Tom couldn't quite believe it. Surely not. He tried again.

"I'm sorry, I didn't catch that. I thought you said you were Lisa's friend Liberty."

She smiled a devastating half grin at him. "Silly! Tom, it's me, Libby! I've not changed that much!"

She had. The leggy brunette wearing jeans and a heart-stoppingly tight t-shirt standing on the doorstep was not the geeky awkward girl who used to hang around with his little sister, but there was no mistaking that English accent.

"Wow. I mean... hang on." Tom stepped back, closed the door on her and bellowed "LISAAA!!".

"Is she here? She's here isn't she! Cooool!" Lisa squealed as she shot down the stairs. "You didn't leave her out there? You're such a dork," she said as she ran past him and threw open the door. Both girls screamed in unison. Tom stood there and gaped as he watched these two nubile sixteen year olds locked in hug after full-bodied hug. He was expecting a friend of Lisa's to turn up for the end of the summer, not this gorgeous young woman. His hand automatically dropped to his crotch, but then he realised the blonde bombshell with her was his sister. When did that happen? he wondered. Tom shuddered and left them to it.

That night, Tom turned over again in his childhood bed, trying to get comfortable and ignore the squeals and giggles coming from his sister's room. A glance at the clock told him it was past 1am. Enough was enough. He kicked back the covers and walked as far as the door in nothing but his boxers when he heard the sound of Liberty's voice. His cock twitched. "Lisa's geeky friend... Lisa's geeky friend" was his mantra as he grabbed his jeans, pulled them on and strode down the hall.

He didn't bother knocking and both girls jumped as he opened the door. They were sat cross-legged on Lisa's bed, both wearing what he recognised as his old t-shirts. Two pairs of impossibly long, slender, lightly toned and tanned legs swung to the floor. Tom almost forgot why he was standing there as he got an eyeful of white cotton panties.

Lisa reminded him. "Last I checked this was MY room, you pervy dickhead. Get out!"

"If you kept the noise down I wouldn't be in here. You've got weeks to catch up — do you have to do it right now?" Tom flicked off the bright overhead light and turned on Lisa's bedside lamp. A low soft glow lit the room. "That's better. If it's not so bright you might not be so loud. Look Lise, you know you've got it so easy with me baby-sitting — " The look of offence on her face was priceless, but rather than engage in full warfare with his sister Tom opted for retreat, " — I mean house-sitting while Mom and Dad are away."

"Yeah right. You only offered because your apartment stinks," she retorted. Tom wondered how on earth he could have thought this little toe-rag had actually grown up.

"Hey, do I say that about your room? I've got to go to work tomorrow and you two need your beauty sleep. Now get to bed!"

Lisa scowled at him, but didn't reply as the two girls scrambled under the covers of her double bed. Tom crossed his arms over his bare chest and looked at them. "Isn't Liberty in the spare room while she's staying here?"

Liberty sat up fast. "Oh, please, can't I stay in Lisa's room for a couple of nights? It's so nice to be back and we're having such a lovely time, Tom. Please?" He looked at her and had to look away again. This girl was growing into a serious heart-breaker.

"Fine with me. Just no noise. Deal?" Both girls shuffled in the bed and nodded their heads.

Back in his own room, Tom shut the door, leaned against it and let out a long breath. Somehow this sister-sitting was turning out to be harder than he thought. Much harder.

"Oh — my — God. When did Tom get so cute?" Liberty whispered to Lisa. The girls had rolled to face each other and quietly carried on their conversation when Tom left the room. "I don't remember him having muscles like that!"

"Euuugh, Libby, no way! That's my brother!" Lisa hissed back. "Since he moved out he thinks he's such the big man. He's more unbearable than ever!"

Liberty and Lisa had been friends since they met on a school exchange program when they were ten. Since then, they'd spent weeks every summer alternating visits, and for the last two summers, Lisa had gone to Liberty's family in London. She knew Lisa well enough to know she was exaggerating - she adored her older brother.

"He is handsome though." Liberty sighed. "So gorgeous."

"Are you serious? He's twenty-five next birthday. That's so old. Way too old for you. Anyway - what about all your hot English boyfriends? I wish you'd brought one with you for me!"

Liberty rolled her eyes. "Bumbling, fumbling morons. That's what they are. You know I told you I was seeing William for a couple of months? As soon as he heard I was coming out here, he started asking me to, you know, do it, as a going away present for him. When I told him I didn't think I was ready, he dumped me! No bad thing really. He'd shown me his cock and it was really skinny."

They collapsed in fits of giggles.

For the first week, Tom had made a point of looking after the girls really well, and he and Lisa were getting on better than ever. Their age gap had always been a bit of a issue for him — he never wanted his baby sister and her friends hanging around with him as he was growing up — but as they got older they had more in common, and he enjoyed her company. And Liberty's company. Especially Liberty's company.

He'd managed to convince himself that she was still Lisa's geeky friend, until last night. He'd invited a couple of friends over to watch a movie and have a beer. They drank the beer and watched Liberty watch the movie. As they left, he overheard them discussing how hot Lisa and her friend had got, and was seriously pissed off. Because it was his sister. And her friend. And it was true.

It was Saturday morning. Lisa was at her weekend job at her favourite clothes store in the mall. She spent so much money in there, their Mom had decided that it was about time Lisa started earning some of it back. Tom was starting the weekend the way he intended for it to continue, laid out full length on the sofa in front of dire Saturday morning TV, fingering a condom in his pocket (left over from the last time he wore these shorts to a particularly memorable pool party) and contemplating his first wank of the day.

Suddenly, he heard Liberty's voice coming from the study, getting louder and louder. He heard her slam down the phone and she stormed in. Tom was instantly very aware that he wearing just a pair of shorts and got up to go and put on more clothes. "Er, hi Liberty. I thought you'd gone with Lisa this morning... are you OK?" She looked like she wanted to cry. Tom suddenly felt very protective of her. "Come on. What about a cup a tea?" She gave a small smile at his awful attempt at an English accent, but it just made her look sadder. Tom led the way into the kitchen. She perched on a stool at the breakfast bar as Tom boiled the kettle and rummaged in the cupboard "I know Mom's got tea bags in here somewhere — they might be a bit old though."

"I didn't mean to make a fuss." Liberty said quietly.

Tom's heart ached for her, but he made himself carry on with the tea. "Do you want to talk about it? I might be Lisa's horrible brother, but maybe I can help."

Liberty smiled properly. "You're not horrible. You're the loveliest man I know. It's nothing, really. I just..." Her perfectly rounded chest hitched and Tom passed her a tissue. "My boyfriend's dumped me."

Tom put a steaming cup of tea with sugar in front of her, and leaned on the other side of the bar with his coffee. "Lisa mentioned this the other day. I thought that happened before you left."

"Yes, well, we kind of made up."

"Isn't that a good thing?"

"No." She took a deep breath and squinted her eyes shut. Her words came out in a rush. "He only made up with me because I said I'd do it with him when I got back but I just found out that he's been going out with Chloe Morgan." The contempt with which she said the other girl's name told Tom a lot.

"Not a nice girl, then."

"You could say that. She's ghastly. All the boys like her but only because she lets them touch her and... you know... her."

"Fuck." The word slipped out before Tom could stop it.

Liberty blushed but didn't stop. "She lets them touch her and fuck her. She's been doing it since she was fourteen." Her chest hitched again. "I really thought William liked me. He's such a fucker." The tears started to flow. Tom came round the table, stood her up, took her in his arms and held her tight to his chest. Her arms wound around him and held him just as tightly. He lowered his head and murmured soothing sounds into her hair. Eventually she calmed down, but didn't let him go. Tom gradually became more and more aware of her hot body pressed to his, the feel of her soft breasts through her t-shirt against his bare chest. His cock had started to harden when Liberty pushed herself against it. Tom didn't dare let go of her now — he had no way of hiding the erection she'd given him, and he had a feeling she'd already noticed it.