Lacey was quickly approaching her 13th birthday. I swear I had never seen her so excited. I had taken a look at her birthday list, it was pretty standard fare. New clothes, a concert ticket, a purse. When the big day was finally here, she had a huge party with her friends.

Our parents didn't let her invite any boys (yeah, because it was the ones out there they had to worry about), though I don't think she would have wanted to any ways. While I had started paying more attention to Lacey, I was still at a loss when it came to her love life (outside of me of course). She was certainly attractive enough, but I never saw her flirt with, or even talk to any other boys.

I volunteered to babysit the party so that my parents could relax for a bit. Well, mainly so that I could hang around, but they didn't need to know that. There were 10 girls in all there. The youngest was 11, and the oldest 14. Other than my sister and the 14 year old, a pretty hot redhead with glasses, none of the girls really caught my attention. I seemed to have caught theirs though.

"Your brother is so hot." was a phrase I kept overhearing throughout the day.

Lacey, for her part, acted completely nonchalant about it. She would just shrug her shoulders, or respond with a whatever. I considered making them all jealous by giving her a deep kiss, but figured the jail time wasn't worth it. I settled for flirting a bit with the redhead instead. She tried to act cool about me talking to her, but couldn't really hide the excitement in her voice. Maybe I could sneak her upstairs?

As the thought ran through my mind I looked up and met eyes with Lacey. She quickly looked away and joked around with her friends. Immediately I felt a pang of guilt. I couldn't do that to her. She was my sister, it was her birthday, and while I wasn't completely sure, there was the chance she had some deep feelings for me.

The rest of the party remained pretty standard. The rents stopped by half way through to open presents though. When Lacey got to mine, she jumped up with joy and gave me a big hug (Must. Not. Grab. Sister's ass. In front. Of parents.). My job payed decently enough, so I got her the latest iPhone. Our parents were in on it and got her a nice case to go along with it.

The girls started filtering out around 9:00 PM. Our mom and dad had decided to stay at a hotel for the night, in case the girls wanted to sleepover. Fortunately for me, it seemed they weren't for it. As soon as the last girl left, I turned to my sister.

"Why aren't any of them spending the night?"

"We were planning to go to the aquarium tomorrow, so we just called it a night so that we could wake up early."

It didn't make much sense to me, but I wasn't going to say anything about it. This meant I had Lacey for my self tonight. I sat down on the couch pulling her to me into a deep kiss. The thoughts of the redhead came back and I felt another pang of guilt. I also started to wonder again, why my sister never seemed interested in a boy.

"Hey, Lacey. Could I ask you something?" I said, breaking the kiss.

"What is it?"

"Have you ever dated before?" I inquired, trying to hide my anxiety.

"No, well... No"

"O... Kay." She seemed to be holding back some info, but I decided not to push that part. "Well, have you ever flirted with, or even been interested in any other guy?"

"No." A quick short answer from her.

"Oh? Girls?" I asked finding my thoughts going back to the redhead. Maybe her and Lacey would be interested in having some fun. My penis gave a small twitch in approval.

"No." Damn, well that at least gives me another command experiment to try some day.

"Well, do you enjoy what we do? I'm not forcing you here, am I?" I was getting worried. She had obeyed everything I told her to do, but she never went out of her way to start it. I couldn't bare the thought of forcing Lacey into something she never wanted.

"I enjoy it. It's nice." Well, nice probably wasn't how most would describe it, but I certainly didn't mind the answer. With my curiosity and anxiety satiated, I decided to move on to my lust.

"Alright, well, you're the birthday girl. Is there any special you want to do?" I didn't think she would ask for anything sexual. Lacey usually just went along with it. I figured she would pick out a movie, or maybe some video games. The answer I got caught me by surprise.

"Umm, well." She started to look away nervously. "Could we, um, I wanted you to lick me again."

She was practically tripping over the words trying to get the sentence out. After the initial surprise though, I became delighted. We got up and headed to my room. Lacey lied down on the bed. She was at this point, still in her party clothes. A black t-shirt, with "Birthday Girl" written in fancy pink font, and a blue denim mini skirt. After a quick kiss I moved down and started to lift her skirt.

"No, wait" Lacey shouted really quickly.

"What, what's wrong?" I half shouted and half whispered. I jumped up, taking a quick look around.

"Nothing, it's just that... I want us to do it together." She sounded extremely nervous when she said it.

It took me a second to understand what Lacey was asking for, but it suddenly clicked. I had absolutely no problem with the idea and got up. I laid down next to Lacey on the bed. Positioning my self on the bed so that my crotch was next to her face, and vice-verse was quite a task. We managed to figure it out though.

A pushed up Lacey's skirt up as I heard my pants unzip. I couldn't believe what I was looking at. Lacey had forgone panties, so staring me in the face was a perfect, hairless, 13 year old vagina. A moment later, I felt a tiny hand wrap around my shaft as it was pulled out of my boxers. At the same time, me and Lacey buried ourselves into each other's crotches.

I started licking at and around Lacey's clit. The sweet taste of her pussy made me thrust my hips in appreciation. Lacey, despite this being only the second time she gave a blowjob, was already getting good at it. She occasionally took my dick out of her mouth and ran her tongue up and down my rod. I was in absolute heaven at the moment. When I started to flick Lacey's clit, I heard and felt a moan on my penis. By this point, Lacey had managed to fit most of my cock in her mouth. My dick was near her throat when she moaned. Causing the vibrations to hit the cock. I gave an involuntary moan of my own at the feeling.

Redoubling my efforts I started lapping Lacey's pussy like a thirsty dog at a river. Feeling the climax coming I began to thrust into my sister. I heard a loud moan as she stopped moving. Forcing myself to thrust faster, I suddenly stopped and began to spasm. I unleashed all the cum I had building up over the past few days. Lacey, to give her credit, tried to swallow it. I was impressed actually. Unfortunately, she wasn't used to the taste and was recovering from her orgasm. This was compounded by the sheer quantity of it, and her having never swallowed.

My cum began to dribble out of Lacey's mouth, pooling on the bed. I pulled my dick out of Lacey's lips and pulled my own face away from her. Looking up at her, I couldn't but smile. I now knew Lacey at least wanted this. She enjoyed being with me, and had no problem performing the sexual acts. We got up and I tossed my sheets into the wash. Putting some fresh ones in place, I pulled Lacey to me. That night, I fell asleep with my 13 year old sister in my arms.