearly not expecting me that early, because as I watched her, she was drinking a jello shot.

As she was putting the little plastic cup down on the sink, she looked up and saw me. She instantly froze. She was looking directly at me. I saw she had the tiniest smile on her face. Her friends all spun around to see what she was looking at.

"Oops. Busted."

I guess they all thought she was being serious, because nobody moved or said anything.

"I'm not supposed to drink these..."

Katie put the cup on the sink... and then grabbed another one... and drank it.

A grin appeared on her face. I had a grin on mine as well. I didn't really care. So she had a drink or two... I definitely wasn't going to rat her out and she knew it.

"I guess I was a bad girl. Great... That means that my brother is going spank me again, when we get home."

I almost burst out laughing. Of course, I had never spanked her... So I tried, as best as I could, not to laugh and stay serious.

The crazy thing was, nobody said anything. All the boys there just stared at me.

:--

Tuesday, October 2, 2018

That little tease became like a running gag between us. A few weeks later I was driving home from the supermarket in dad's car. It was about 2 p.m. on a Tuesday. Like I said, I was working on my dissertation at that time, which meant, I had a lot of free time. I went to the university just sporadically. I was home most of the time. So... anyway... I was driving home and all of a sudden I saw Katie and Rebecca. They were sitting on a bench giggling. So I stopped the car and rolled the window down.

"Hello girls. Aren't you supposed to be in school right now?"

"We're skipping PE," said Rebecca.

"Oh yeah?"

"We're on our period." Katie had a huge smile on her face.

"Both of you? Simultaneously?"

"Yeah. What a coincidence, right?"

Katie was laughing.

"Come on. Get in. Class should be over soon anyway. We'll drive around a bit and then I will bring you guys home."

Both of them jumped in behind me, so I started driving.

"You know... it's not smart to skip school... to skip classes.. even PE."

"Oh, come on. Don't be such a fuddy duddy," was Katie's response.

"Fuddy duddy?"

"Not everybody can be such a smartypants like you," ...she was definitely in a good mood...

"Smartypants?"

I looked in the rear view mirror. Katie had a huge grin on her face.

"Someone's a little sassy today. You know what will happen to sassy girls, right?"

We looked at each other in the rear view mirror.

Her smile was gone, now it was more like an impish grin.

"They're getting spanked?"

"That's right."

I broke the eye contact and focused on the road.

"Are you really spanking your sister, David?"

"What do you think? If she's misbehaving... I'm her big brother... What am I supposed to do?"

It was so hard to say that in a serious tone. I don't know how Katie always kept a straight face during things like that....

"And you are okay with that?" Rebecca was turning to Katie now.

"Well... he's my big brother... he just wants me to act right. So yeah.. when I deserve it... I just wanna make him proud..."

Of course, I didn't spank her when we came home, and I didn't tell mom and dad either. But that spanking bit, like I said, became like a running gag between us.

:--

Saturday, October 6, 2018

On the following Saturday, mom and dad were away on one of their golf trips, Rebecca slept over at our place.

For the most part, I didn't even see them during the day. At night, they were watching TV downstairs in the living room. I was up in my room, working on my dissertation. I know... amazing activity for a Saturday night... Anyway... when I went downstairs into the kitchen to get a glass of juice, I saw that the living room was pretty dark. The only light came from the TV.

I switched on the light in the kitchen, which resulted in an "Oh fuck" scream from the living room.

"David? Is that you?"

"Of course. Who else should it be!?"

"Get in here."

I put the class on the counter, switched off the light and walked into the living room.

"You gave me a fucking heart attack."

"I didn't do anything!"

"We're watching Saw."

"YOU'RE watching a horror movie?"

"I know. It was a bad idea. I'm so fucking scared."

Rebecca was laughing.

The girls had it pretty cozy there in the living room. Katie had put a bunch of blankets on the floor. She was sitting on the floor, her head and back leaned against the foot of the couch. She was wearing a shirt and a black panty -- hugging a pillow.

Rebecca was lying on the second couch. She too was wearing just a shirt and a red panty. She was lying on her side, half-covered under a blanket. Her left leg was under the blanket, her right leg was clearly visible, even in the dark.

It wasn't anything unusual... Like Katie, Rebecca grew up around me. I have seen her in her underwear, pajamas or bathing suits. Like Katie, she felt comfortable around me, I guess.

"So, which part are you watching?"

"The first one."

"Oh. I see. That's the best of all of them anyway."

Katie was still hugging the pillow and had her head slightly turned away from the screen.

"Can you please stay here, David."

"Oh come on, really? Just watch something else, if you're too scared."

"Pleeeease!"

"And we're not watching something else. I wanna see the end. I've heard it is worth watching," Rebecca said.

"Well... it actually is," I agreed.

"Okay... so... please," Katie begged me.

"Alright."

I walked into the living room and sat down on the couch next to my sister.

"What are you doing?"

"Ha?"

"Come down here. You have to protect me!"

I laughed out loud. This was ridiculous. But I didn't want to argue with her. Besides, I hadn't seen the movie in a long time, so I figured, what the hell...

I stood up, and sat down on the blanket next to Katie. She immediately scooped closer. She threw the pillow away, grabbed my right arm, hugging it, and placed her head on my shoulder.

After a while Rebecca looked over to us.

"I wish I had a brother like him."

I smiled.

"Well... you can't have him. He's mine."

Katie laughed and hugged me even tighter.

We sat there like that for a couple of minutes. Then on the screen someone had to saw one of his own limbs off to escape the crazy killer... and all of a sudden Katie squeaked. She turned over to me, grabbed my arm even tighter and buried her face in her hands and on my chest.

"I can't watch..."

By her scooping closer, my hand inadvertently landed on Katie's butt. She didn't say anything, she just turned to the screen, opened her hands a little bit and tried to watch the movie through her fingers.

"Oh my god... how are you..."

She turned to the other couch and, I guess, wanted to ask Rebecca why she wasn't squeaking. She then turned back to me.

"Look..."

Katie smiled. I looked over to the other couch, and then I saw that Rebecca was sleeping.

Katie sat up, so I took my hand away from her butt. She kept watching the movie.

"Can you maybe stay here, until I fall asleep, too!?"

"Yeah, sure."

"Thanks."

Katie then took a small pillow and placed it on my lap. And then she lay her head down on the pillow.

"This is such a scary movie."

I didn't respond.

A couple of seconds later Katie lifted her head and looked over to the other couch. I didn't know what she was up to. Then she grabbed one of the blankets and put it over both our bodies. After that, she lay back down. Another couple of seconds passed and then she whispered:

"Can you maybe put your hand back where it was before. It felt really good and I'd feel safer and more comfortable."

I hesitated for a few seconds.

"There?"

I lay my hand back on her butt.

"Yes."

We stayed like that for a while, watching the movie. I basically had the side of my hand on her butt, so it wasn't like I really felt it. But now the movie was getting more and more intense, and I felt that Katie was getting anxious. So I turned my hand over and lay my palm over her butt cheek. I started to pat it softly and then began to stroke her cheek carefully.

"That feels really good. I will fall asleep in no time, if you keep doing that."

I didn't say anything. I just continued to pat and stroke her butt.

After two or three minutes I heard that Katie's breathing was getting more even and a bit heavier. I couldn't really see her eyes, but I kind of knew that she was asleep.

So I just sat there and watched the movie all by myself.

But after another two or three minutes, I saw out of the corner of my eyes, that Rebecca was moving. I glanced over and saw that she turned over. She was lying on her side again, but now she was facing away from us.

And somehow, by moving over, her panty slid between her butt cheeks. Now it looked like she was wearing a string panty. Now... I'm not a jerk... I would never hook up with one of Katie's friends or try anything with any of them... but... I'm only a guy. And her butt looked really amazing. The way she cuddled with the blanket, it almost looked like she was naked. You couldn't even see her underwear anymore.

Fuck.

And purely as a reflex, my fingers flinched and I inadvertently grabbed Katie's butt, like my fingers wanted to grab Rebecca's butt.

"What now? Is the guy dead?"

Oh shit. Katie felt it. I panicked.

"Um... yeah.. it was really scary."

I was hoping she had her eyes closed.

"Sorry," I said.

"Don't worry. I liked it. But you woke me up. You have to make it up to my butt, by being a bit gentler again."

Katie fell asleep shortly after. It was a good thing that there was a pillow between her head and my lap, because I just sat there in the dark, constantly trying not to look at Rebecca's ass, while my fingers were stroking Katie's butt... Needless to say my dick really liked the situation... I couldn't help it...

:--

Monday, October 22, 2018

Two weeks later on a Monday, there was a bad weather forecast. They said that it would rain pretty heavily throughout the day. So I told Katie that morning, that I would pick her up from school, if the weather was really that bad.

And it really was pretty bad during the morning, but at two, the rain stopped. I decided to pick Katie up from school anyway. I drove there and I didn't really see her at first. But then, I spotted her. She and four of her friends were standing pretty close together. At first I couldn't really figure out what they were up to. I stayed in the car and watched them. And then I saw it... they were passing around a cigarette.