Jane and Naomi weren’t just sisters; they were best friends. They were the kind of sisters who borrowed each other’s clothes without asking, stayed up late gossiping about boys, and shared inside jokes nobody else would understand. Between their perpetual closeness, their bright red hair, and their similar smiles, strangers often asked if they were twins.

Naturally, when Naomi started college, Jane was excited to learn all about it. Being a year younger meant that she’d be headed there soon herself, so she often barraged her sister with questions about what to expect. Naomi was usually more than happy to share. But this morning, Naomi had seemed preoccupied with something, and the girls ate their cereal in silence. After a few minutes, Jane noticed Naomi staring at her, her eyes distant. When she couldn’t take it anymore, the girl spoke up.

“What?”

“What do you mean, ‘what?”

“You’re staring at me.”

“Oh, sorry,” Naomi said, her cheeks blushing as she picked up the spoon from her bowl of cereal and brought it to her mouth. “Just thinking.”

“About?” Jane asked, looking across the breakfast table.

Naomi set her spoon down, giving her little sister an appraising look. “Don’t worry about it. I don’t think you would do it, anyway.”

Jane crossed her arms. “Do what?”

“Seriously, it’s no big deal. Just forget about it,” Naomi insisted.

Jane scowled. “Come on, Naomi! You can’t leave me hanging. Just tell me.”

“Fine,” the older girl sighed. “I was going to ask if you’d be willing to help me with my psychology experiment, but seriously, I don’t think you’d be interested.”

Jane’s eyes lit up. “Are you kidding? I’m in! Tell me more.”

“Well, if you insist,” Naomi chuckled, “I’m doing an experiment on how pheromones affect thoughts and emotions. The plan is that I’ll have the same interaction with you every day, but every day, I’m going to increase the pheromone load that I’m wearing. I’ll chart our reactions and ask you a couple questions. What do you think?”

“Honestly? It sounds kinda fun,” Jane replied. “So, what kind of interaction are we supposed to have every day?”

Naomi blushed once more. “Okay, that’s the thing. As I was coming up with ideas on how I could test this, I kept coming back to the same idea. It seemed like the best way to do this, but it’s also the reason I don’t know if you want to do this.”

“Come on,” Jane said, “just spit it out.”

“Fine. You have to kiss me.”

Jane stared at her sister. “What?”

“I know, I know! The thing is, pheromones are supposed to affect arousal centers of the brain, so I needed something that would allow me to gauge that. Personally, my hypothesis is that pheromones don’t actually do anything, so I thought this would be the best way to prove that. It wouldn’t be anything sick, just a kiss on the lips for like two seconds.”

“On the lips even? Seriously?”

“I get it,” Naomi said. “That’s why I wasn’t going to ask you. You can back out if you want. Maybe I could see if Mom or Dad would volunteer. It just has to be someone that doesn’t have any sort of romantic attraction to me, and I need to be sure I can see them every day. That’s why I thought of you.”

Jane stared at her sister, considering the offer. “How long is this experiment supposed to last, anyway?”

“I need to have the report written and turned in by the end of the semester, so probably thirty days at the maximum.”

Jane stared across the table at her sister. After a few moments of silence, she let out a sigh and shrugged her shoulders. “Okay, fine. But if this thing gets weird, I’m dipping out.”

Naomi grinned. “It’s a deal!”

After breakfast, the girls went up to Naomi’s room. Naomi grabbed her notebook and pen, opening it up and writing a couple things down.

“Okay, so this is day zero, the control day. This is how I’ll be applying the pheromones I ordered,” she continued, holding up a perfume bottle. “I haven’t added any to the perfume yet, but each day I’ll add a little more, and I’ll keep track of your reaction and responses. Ready to go?”

“As ready as I’ll ever be,” Jane replied.

Naomi took the perfume and sprayed a little onto her skin. “When I add the pheromones, I’ll have to let it absorb into my skin for a while. For now though, I just want you to be familiar with the scent of the perfume. Now, we need to kiss for at least two seconds, and then I’ll ask you a couple questions, okay?”

“Two seconds, period,” Jane laughed. “No ‘at least’ here. I’m ready.”

Naomi and Jane looked at each other, doing their best not to giggle at the absurdity of it all. Before she could chicken out, Jane leaned in, pressing her lips to her sister’s and counting out in her head. The instant two seconds passed, she pulled back.

“Okay,” Naomi began. “For the first question, I want to know your level of arousal, with one being completely unaroused and ten being as turned on as you’ve ever been.”

“Solid zero,” Jane laughed.

“Yeah, same here,” Naomi agreed. “But since the scale has to start at one, that’s what I’m writing down. Now, the second question. During our kiss, what were you thinking about?”

“I was counting the time and thinking about how weird it was to be kissing my sister on the lips,” Jane replied.

“Yup, same here,” Naomi said as she jotted down the note. “And that’s all I need. See you tomorrow!”

The girls parted ways, getting ready to head to their schools.

Over the next few days, Naomi and Jane continued the experiment. Every morning, Naomi added a few drops of the pheromone to her perfume, applied it to her neck, and tracked down her sister. Every day, the answers were basically the same as the control.

On the fifth day of the experiment, Jane was in the living room reading a book when Naomi found her.

“Ready for day five?” Naomi asked.

“Yup! Let’s get it over with,” Jane smiled, setting down her book and rising to her feet. As she drew closer to her sister, she picked up the now-familiar scent of her perfume. It really was a nice scent, Jane thought to herself as Naomi flipped through her notebook. She wasn’t into girls, but she could definitely see a guy falling for a girl wearing Naomi’s perfume.

When Naomi was ready, Jane leaned in, inhaling as she brought her lips to her sister’s. For the first time since the experiment began, Jane found herself closing her eyes as their lips pressed together.

As the two seconds passed, Jane decided that Naomi’s lips felt nice against hers. Not in any kind of romantic way for sure, but they were soft, softer than her boyfriend’s. When their kiss ended, Jane backed away slowly, making eye contact with her sister.

“Well, was it another zero?” Naomi asked, reaching for her notebook.

“Actually,” Jane said as her cheeks turned red. “I got thinking about my boyfriend, so it was probably, let’s say, one and a half.”

“Interesting,” Naomi said. “I kind of had a similar experience.

Over the next few days, Jane found her arousal slowly creeping upward. On day seven, she found herself thinking about the last time she made out with her boyfriend. Without hardly thinking about it, she found the kiss lingering just a touch longer than the usual two seconds as a result, and the rating went up to a solid two. By day nine, the rating bumped up to two and a half, with Jane thinking of the last time she let her boyfriend go down on her. On day eleven, the rating was a three, with the sisters’ lips pressed together for at least five seconds before they reluctantly separated.

Then came day twelve.

Jane had been down in the kitchen, looking for breakfast, when her nose picked up the unmistakable scent of Naomi’s perfume, flowery and sweet, with a subtle fragrance she couldn’t quite put her finger on. Almost immediately, she felt her arousal begin to build in anticipation. Not for her sister, she reminded herself. She was only excited because she always seemed to be thinking about her boyfriend during these sessions lately.

Jane took a deep breath, savoring the scent as she turned to find her sister walking through the doorway. Naomi had picked out a cute white tank top and some cutoff denim shorts that hugged her ass. Jane couldn’t help but admire her in the outfit.

“Hiya, beautiful,” Jane said with a happy sigh.

“Hey, sissy,” Naomi smiled back, her eyes momentarily dipping down to Jane’s cleavage. “You look pretty cute yourself.”

“Thanks,” Jane replied, glancing down at her off-white top and faded jeans. “Just trying to look my best. I’m going out with Brad tonight.”

“Lucky guy,” Naomi grinned.

“Especially if this experiment gets me going like it did yesterday,” Jane admitted. “Last night when I was talking to him on the phone, I might have gotten a little carried away.”

“Oh yeah?” Naomi said. “I can’t wait to hear all the details. But first, let’s get today’s experiment in the books.”

Naomi stepped up to her sister, and for a second, they just stared into each other’s eyes. Jane found thoughts of her day slipping away. Her upcoming school day. Classes and friends. Even her planned date with Brad all seemed to fade into the background as she breathed in the intoxicating scent and stared into her sister’s deep, beautiful green eyes. Without giving it much thought, she found her eyes fluttering shut as she tilted her head, bringing her lips to meet her sister’s.

As their lips met, Jane felt her arousal climbing significantly. Why wouldn’t it, though? Naomi was beautiful. No, more than that. Naomi was sexy. Yes, Jane realized, Naomi was truly a sexy woman. She was tall, slim, and so perfectly attractive. Every time she walked in a room over the last few days, Jane found herself just staring as her fragrance filled her nostrils. And now, here they were, lips pressed together once more, just as they had been for nearly the last two weeks. Just as they would be for weeks to come.

Their kiss lingered, and Jane felt Naomi’s hand come up and land gently on her arm. Something about her sister’s delicate touch excited the young woman. It was so sensual, so loving. It was like the way Brad touched her after they made love. Without giving it much thought, Jane found her lips beginning to part as the girl let out a little moan.

Before she could give it any thought, Jane’s tongue tentatively shifted, moving toward Naomi’s mouth. Naomi reacted in kind, and their tongues met for the first time. Sparks immediately went off, and almost instantly the gentle kiss morphed into something new. Something hot. Something sexy. The mandatory two seconds now long since passed, Jane and Naomi moaned into each other’s mouths as their tongues danced, playing off one another as their lips pressed into each other like lovers, not sisters.

As their kiss continued, Jane didn’t care about the experiment. She didn’t care that she was straight. She didn’t even care that she was making out with her own sister. All Jane cared about was the way she was feeling as she received what was without a doubt the best kiss she’d ever experienced.

Somehow, the two managed to break apart. They blushed as they looked at each other, both girls feeling the same unmistakable arousal. Jane tried to play it off, rating her arousal at a six, but in her heart, she knew it had been higher than that.

It wasn’t until Naomi had left the room to go finish getting ready for classes that the reality of what they’d done hit Jane.

“Oh my God,” she muttered out loud, a sense of shock washing over her. Had she really done that? Had she really just made out with her older sister? Jane sat down at the table, processing her thoughts. Sisters don’t kiss. Not like that. Surely, there had to be some logical reason why she’d react the way she did. She felt the same way Naomi did—pheromones were nonsense. There had to be some other reason she felt the way she did. Was it because she was turned on thinking about her date that night with Brad? Was it because she hadn’t gotten off in over a week?

Just then, Jane picked up the scent of her sister’s perfume. Inhaling deeply, she turned to see Naomi entering the room once more. As their eyes met, Jane thought of another possibility. Was it because she was falling for her sister? After all, she thought, Naomi was so beautiful, and for nearly the last two weeks she’d been kissing her every day. That’s got to rub off on a girl, she thought almost dreamily, staring as her sister drew closer.

“Hey,” Naomi said.

“Hey,” Jane echoed.

“I’m heading off to the university. I just… I wanted to say thanks. You know, for helping with my experiment. I really enjoyed it.

“Yeah,” Jane purred, rising to her feet and embracing her sister. “Me, too.”

As Naomi’s perfume filled Jane’s nostrils, the girl found herself looking back into her sister’s eyes and smiling. Without thinking, she closed her eyes and brought her lips back to Naomi’s, and for the first time since the experiment began, they kissed for the second time in a day. After their kiss, both girls blushed, and Naomi practically raced out the door. Watching her ass as she left, Jane tried to clear her head. She couldn’t really be falling for Naomi, could she? She’s her sister, Jane thought. It’s not possible, period. She just needed to get laid, she told herself. She’d go out with Brad tonight, and that would fix everything.

That night, Brad picked Jane up at six o’clock. He was the perfect gentleman, taking her out to dinner at her favorite restaurant. Even so, for reasons she couldn’t quite pinpoint, her heart just wasn’t in the date. It just felt like something was off. Maybe it was because his cologne smelled wrong to her. Maybe it was because of how rough and abrasive his lips felt when they kissed. Maybe it was because every time she looked into his eyes, all she could imagine was that moment of closeness she shared with Naomi earlier in the day.

Naomi. Just thinking about her brought tingles to her spine. The way she smelled. The way she kissed. Jane found herself growing more and more aroused as thoughts of her sister ran through her mind. “Cut it out,” she thought. “Brad should turn you on, not Naomi.” Still, despite her best efforts to focus on her boyfriend, thoughts of her sister kept popping into her mind, pushing her arousal higher and higher.

At the end of their meal, Brad noted that she seemed distracted, asking her if everything was okay. She assured him it was. She decided not to share that all she’d been thinking about throughout their meal was her sister.

“What next?” he asked as he paid for the meal. “There’s a new comedy out at the theaters. Maybe we should head there.”

“Or maybe we should head back to your place,” Jane suggested. “Honestly, I’m really horny, and I think I just need to get fucked.”

Brad’s eyes quickly shifted from shock to excitement as a grin spread across his lips.

Twenty minutes later, they were back in his room, naked and in bed. As Jane stared into Brad’s eyes, a small voice kept reminding her of Naomi. She tried to shake loose the thoughts, but even as Brad started kissing her, Jane couldn’t help but compare Brad to her sister. Brad was so much more abrasive in his style. Naomi had grace. She had soft lips. She had sexy curves. Just thinking about her was getting Jane more turned on than the way Brad was sloppily kissing her.

Sex turned out to be short and disappointing for Jane. The entire time Brad was on top of her, Jane found herself thinking of her sister. She did her best to put on a good show for Brad’s sake, but she was honestly relieved when he finally came. As much as she’d hoped sex would help clear her mind, all it really seemed to do was muddy the waters.

The following morning, sunlight streamed through Jane’s curtains, gently waking her from a dream about Naomi that could only be described as erotic. In the dream, Naomi had come to her for their daily kiss. The kiss quickly turned sexual, with Naomi’s hands roaming up and down Jane’s body. Soon the women were naked, with Jane panting as Naomi lowered her head down between Jane’s legs, lapping at her soaking pussy.

Jane tried to shake off the imagery of her dream. “Come on, girl,” she mumbled to herself. “That’s your sister.” In spite of her best efforts though, all she could see every time she closed her eyes was the vision of Naomi between her legs, naked and eating her out. Deep down, Jane knew what she needed to do. She needed to end the experiment with her sister. She needed to get a little space between them for a while so she could clear her head. She needed to get back to loving her sister, without lusting over her.

Just then, there was a knock at the door. Jane scrambled, sitting up in her bed as the door creaked open. As soon as it did, the scent of Naomi’s perfume filled Jane’s lungs. Jane found herself smiling. She really did love that fragrance.

“Happy Saturday,” Naomi purred, smiling at her sister and taking a step into the room. “Did I wake you?”

“Oh, no,” Jane replied, her eyes drifting down to her sister’s nipples poking through her tank top. “I was just… thinking. Where are Mom and Dad?”

“Mom’s getting her hair done and then going out with Mrs. Clark for the afternoon, and Dad’s out trying to get one more fishing trip in before it’s too cold,” Naomi smiled as she sat down next to her sister in the bed. “It’s just us until dinnertime. So, what were you thinking about?”

“I—um,” Jane stuttered, the fragrance overriding her thoughts. “I was just…”

Before Jane could form her words, she found herself interrupted by Naomi leaning in and planting a kiss on her lips. Jane’s eyes went wide. This wasn’t how it was supposed to go. She was going to back out of the experiment, not kiss Naomi again. Her mind screamed to back off, to push Naomi away. To tell her this had to end. But even as these thoughts went through her mind, her body was reacting entirely differently. Her arm came up, not to push Naomi away, but to trace her finger up and down her exposed arm. Her lips moved, not to tell her sister to stop, but to part so their tongues could meet once more. Even her legs shifted in the bed, not to make room between them, but to allow Naomi to move closer.

Soon, Jane’s eyes fluttered shut again as her objections eroded and she melted into the kiss.Their tongues pressed against each other, and little moans and whimpers escaped their lips. Jane’s arms wrapped around her sister, and one by one, her objections began to vanish.

Much to Jane's chagrin, Naomi broke off the kiss just a few seconds later. “Oh my God,” Naomi said apologetically. “I’m so sorry, Janey. I just—I just don’t know what came over me. I was just looking at you, and I just, I…”

This time it was Jane’s turn to silence Naomi. Fueled by memories of her dream and the intense arousal she was feeling, Jane grabbed her sister, pulling her lips back into her own. Almost immediately, both girls began moaning into each other’s mouths. Jane pulled on Naomi, and the girls fell back into the bed as their kissing intensified. Naomi’s hands landed on Jane’s torso, moving slowly upward. Jane gasped through the kiss as she felt one of her sister’s hands tentatively cupping her left tit. It felt so good. Everything felt so good.

“More,” Jane groaned between kisses. “Please, more.”

Naomi obliged, her hands roaming all over Jane’s breasts, massaging them, fondling them, eliciting moans from her little sister. Jane reciprocated, tugging at Naomi’s tank top. Naomi shifted, letting her sister slip the garment off and drop it to the floor. Jane’s top followed soon after, leaving the girls in nothing but their pajama shorts.

“Oh, yes, Janey,” Naomi groaned as her sister kissed her neck, trailing kisses up toward her earlobe as her hands roamed up and down her body. “Yes, so good.”

As the girls made out, Naomi rolled, pinning Jane beneath her. Their lips reunited, their tongues intertwined as Naomi lay on top of her sister, their tits mashed together as they groaned for more. Slowly, Naomi broke off the kiss, kissing Jane on her cheek, then her neck, then trailing kisses down toward her breasts. Jane’s hands moved to Naomi’s head, her fingers running through her sister’s red hair.

“Fuck,” Jane moaned as Naomi’s lips found her nipple. “Oh, Nay, that feels so nice.”

Naomi wasn’t done. She continued kissing, working her way lower and lower, planting kisses on her torso, then her navel, then right at the waistband of her shorts. Jane instinctively raised her hips, allowing her sister to tug her shorts down and off, revealing her glistening pussy.

“I dreamed about this,” Naomi breathed, her eyes locked on her sister’s wetness. “It was so good.”

“Me, too,” Jane moaned, feeling her sister’s breath on her pussy lips as Naomi was drawn in.

In a heartbeat, Naomi moved down, extending her tongue and giving her sister’s slit a long, slow lick. Jane groaned, spreading her legs wider, inviting her sister in. Naomi took the invitation, licking at her sister once again, parting her folds with her tongue. That lick was followed by another, then another. Soon, Naomi was eagerly licking her sister’s slit over and over, lapping up her juices. Jane cried out. The smell of her arousal mingled with the perfume, driving her passion even further.

Then, just as Jane thought it couldn’t get any better, Naomi shifted again, her tongue pressing up against her clit.

“Fuck!” Jane cried as her sister began working her clit with her tongue. “Oh, yes. Fuck, don’t stop!”

Fueled by her sisters’ words, Naomi dove in, eagerly flicking and sucking her sister’s clit. As she did, her hands went to work, one hand reaching up and groping Jane’s tits while the other pressed a manicured finger inside her sister, slowly finger-fucking her as she continued flicking Jane’s clit with her tongue.

Jane writhed in the bed under her sister. She was in absolute heaven. She moaned and groaned, begging Naomi to give her more, to make her come. The tiny voice telling her that this was wrong, that she shouldn’t be fucking her own sister, had fallen completely silent. In its place, a new voice spoke out, a voice desperate for more. A voice that wanted this to go on forever, to fuck and be fucked by Naomi. Brad didn’t matter. She didn’t care that she was cheating on her boyfriend of three years. She didn’t even care that she was cheating on him with her own sister. All Jane cared about was the pleasure Naomi was bringing her. Pleasure they could share anytime they wanted.

“Oh, fuck,” Jane moaned out as her sister’s tongue continued working its magic. “I’m close. I’m so close. I’m gonna, oh, I’m, oh! I’m coming!”

Jane’s hands locked on to her sister’s hair, holding her in place as her body began convulsing from her orgasm. She screamed out at the top of her lungs, feeling every atom in her body shudder with pleasure as jolt after jolt of pure delight pumped through her. She pressed her hips up and into Naomi’s face, crying out as she rode out the single biggest orgasm of her life.

When she finally came down from her orgasm, Jane released her grip, her eyes looking deep into Naomi’s. The girls smiled at one another with a knowing smile. They both knew that this wouldn’t be the last time this happened. It probably wouldn’t be the last time today. Naomi gave Jane’s pussy one final, slow lick, then crawled up, bringing the girls’ lips together once more. Jane relished the taste of her orgasm on her sister’s lips. Like everything else, it was so sensual. So perfect.

“So,” Naomi said, smiling softly into her younger sister’s eyes. “What now?”

“Now,” Jane grinned, “I think it’s your turn.”