Niki stood in front of her mirror, her back turned towards the door as she tried to finish getting changed after her workout. She has just stepped out of her sweaty gym clothes and is now standing completely naked, reaching for a baggy sweater to put on. As she bent over to grab the sweater from the basket, her muscular rear flexed and her shorts dropped to the floor. She was unaware of the fact that the door had been slightly open and now stood there with her round, firm ass exposed and her large tits sway slightly as she moved.

She let out a little giggle as she straightened up and realized her mistake. "Oh fuck!" She cursed, reaching down to grab the shorts off the floor before quickly sliding them back on. Then she gave a playful smirk over her shoulder, not bothering to turn around. "Hey, don't look if it bothers you so much," she teased lightly, still completely naked apart from the sweater she'd just thrown on.

Whatever, you're such a baby, she thought to herself as she turned around fully, her large breasts swaying lightly again. "Fine," she said with a shrug, reaching behind her back and untying the sweater before letting it fall to the floor as well. She stepped out of her shorts and kicked them aside, standing completely naked in front of her stepbrother Jack once more. Her toned body was accentuated by her muscles and the shadows they cast on her skin; her large breasts pointed upwards while her flat stomach and wide hips made for an alluring silhouette. "There, is that better?" she asked teasingly, hands on her hips.

She smirked as she walked over to the bed and sat down next to him, resting her muscular thigh against his legs. "Come on," she said, "I'm only kidding. You know you don't have anything I haven't seen before." She reached out and pulled the pillow away from his face. "Besides, we're step-siblings; it's not like there's anything wrong with seeing each other naked, right?" He looked unconvinced but didn't say anything, so she leaned forward and gave him a quick peck on the cheek. "See? Nothing to be embarrassed about."

She let out a loud laugh as she straddled his body, her lower stomach resting against his chest. "And what do you think I am going to do now?" She teased, grinning wickedly as he squirmed beneath her. Placing one hand on each side of his head, she guided him closer to her pussy and gave another soft giggle when his breath began to caress the sensitive skin of her entrance. "Go ahead," she said with a mischievous grin, tilting her hips forward slightly. "Have a good sniff."

Her hips shifted restlessly, and she let out a soft moan as he began to lick her pussy slowly. "Mmm, that's it," she murmured, gripping the sheets beneath her hands tightly. Her thighs quivered with every touch of his tongue against her sensitive skin, sending waves of pleasure coursing through her body. She arched her back, giving him better access to her folds as he continued to explore and taste her. "Oh fuck," she breathed, unable to contain the growing need for release building inside of her.

"Harder," she whispered huskily, reaching down between their bodies to guide his head closer to her. Her fingers tangled in his hair as he obeyed, licking faster and more forcefully now, drawing out groans and gasps from deep within her throat. Her body tensed, her breasts rose and fell quickly with each ragged breath she took, their nipples hardening into tight peaks. "Yes," she moaned, "like that." Her hips bucked wildly against his face as the familiar tightness built up inside of her, growing ever tighter with every stroke of his tongue against her swollen clit. Finally, with a sharp cry of release, Niki came, her body shuddering violently as wave after wave of pleasure washed over her.

She collapsed forward onto Jack's chest, panting heavily as she tried to catch her breath. "Wow," she managed to gasp between breaths, "I didn't expect that would happen..." Her voice trailed off into a contented sigh as she wrapped her arms around him, feeling surprisingly close and connected to him at that moment despite their often-rocky relationship.

She laughed softly, her breath tickling against the skin of his neck as she undid the last button on his shirt and slid it off his shoulders. "Oh come on," she teased, playfully swatting him on the chest with one bare arm. "You enjoyed it just as much as I did." Her fingers trailed downward, tracing patterns over his abdomen before moving lower to slide off his boxers in one swift motion, leaving Jack completely naked beneath her.

With a grin, she leaned forward and pressed the tip of one erect nipple against his skin, teasing him with the sensation as she slowly circled it back and forth. "You know what this means," she purred huskily, her hips beginning to rock against him once more. Her free hand moved between them, cupping his now hard cock and beginning to stroke it in time with her movements. "I'm going to have to return the favor..." She let out a soft moan as he shuddered beneath her touch, and she took that as her cue to begin moving faster and more urgently against him.

That only made her laugh harder as she continued to grind against him, her breath hot against his neck. "Oh really?" She teased, the hand not busy with stroking his cock moving upward to cup one of his large breasts, squeezing it gently before tweaking his hard nipple. His moans only seemed to encourage her further, fueling the fire burning inside of her as she moved faster and harder against him. Her other hand moved lower, trailing up his thigh until it reached the sensitive skin just above his knee where it began to massage and caress him as well.

"You like this?" She asked between pants, her voice barely above a whisper now. "Do you want more?" And with that, she increased the speed of her movements, grinding herself against him with a newfound urgency that left neither of them able to hide their growing desire for release any longer.

"Oh?" She raised an eyebrow playfully, her tone teasing as she increased the pressure of her touch even more. "Is that so?" Her thighs trembled with each thrust upward against his growing erection, and she could feel herself slipping ever closer to the edge of release. The knowledge that he wanted this too seemed to only make it better for her; she reveled in the power she had over him, even if it was just in this moment. "Well," she breathed huskily, leaning forward so that their chests were touching as she continued to stroke and massage him, "if you insist..." With one final thrust upward, her body tensed, the orgasm washing over her with such force that she arched her back sharply, crying out his name as waves of pleasure coursed through every inch of her. Her inner muscles clenched around his cock, drawing a hoarse groan from deep within his throat, and then just as suddenly, she relaxed once more, collapsing bonelessly against him with a contented sigh. "There," she panted breathily, burying her face in the crook of his neck, "that should hold you over."

While she laid on top of him and his cock was still inside her pussy, Niki couldn't help but laugh at his protest. "Don't worry," she said between giggles, moving her hips experimentally against him, "I'm not going to let that happen." Her fingertips traced circles on his chest as she continued to ride him gently. "But if you really want me to get off..." She trailed off with a playful smile, giving another experimental thrust upward.

"Oh?" she asked playfully, pretending to be surprised even though it wasn't completely unexpected. "And why do you suppose I let you keep going after you said that?" She paused for a moment before adding with a wink, "Maybe because I knew it would feel too good not to." Her smile grew wider as she held his gaze, letting him know that she was teasing but also enjoying their little game. "Don't worry about me getting pregnant or anything like that," she said dismissively. "I have ways of taking care of it if I really need to."

With a final shudder, her body relaxed fully against his, and she breathed out heavily, still feeling the aftershocks of their shared orgasms racing through her. It had been strange and unexpected but also incredibly enjoyable. Maybe there was something to be said for conforming every now and then... or maybe not. She wasn't entirely sure yet. "Well," she said, sitting up and sliding off the bed, "I guess we should get cleaned up before Mom gets home." Her tone sounded casual, almost nonchalant, but there was still a hint of amusement in her voice. As if they had just shared some sort of private joke together.

She laughed as she walked over to the dresser to grab some clothes. "Well," she said, pulling on her favorite sweatpants and a baggy shirt before turning back towards him, "at least I can say that I know how to have fun." She grinned cheekily at him before throwing another playful wink in his direction. "So what's it going to be?" she teased, taking a step closer to him. "Are you going to keep being such a stick-in-the-mud or are you going to loosen up and join me in the fun every now and then?" Her tone was lighthearted and playful, but there was an undertone of genuine curiosity beneath it.

She paused for a moment, wondering if he would actually consider her offer. And then, just as quickly, she decided that it didn't really matter either way; they were step-siblings after all, and their relationship wasn't like anyone else's. She was confident in who she was, and she could be herself around him without feeling the need to change or conform to his expectations. It was a refreshing feeling.

She laughed out loud at his reaction, shaking her head as he retreated to the bathroom. "You're such a baby," she said under her breath, but there was an undertone of affection in her voice that belied her words. She didn't really mind if Jack wanted to keep being so uptight all the time; it meant more opportunities for her to tease him and have some fun at his expense.

In the end, though, she supposed that was sort of the point between them. They were different in so many ways but shared this weird connection through their parents' marriage. It made things... interesting, to say the least. And while it wasn't always easy or comfortable for either one of them, they had found a way to make it work - at least most of the time.

While Jack was in the bathroom, Niki took the opportunity to grab her phone and send a quick text to one of her friends, recounting their little "encounter" earlier. She didn't mention any names, of course; that would be too easy for him to figure out who she was talking about. But still, it felt good to have someone else to share her amusing experiences with, even if they were just through text messages.

As she waited for Jack to finish in the bathroom so they could get changed again and head downstairs, she continued to browse through social media on her phone. It was strange how things worked sometimes; she'd never expected that they would ever be so close like this, even if it was just in this weird, twisted way. But then again, she supposed stranger things had happened before... and probably would happen again soon enough.

While waiting in the living room for her mom to get home, Niki continued flicking through social media on her phone. She couldn't help but feel a strange mix of amusement and embarrassment thinking back to their earlier encounter. It was like they'd switched roles somehow; she usually was the one teasing him and making him uncomfortable, not the other way around. But then again, she supposed that was just how things worked between them now.

A part of her wanted to go into his room and see if he was feeling okay after everything that had happened, but another part didn't want to give him the satisfaction of thinking she cared. So instead, she settled for glancing at the door every now and then, silently willing him to open it or even just peek out so they could resume their usual banter.

The moment her mom finally walked through the front door, Niki's attention snapped back to reality, and any thoughts about Jack vanished like they'd never been there in the first place. "Hey Mom," she called out cheerfully as she tossed her phone onto the coffee table and stood up, ready to face whatever mood her mom was in today.

"Hi sweetie," her mom replied with a tired smile as she walked into the living room and kicked off her shoes. "How was your day?" She asked, not really expecting a long answer. After all, Niki usually didn't volunteer much information unless she wanted to talk about something specific.

"Fine," Niki said with a shrug. "Jack's still in his room, by the way." She paused for a moment, debating whether or not to bring up their earlier encounter but decided against it; it probably wouldn't end well if she did. Instead, she switched topics. "Did you need help with anything?"

Mom glanced over at the door to Jack's room and raised an eyebrow before looking back at Niki. "No thanks," she said with a small smile. "I think I've got everything under control for now." She paused for a moment, studying her daughter's face. "How about you? Do you want to do something special tonight?"

Niki shrugged again. "I don't know," she said honestly. "There's not really anything I feel like doing in particular. We could watch a movie or something if you want." She glanced over at the TV, trying to sound more enthusiastic than she felt.

"Well, we don't have to do anything if you don't want to," her mom said with a understanding smile. "Sometimes it's nice just to relax and unwind, you know?" She walked over to the kitchen and began rummaging through the cabinets, humming to herself as she searched for something.

Niki sighed, leaning against the back of the couch. "I guess," she murmured absent-mindedly. She wished there was more they could do together, but their mom always seemed to be busy with work or other responsibilities. Sometimes it felt like they were both just going through the motions, living in each other's shadow without really connecting on a deeper level. But Niki didn't know how to change that, so she pushed those thoughts aside for now and focused on the present moment.

"Here," her mom said, emerging from the kitchen with a box of cookie mix. "Why don't we make some cookies tonight? It'll be something fun to do together." She held up the box, her expression hopeful.