This year was the first time I had been home in a long time. Our family was never super close. Usual story – Dad was always away on business, Mom spent long hours with her research projects at the university. That left me watching my little sister Julie and having no social life. When I had the opportunity to go to college at an Ivy back East, I took it without a second thought.

I always expected to go home, but one thing after another came up and suddenly three years had gone by. This holiday break, I wasn't dating anyone and didn't have to work, so when Mom offered to fly me back I had no choice to take her up on it.

Mom and Dad haven't changed much, but my little sister sure had. When I left she was a dorky kid with braces who could just talk about the next boy band. Now she had grown up in more ways than one. While talking with her about college and her plans for next year my eyes kept falling to her perky breast, which strained against the gauzy fabric of her halter-top. And every time she licked her pouty lips I could feel my cock twinge and thought of all the hearts she must be breaking.

That first night, as I lay in my old bedroom, I couldn't stop thinking about how hot Julie was now. Sure it was weird thinking about my sister that way, but I couldn't help it. Restless and horny I wandered downstairs in just my boxers to get a midnight snack.

"Hi bro." Julie said as I entered the family room. My little sister was a wet dream watching cartoons on cable TV. She was sitting on the couch with her tan legs stretched across to the coffee table wearing just a pair of white panties peeking out from beneath her pink nightshirt.

"What's up Squirt?" I asked trying to remember her as the girl I took to pee-wee soccer and checked her math homework.

"You dick. No one calls me 'Squirt' any more." She said with a mock frown. "Come sit down and hang out with me for awhile."

"I would, but I'm not really dressed for it." I said trying not to point out that my boxers were a size smaller on me after seeing her sitting half naked.

"Oh don't be a prude, neither am I. Come on, I want my big brother to sit with me."

I sat next to her, and tried to act like this was normal. I'm pretty comfortable with my body. At 20 years old I was probably in as good of shape as I would ever be. But I'm not usually sitting nearly nude next to a sexy teen in an equal state of undress.

For awhile I lost myself in Adult Swim, but Julie had an infectious giggle and I kept glancing over at her. In the end I couldn't keep my eyes on the TV because they kept wandering to her creamy thighs. When she noticed she smiled, but pulled her legs up onto the couch and hugged them to her.

At first I was mentally kicking myself, thinking I had made her uncomfortable. Then I noticed out of the corner of my eye that she was coyly letting her legs part. They slowly split drifting apart and her white undies shone in the shadows between them. When I saw the damp spot on the crotch of her panties framed between her thighs I unconsciously did a double take and my cock immediately started to stiffen. Julie realized where I was looking and with her cute giggle said, "Oh Rodger, you are such a perv. But then I guess so am I for teasing you."

Still smiling Julie moved around to lean against me. I figured this was a sign and I knew I had to take action. My hand gently slid over the jersey knit cloth of her shirt and circled around her full breast flicking the ridged nipple I felt there. When Julie gasped and stiffened against me I assumed I had made the mistake of my lifetime. Hoping I couldn't make things any worse I went for broke by kissing her as she asked, "Roger, what are you..."

When I leaned back I expected Julie to scream, to hit me, to get up and storm out to wake our parents. But instead she moved forward for another kiss. I pulled her onto my lap as we spent long, incredible minutes making out in a very un-sibling like way.

Julie moved around on my lap and straddled me so that both of her breasts were rubbing against my chest. I could feel my cock pressing up between her tight little thighs as I moved my hands down to her waist. Through the thin fabric of her panties and my boxers I could feel the wet warmth of her cunny pressed against me. The lips of her pussy parted a little when I ground my head up to her and she hissed against my mouth.

I pushed my little sister backward on the couch and tugged her nightshirt up exposing her round ripe breasts, which were pushed up by a white cotton bra dotted with little cherries. I put my hands around her back and managed to undo the clasp with a quick flick of my fingers. At least I had learned something at college. Once her breasts were free I admired her hard nipples and couldn't resist moving down to pay them homage. I suckled at both of Julie's breast, and then continued downward, pulling off her panties.