Bianca and Carla were both sisters and best friends and had always gone on nights out together. The more academic of the pair, Carla was at college while Bianca worked in a local bar. They both believed in working hard - but playing even harder, which they did as often as possible.

They had contrasting appearances, Bianca being dark and Carla fair. Still, each had a gorgeous, thick mane of hair flowing down to neat waists, framing their petite, pert bodies.

Early one Saturday evening, they were getting ready to go out and had already polished off a bottle of wine. They were now downing vodka and fresh orange juice, music blasting around the room to get them in a party mood.

Bianca held up two bra and knicker sets, black in one hand and red in the other. 'Which one?'

Carla cocked her head to one side. 'I like the black one. I always think black is sexy.'

Bianca shrugged her bathrobe from her shoulders, letting it fall to the floor and displaying her naked body. Carla looked away quickly, slightly embarrassed. 'God, I wish you wouldn't do that; it's weird seeing you standing there totally naked.'

'Oh, don't be such a prude,' Bianca protested. 'I don't have anything different than you. Well, apart from bigger tits.'

Carla self-consciously pulled her bathrobe belt tighter around her waist before picking up curling tongs to begin the laborious task of curling her thick, luscious hair.

Bianca looked in her compact mirror, pouting her plump lips. She had always been the more dominant of the sisters; hence, her hair had been curled an hour earlier - she'd insisted on the first use of their shared tongs.

Not only was Bianca the most domineering of the two, but she was also the most sexually promiscuous. She'd lost her virginity three years ago and hadn't wasted any time since then in her pursuit of cock. Carla's purity had always given Bianca a sense of wonder and curiosity.

Throughout their childhood, Bianca had always won when they played board games. If she didn't win, she would throw a tantrum, and, for Carla, it wasn't worth the hassle for any small victory of her own. Their father always took Bianca's side and said he liked her free spirit. He also didn't seem to mind when Bianca walked around the house naked in her teenage years. Their father welcomed Bianca's professed 'being at one with nature phase'.

'Not everyone wants to be a little slut, you know,' their mother would say, her mouth contorted in distaste. 'At least one of our daughters has the decency to behave herself.'

Carla had kept her teenage sexual stirrings under wraps, masturbating quietly in the privacy of her bedroom. Bianca, however, was noisy when she masturbated, and, at times, she didn't even bother to lock her bedroom door. She'd laughed when she told Carla about their father accidentally walking in on her.

Apparently, he had been mortified and hastily retreated. It was a story that Carla had wished that Bianca had kept to herself because, at the time, Carla had blushed so violently at her sister's revelation that she had felt like her cheeks would melt under the heat of her embarrassment.

There were no secrets with Bianca, and unfortunately for the innocent Carla, she was subjected to more of Bianca's stories. It was like Carla was her confidante, and Bianca wasn't aware that her sister was an unwilling one. Even if she did know, it wouldn't have stopped her.

Bianca had also confided once to Carla that Uncle Mike, a family friend, had kissed her on the landing on the night of a Christmas family get-together. Carla had caught him a few times looking at her, his eyes lasciviously roving over her body. Although it made her uncomfortable, she was secretly thrilled that he possibly found her attractive.

Apparently, the night he kissed Bianca, he'd put his hands up her skirt and pulled her knickers to one side. Bianca giggled, her eyes alight as she described how his fingers had probed her opening before delving inside her.

'I was a virgin at the time,' Bianca recalled. 'After that, getting fucked was all I could think about.'

Although her sister's secrets often appalled Carla, she secretly got off on her sister's provocative behaviour, even if she didn't want to admit it.

'When are you going to finally have sex?' Bianca asked before snapping shut her compact mirror, giving Carla a look so intense it caused her sister's chest to flush.

'I just haven't met anyone I want to have sex with, if that's okay with you,' Carla retorted.

Bianca snorted, 'Of course you have. Many guys have been interested in you, and you have fancied a couple of them yourself. Are you scared about the whole thing or what?' Bianca raised her eyebrows. 'If that's the case, let me tell you there is nothing to be frightened of. Okay, it hurts the first time, but that doesn't last long; you soon get into it.'

Bianca fastened her bra, arranging her breasts into the cups to ensure her cleavage was full and inviting. 'Honestly,' she continued, 'the pain only lasts for the first few minutes as they push inside you. It's obviously going to hurt a bit. After all, it's like shoving a huge sausage into a keyhole.'

Bianca turned this way and that, appraising her reflection in the bedroom mirror. 'The human body is amazing,' she added, jiggling her breasts. 'Once your pussy adjusts, trust me, it's fucking awesome.'

Carla felt her cheeks warm, the familiar sign that she was blushing. Unwittingly, Bianca had hit the proverbial nail on the head: Carla was scared about having sex. She'd been worried for so long that she consoled herself with the fact that, if there was some mystical sexual quota, Bianca was definitely having enough for both of them.

Lately, though, Carla had found herself coveting Bianca's new boyfriend, Dillon. In Carla's eyes, Dillon was gorgeous with his deep-set green eyes, olive skin, and fantastic physique. Not that Carla had ever seen his physique in the flesh. She'd only seen it within his tight ribbed t-shirts, but his muscular pecs and his boyish charm stirred up feelings in Carla that she had never experienced.

Of course, their mother clearly disapproved of Dillon. Boyish charm, cockiness and a self-assured demeanour were never going to endear him to their mother. However, she hadn't protested because she knew that her opposition would encourage Bianca even more. So, whenever Dillon came round, their mother was dutifully pleasant to his face when both girls knew damn well she was seething inside. Like now as she announced Dillon's arrival.

'Bianca, Dillon is here.' Their mother shouted shrilly from the hallway.

Quickly - and not before time, Carla thought - Bianca finally pulled her knickers on, concealing her shaven pussy within the minuscule black lacy triangle. Bianca grinned at her and flicked her hair over her shoulders.

'I won't be a minute,' she said, leaving the bedroom wearing only her knickers and bra. 'Send Dillon up, Mum,' she shouted from the stairs.

Carla's stomach somersaulted with nerves. If she'd known Dillon would turn up, she would have got ready in the privacy and safety of her own bedroom.

Reaching across the dressing table, Carla lifted her glass of vodka and downed it to steady her nerves. She slammed the glass down just as the bedroom door opened. Standing in the doorway, Bianca motioned for Dillon to step inside.

Carla noticed that he entered the room with relish. He smiled in Carla's direction, and she nervously smiled back before turning her attention back to curling her hair.

'I told you I was going out,' Bianca admonished Dillon, shutting the bedroom door and sliding the lock across.

'I thought I would call and see you,' Dillon drawled. 'Is that okay?'

Carla kept looking straight ahead as she finished curling her hair. Putting the curlers on the dressing table, she bent and unplugged them. She started to busily look through her makeup bag, trying to decide what shade of eye shadow to wear. That was preferable to thinking about the awkward fact that she was locked in a bedroom with her sister and boyfriend.

'Well, now you've seen me, what do you think?' Bianca asked, turning down the music.

'I think,' said Dillon, his voice thick with evident desire, 'in that get-up, you need a hard fucking, to be honest.'

Bianca giggled. 'Oooh, what an excellent idea. We are not going out for another hour.'

Carla felt herself shrivel up inside as she watched Bianca push Dillon onto the bed beside her before straddling his thick, denim-clad thighs.

Carla averted her eyes again and took a palette of eye shadow from her makeup bag. The sound of Bianca's and Dillon's wet kisses permeated the tense atmosphere of the room. Nervously, Carla reached for the bottle of vodka and poured a hefty measure, topping up the rest of the glass with orange juice.

Admittedly, she already felt squiffy, but in this situation, she needed to deaden her anxiety. Carla also realised that if she wanted to bolt the proverbial stable, she would have to leap the hurdle of Dillon and Bianca.

Bianca was grinding her pussy against Dillon's crotch, causing him to groan with deep, masculine, unadulterated pleasure. Carla decided that her best option was to speak up before things escalated.

Abandoning applying eyeshadow, she popped it back in her makeup bag. She took another swig of her drink before clearing her throat, trying to get Bianca's attention. 'Erm, I think I'll leave you two alone and get ready in my room.'

Standing up, Carla felt a slight wobble in her legs, confirming that she had definitely drunk more than she should have. It took a few seconds to focus her eyes. With an extreme effort, she manoeuvred through the tight space between the dressing table and the edge of the bed.

Carla felt Bianca's hand push her on the shoulder in one sharp, swift move. The movement, without the stimulus of alcohol, would not have had any effect on Carla whatsoever. However, it now had the impact of a boxer being knocked over. Carla fell backwards onto the bed.

'You don't have to leave,' Bianca insisted. 'We want Carla to stay, don't we, Dillon?'

Bianca's words seemed to pull Dillon out of his horny coma. He looked at Carla as if he'd only become aware of her presence in that second. He looked back at Bianca, his eyes glazed over like he was under her spell. Carla hoped he would do the gentlemanly thing, insist that he and Bianca had time alone. Indeed, he must have thought this scenario was weird. Instead, Carla watched his broad shoulders shrug.

'She can stay with us if she wants,' he grinned. 'The more, the merrier in my eyes.'

Carla saw a self-satisfied smirk cross Bianca's lips. 'I knew you would be up for it, baby,' she said, slowly unzipping his jeans. 'Now, you sit there and learn a thing or two, Carla.

Ten minutes later, Carla was transfixed as she watched Bianca's lips move up and down Dillon's cock. It was the first time Carla had seen a cock in the flesh. She couldn't understand how her sister could take something so rigid and long in her mouth. And with such vigour.

Carla also struggled to fathom how her sister's mouth could create such a film of slime and foam, which was now coating Dillon's balls. Carla watched Bianca suck and simultaneously rub the bubbles, massaging Dillon with expertise.

Despite herself, and even though she knew deep down it was wrong, Carla felt a stirring inside. Her pussy, which had never been invaded by anything but her finger, but Bianca and Dillon's antics were emitting feelings she'd never experienced.

She watched as her sister stopped her pornstar-quality sucking and moved her black lace knickers to one side before climbing on top of Dillon, taking his thick cock inside. Carla tilted her head to one side, inching closer to get a better view whilst rubbing her pussy beneath the confines of her bathrobe.

Dillon's cock was now absolutely saturated with Bianca's juices, and suddenly, they all increased their pace, Carla rubbing her pussy in synchronisation with the rhythm of the couple fucking wildly at her side.

Bianca let out a loud moan, announcing the arrival of her orgasm before she clambered off Dillon and took his cock into her mouth. She ran her tongue up and down his length, lasciviously licking off her juices. Then she looked at the cock throbbing in her hand… and held it out towards Carla.

'Want some?'