Expensive Upgrade

Carefully, Libby afforded herself a look back over her shoulder and called out in response. "Yeah, you better bring it out here as quickly as you can. I'm absolutely starving, all I've had in the last few hours is this wine." Slowly, Libby looked back into Fiona's eyes as she reached up towards her own chest and pulled the thin black cups of her bikini top back into place.

With her cleavage restored and the healthy portion of her breasts showing from under the small garment, Libby giggled softly and spoke up. "It must be almost 18 months ago by now... I was staying here at the house during my Christmas holiday. Callum was seeing this girl, honestly, Fiona...she was absolutely stunning. She was like a little blonde airhead, but I couldn't stop staring at her tits every time she came round to see him..." Libby allowed the comment to hang in the air as she remained straddling Fiona's lap with intent. "One of the first nights she stayed over, it was pitch black in the hallway and it must've been about 2:00 a.m. I was lying in bed watching a movie on my laptop when my bedroom door opened and she stumbled inside... Of course, when she realised her mistake, she apologised and went to go back into Callum's room..."

As Fiona listened to the story, the memories of what she just experienced started searing themselves into her mind. The heat of the kiss and the way Libby's body felt as her hands roamed all over it, all while she hopelessly surrendered as her pussy got so wet. It felt like she'd just went through an event so transformative that she was a whole new person as she remained there, trapped under Libby's weight. But the aura that the redhead wielded ensured that she paid the utmost attention as Libby's story continued, with Fiona's eyes ensnared by Libby's gaze.

The short silence felt like an eternity before Libby giggled and continued. "Now, what kind of host would I have been if I'd have just let that little bimbo tiptoe back into my brother's room? Let me assure you, Fiona...that was never going to happen. Once I pulled her back inside and sat her on the bed, she told me that Callum had fallen asleep. Well, I wasn't going to let that opportunity slip away, was I? From there, it really didn't take long for me to rip two pillowcases free and wrap them around her wrists, tying her to my bed...and I spent the next hour riding her pretty face until she started begging me to lick her wet little pussy..."

Despite her best efforts to maintain her composure, the memory elicited a long groan from Libby as her eyes briefly fluttered. After a moment, Libby calmed herself and returned to Fiona's gaze. "I can't wait for you to get lost and stumble into my room... I've still got the same two pillowcases that I used on that gorgeous little blonde. Mind you, the way you just kissed me...the way your hands felt against these tits...I don't think you'll need to be lost to find your way into my bedroom... Just know that once I get you inside, don't think I'm going to let you out until you feel my tongue dancing across that little pussy of yours...and I'm going to take my time..."

Just as Libby started to finally retreat from her position, crawling out of Fiona's lap and reaching across her shoulder to retrieve her phone, Callum walked towards the sliding doors and stepped out onto the decking. In his right hand was a large plate with lightly-salted chicken breasts that had been clumsily wrapped up just moments earlier. Fiona glanced across at him as she felt the relief of Libby's weight leaving her lap, but the guilt of what had just transpired was written all over her face through the intense redness of her cheeks.

As Callum approached the edge of the hot tub, Fiona calculated that he was too close for her to offer a genuine response to Libby's scorching tease. She knew, of course, that Libby was being straight with her. She had no doubt in her mind that she thought nothing of fucking Callum's ex-girlfriend while he slept, oblivious, in the next room. Meanwhile, there was no doubt in Fiona's mind, whatsoever, that Libby wanted her in the exact same way. Bound, struggling, panting with need...as Libby's glistening pussy dropped itself squarely onto her face. Even as the thought had barely formed in her mind, Fiona cursed herself as she felt the heat between her own legs which simply didn't care if she ended up cheating on Callum as Libby's helpless plaything.

As soon as the realisation settled within her own mind, Fiona stood up in the hot tub and started walking towards the steps. Without hesitation, Fiona climbed out of the water and stood up on the decking as she looked into Callum's eyes. With the knowledge of her own infidelity eating away at her, Callum's girlfriend knew that she wanted to be anywhere but around Libby at that time. With a slight grimace, Fiona spoke up. "Babe, I know I drove over here tonight, but there must've been something in that wine that isn't agreeing with me. I'm going to call a taxi and spend the night at home in bed, I'll call you in the morning and we can make plans for the day?"

Slowly, Callum sat the plate of chicken down near the edge of the hot tub as he stood up straight and looked into Fiona's eyes. "Are you sure? Whatever it is that you're feeling, it must've hit you pretty fast... I can come with you, we can just chill and get an early night if you aren't feeling too good..."

At that moment, Fiona's legs started moving almost on their own as she raced towards the back door. "No, no...stay here with Libby, she's just arrived... You two have got a lot to catch up on, I'll be fine. Just stay out here, I'm literally going to order a taxi right now and just grab my stuff and go. Once I've had some rest and I'm feeling better, the three of us can spend some more time together..."

However, as Fiona practically bolted inside, Libby's gorgeous face wore the most sinister smile as Callum's back was facing her. Libby appreciated the sight of Fiona's tight cheeks as she went into her obvious retreat, but she savoured the victory of having driven her brother's girlfriend away for the rest of the evening. As Fiona disappeared from view and Callum started to turn back around to face her, Libby was overjoyed by the prospect of Fiona feeling too awkward to return on account of her being there. It was then that Libby teased herself with the fact that she'd be spending the next 13 days at home with her gorgeous brother, all alone with no one to get between them.

A few hours later, it was just after midnight when Callum walked into his bedroom and made sure to close the door tightly shut behind him. After Fiona's abrupt departure, Callum had spent the rest of the evening in the hot tub with Libby as he struggled to find the strength to stop ogling her sensational curves without getting caught. But as he pulled his wet shorts off and tossed them into his laundry basket, all it took was the faintest recollection of the way Libby's tits sat so proudly on her chest and Callum could do nothing to stop himself from swelling to full hardness.

With just the lamp switched on atop his bedside cabinet, Callum didn't even dry the remaining moisture from his legs and feet before he sat down on the edge of his bed. After taking a moment to try and gather his thoughts, Callum swore that he was starting to lose his mind by the way that his sister's stunning body was captivating his thoughts. At that point, he reached out and grabbed his phone as he desperately tried to disassociate his current state of arousal from Libby's mesmerising assets.

Frantically, Callum climbed up onto his bed and lay on top of his duvet, completely naked, as his rock-hard dick was throbbing and desperate for release. Initially, Callum opened his Instagram feed where he followed a who's who of the world's hottest models, where he was certain that he could convince himself that his straining erection could be attributed towards someone else...anyone else... But as he scrolled down through his feed, with stunning fitness models and influencers poured into the most scandalous lingerie and swimsuits, it felt to Callum like nothing was grabbing his attention, not even his absolute favourites.

Due to the lateness of the hour, Callum dropped his phone down onto the bed for a moment as his eyes briefly closed. But once they did, they failed to open back up as something in the darkest parts of his mind took a firm hold of him as he saw himself standing inside a strange room.

Quizzically, Callum tried to understand what his mind was showing him, but he didn't recognise much of his surroundings. He was sitting on the black leather couch from his living room in just a tight pair of black boxers, but he was enclosed within a glass box that was no larger than his bedroom. Meanwhile, the thick glass walls and ceiling were positioned in the middle of what appeared to be some kind of control room, with various engineers in lab coats manning their stations all around the perimeter of the area. As Callum looked around, it seemed like he was in a fairly calm environment, but he noticed that some of the instruments and workstations had small plumes of smoke and flashing amber lights that were commanding the engineers' attention.

As the scene that his mind was painting for him continued to play out, Callum went to stand to his feet before he realised that he wasn't alone. When he looked up, the figure of Libby suddenly appeared right in front of him as her body was still gleaming from their evening in the hot tub. Her smouldering enhanced tits were threatening to break loose from the tight black fabric of her bikini top, while the way her bottoms clung so tightly to the smooth skin above her hips had Callum almost panting with desire. While Libby's awesome figure crept closer, Callum froze in position on the couch as her sudden appearance in the strange room resulted in more amber lights flashing all around the perimeter surrounding them.

Once Libby was standing directly in front of her brother in the glass box, with him sat on the couch, she took a moment to look all around the room at the different engineers, lights and consoles. It was then that she returned to her brother's gaze and spoke first. "They seem to be in some kind of distress... I wonder what it could be that's gotten them so worked up? Perhaps it's because you saw something out in the hot tub that's left you a little hot under the collar?" Slowly, Libby's right hand crawled up her body until she allowed herself a long, firm grope of her own breast as she moaned right in front of Callum's face. "If you're telling yourself that I wouldn't have noticed all those glances at these big tits...just how hard that big dick got for me under the water... If you're going to insist on telling yourself those lies, then you're going to need a new strategy to deal with the chaos that's about to unfold right here in this room..."

While the fantasy was deeply unsettling to him, Callum knew that he could engage with the image of his sister as he was really alone in his bedroom. But the entire scene felt so real to him, like his subconscious had been stirred in such a way that the lurid picture which it was painting was almost inescapable. As his lips parted, he looked into Libby's dark brown eyes and responded. "I don't know why we're here together...why we're here in the middle of this room...but there isn't going to be any chaos. I don't know what it was, I just haven't seen you in so long... Fiona and I had been drinking, whatever reaction I had to you was just a complete one-off..."

The smile on Libby's face conveyed just how little she cared for his objections as she began to twirl around slowly. While she did, Callum's sister ensured that he got a perfect view of her toned thighs and tight cheeks, with her bronzed skin looking absolutely glorious with just the tiny scrap of black fabric covering her perfect breasts. When she stood back in front of him and looked him in the eye once more, Libby giggled as she responded. "Now that you're all on your own and your girlfriend's not there to stop you, why don't you do what you've been dying to from the moment you saw me in this tight fucking bikini? It's time for you to take a nice deep breath and imagine what it would be like for me to crawl into your lap, with these big tits so close to your face...before I lean in and slip my tongue into your mouth..."

When the sinful words spilled out into the air, more plumes of smoke started to spray out from different pieces of equipment around the perimeter of the room. After a couple of amber lights turned red and more of the engineers started to run across to address the problems, Callum felt Libby creeping closer as she glanced down and saw just how hard his bulge was beneath his boxers. When her movement didn't stop, Callum gritted his teeth as he visualised Libby crawling into his lap until he felt her hips dropping.

Immediately, Callum's eyes opened as he lay atop his bed and he leapt up onto his feet. A few beads of sweat had formed on his brow as he tried to comprehend just what his mind had shown him. So much of him knew that Libby looked amazing out in the hot tub, but he was dismayed to find that her imprint had been left on him to the degree where he just fantasised about her while his dick was as hard as it had been in a long time. But it wasn't just her physical appearance that had enthralled him, as the way her wicked aura descended upon him whenever she talked about her busy sex life was threatening to rewire his brain. As he stood there, alone in his bedroom, Callum realised that whatever spell his sister was capable of casting on him, it was going to be a long two weeks alone with her if he couldn't pull himself together.

With haste, Callum pulled on his boxers, t-shirt and tracksuit bottoms that he'd changed out of to go into the pool and stepped into a pair of running shoes. He almost had to force himself to think about his girlfriend as he left his bedroom with the intention of going for a late-night run to clear his head. But as he walked out of the front door of the house and closed it behind him, any thoughts he had of Fiona's wellbeing were firmly replaced by the thought of Libby peeling her scandalous bikini top off while she was alone in her bedroom.

Two days later, Callum was sitting on the black leather couch in the living room as he was spending the early part of his Saturday afternoon watching motor racing highlights on television. The great weather in Glasgow had continued as the resultant heat had led to Callum sitting in just a pair of black running shorts and a simple matching t-shirt.

It was just after 1:00 p.m. when Callum tried to gather his thoughts as he watched the expensive cars race around the track in a qualifying session. Since Fiona's abrupt departure two nights earlier, she'd been in touch to let him know that whatever bug she'd come down with had left her bedridden. While his girlfriend's story was technically true in that she'd spent so much time in bed, he wasn't to know that the bug she'd come down with was his gorgeous sister. In truth, Fiona had spent so much time in bed setting aside her guilt and playing with her pussy, she'd barely managed to squeeze in the time to call Callum and assure him she was doing fine on her own.

As he lay back against the comfortable leather couch, Callum was immediately distracted by the sound of the living room door slowly opening. When he turned to anticipate his sister's imminent arrival, all it took was one look at her and his guilt came flooding back from when he fantasised about her after their night in the pool.

Callum simply couldn't peel his eyes away from her as Libby almost bounced into the living room, with a big smile plastered all over her pretty face. Her long red hair was tied up into a messy bun, with strands of hair flowing down from her fringe either side of her face to meet her chin. But every little step she took resulted in her breasts jiggling and softly bouncing as her thin pink cardigan was offering her enhanced chest very little support. The cardigan was long-sleeved, but the hem was slightly cropped to ride above the waistband of her matching pink pyjama shorts. Meanwhile, the only three buttons on the cardigan were clustered directly under her breasts, which allowed the neckline to swoop so low that the cleavage Libby was displaying left Callum needing to take a deep breath.

When she reached the couch, Libby playfully jumped down onto the seat to his left and spoke up. "I only got up an hour or so ago, I was up half the night texting someone new that I've met... Honestly, Callum, I'm going to need you to come into my room and take this phone out of my hand if I do that again. It was daylight outside when I finally went to sleep...." Once she was content that his eyes hadn't managed to free themselves from her body, Libby giggled as she held her phone in her right hand. But as her bare legs pressed themselves against his, Libby leaned in closer towards him and continued. "Have you got any plans with Fiona today? Is she feeling any better now that she's got some sleep?"

In his current state of mind, the last thing Callum wanted was to feel his sister's smooth skin brushing up against his bare legs. However, the thought was only allowed to form in his mind for a moment before he realised that he needed to focus all of his attention on not glancing down at her cleavage as it sat right in front of his face. After sucking down a further deep breath, Callum compelled himself to hold his sister's gaze as he responded. "I still don't know what's going on with Fiona, she called me this morning and said that she's feeling a bit better...but that she's going to spend the weekend in bed. I told her that she could stay in my room for the next few days, but she said she doesn't want either of us to catch whatever she's got... We never spoke on the phone for very long, but...I don't know... It just seems like she's got a lot on her mind and it's happened out of the blue..."

For a moment, Libby allowed herself to flash her brother a sympathetic look before her natural instinct took over. As the grin crept back onto her face, Libby purred. "That's such a shame, I was hoping that the three of us could spend so much time together before Mum and Dad get back... Isn't she gorgeous though? Fiona's got such a tight little body... It's probably for the best that she can't come over, or else you two would be spending all day in bed and I'd be left feeling like a spare part..." As the grin widened across her pretty face, Libby continued. "Not to worry though, that just leaves you and me on our own. We've spent so little time together this last year...we're going to have to get to know each other all over again... If you think about it Callum, it's almost as if we've become strangers instead of siblings..."

Briefly, Callum contemplated Fiona's thoughts from before Libby arrived. While he knew that both his girlfriend and sister were right, that he hadn't made the right effort to maintain his relationship with Libby, the events since Libby's arrival had just reinforced his level of discomfort. Even as he sat there next to her on the couch, Callum was almost dumbstruck by how difficult his sister's new assets were to conceal. The way the thin pink material clung so tightly around her upper body had him wondering if she truly cared whether her cleavage was inappropriate considering it was just the two of them at home together. As she gently twisted and turned, Callum could clearly see a healthy glimpse of the black lace of her bra as it crept into view, which offered Libby's breasts an extra degree of lift that she hardly needed.

Once he realised that his gaze had somehow slipped back down to appraise her cleavage, Callum silently rebuked himself as his head snapped back upwards until he was looking into her deep hazel eyes. "You don't need to worry about that, I'm still the same guy I've always been... But you're right, there's going to be plenty of things we can do together over the next week or so. I don't know what Fiona's plans are going to be..."