The Pon Farr Hypothesis

by: Zenkindoflove

AN: This is my first Big Bang Theory fanfiction. This concept is based on many fanon theories from the fandom – mainly centered around whether or not Penny and Sheldon had an attraction to each other in the pilot (which I definitely maintain that they did). This fic is going to be AU starting from the pilot to explore what could have happened. I'll be using S1 as a very rough guideline to get some things set into motion. Also, it's rated M for a reason.

Disclaimer – I do not own the characters of The Big Bang Theory or any situations that might resemble any that occurred in the show. I'm also a neurobiologist in training, so if I'm way off on my physics, I apologize ahead of time. This first chapter is basically the canon version of the pilot, with my own head canon ideas about internal dialogue and motivations thrown in. All of the dialogue is straight from the episode and doesn't belong to me.

Chapter 1

Sheldon and Leonard ascended the stairs of 2311 Los Robles, avoiding discussing their failed attempt to donate sperm at the high IQ bank. Sheldon filled the void with one of his many rambles about scientific inquiries. Today's topic: stairs. While Leonard tried in vain to ignore his genius roommate, as usual he was sucked into the lecture on his disbelief of Sheldon's conclusion. It didn't surprise him that Sheldon supported this claim by citing his own experiment performed on his father during early adolescence. Leonard briefly wondered how much destruction the earth would face if all boys spent puberty the way it seemed Sheldon spent his, instead of doing – well- what they went to the sperm bank to do.

Sheldon hated banal chit chat. But he found in his seven years of cohabitating with Leonard that silence made his roommate uncomfortable and twitchy. And he'd rather educate Leonard on the wonders of the physical world then have to deal with Leonard's tired attempts at making conversation. Sheldon had adapted a new set of behaviors living with Leonard, one of them being his tendency to dominate conversations. Sheldon figured if he had to listen to anyone speak, preferably, it would be himself. And since silence was no longer an option with Leonard, he developed an automatic response to jabber away to fill the void. This particular lecture was one of many he had preplanned that would only take the expanse of the trip from the second to the fourth floor.

As the young scientists reached their apartment, their eyes quickly noticed the strange scene of a new neighbor moving in across the hall. Both were captivated instantly by the blonde beauty, wearing denim shorts and a low cut blouse, unpacking in a sea of large boxes.

"New neighbor?" Leonard questioned.


"Significant improvement over the old neighbor."

Sheldon gave Leonard an exasperated look, "A 200-lb transvestite with a skin condition? Yes, she is."

The blonde woman noticed their presence then and greeted them with a warm smile. "Oh, hi!"

Leonard felt the familiar hum of falling in love that he had experienced many times in his life at the sight of a beautiful girl. Sheldon, on the other hand, was experiencing an entirely new and unnerving sensation that his eidetic memory could not remember occurring in his history.

Her body was aesthetically pleasing. That was obvious to him, and it didn't take her confident exposure of tanned skin to come to that conclusion. But something about her beauty made him nervous, and he found himself reflexively looking down when her eyes found them standing in the hall. As Leonard exchanged greetings with her and he mimicked back, Sheldon couldn't stop his eyes trailing the curves and lines of her body. Her shape would now forever be imprinted in his brain, available for immediate recall whenever he saw fit. Not that Sheldon could think of a time he would need this information. He didn't take the effort to care to consider an individual's sexual appeal like it seemed the rest of humanity obsessed itself with. But something about this woman's presentation had him collecting data over and over and over…

Leonard stating they didn't live together pulled him out of the loop. He was puzzled as to why Leonard would lie to this woman about a fact that would be so clearly obvious to her.

"Oh, no, we don't live together. I mean, we live together but in separate, heterosexual bedrooms."

Sheldon found himself relieved that Leonard thought to mention this to her. This grouping of himself with the rest of heterosexual males reminded Sheldon of his manners. He returned his eyes to his feet, making note that this aspect of chivalry was never something that he had troubled with before.

"Oh, well I guess I'm your new neighbor. Penny."






An awkward silence fell over the group.

"Well, uh…" Leonard tried to think quickly on his feet. "Oh! Welcome to the building."

"Oh, thank you!" Penny cooed at him. "Maybe we can have coffee sometime."





Another pointed silence indicated that the greeting had expired its appropriate length.

"Oh, well bye," Leonard quickly tried to save face.


"Bye." Sheldon mimicked.

"Bye…" Leonard trailed off as Penny closed the door.

Sheldon found solace when their escape presented itself from this confusing conundrum. While he had always been a man who sought answers for the great mysteries of the world, this puzzle made his stomach feel ill, and in that moment, he committed himself to not think of the alarming reactions his new neighbor elicited in him. It was nothing that Battlestar Galactica commentary couldn't chase away.

But Leonard had other ideas. Of course.

"Should we have invited her to lunch?" Leonard asked as Sheldon fished out his keys.

"No, we're going to start Season 2 of Battlestar Galactica!"

"We already watched the Season 2 DVDs."

"Not with commentary."

Leonard continued with this idea as they entered the apartment. "I think we should be good neighbors. Invite her over. Make her feel welcome."

"We never invited Louis/Louise over," Sheldon countered.

"And that was wrong of us. We need to widen our circle."

"I have a very wide circle," he argued. "I have 210 friends on Myspace."

"Yeah, and you've never met any of them," Leonard rolled his eyes.

"That's the beauty of it."

Leonard was fed up with Sheldon's opposition. "I'm going to invite her over. We'll have a nice meal. And chat."

"Chat?" Sheldon yelped. He ran after Leonard. "But we don't chat! At least not offline."

Sheldon found himself frequently annoyed at Leonard's attempts to socialize with those who were to the left of themselves on the bell curve of intelligence. He already could see that Leonard was developing his predictable crush on the woman across the hall.

Penny Marshall smiled to herself as she replayed the strange encounter that just happened with her new neighbors. She was used to men like them responding to her in this way. She preferred their shy, boyish admiration to the aggressive advances of other men. Men like her ex-boyfriend – Kurt. Her heart sank at the thought of him…

Knocking interrupted the thought and she opened the door to reveal her squirmy neighbors.

"Hi, again."



"Hiii." She playfully added. She was kind of loving the awkwardness of these boys.

"We brought home Indian food," Leonard shoved a bag at her. "And I know that moving can be stressful. I find, when I'm undergoing stress, that good food and company can have a comforting effect. Also, curry is a natural laxative, so I don't need to tell you that a clean colon is just one less thing to worry about."

Sheldon shot Leonard a horrified expression. "Leonard, I might not be the expert here, but I think in the context of a luncheon invitation you might want to skip the references to bowel movements."

Penny had trouble keeping up with the fast pace of Sheldon's speech, but she caught "luncheon invitation" and went with it. "Oh, you're inviting me over to eat?"

"Yes," Leonard nodded.

"Oh, that's so nice. I would love to," She accepted their confusing offer to lunch because she really was hungry, and if she were honest with herself, she would rather not be alone right now.

"Well, make yourself at home," Leonard declared as they entered the apartment.

Standing close to him, Penny leaned over his shoulder making sure he understood her gratitude, "Okay, thank you."

Sheldon watched as Penny flirtatiously leaned into Leonard, and he felt a slow burn building in his chest. He watched his friend and roommate nervously respond to the blonde's proximity, and when Leonard turned his eyes to him, Sheldon mocked his awkward reply.

Penny was at a loss for words as she looked around the guys' apartment. Hard wood floors. A swank leather couch. And colorful figurines on shelves that added a sense of innocence to the mature order of the room. But her eyes didn't linger long as soon as she spotted the white board in the center of the room. Penny approached the board with strange scrawl across it that she only could guess was some kind of higher level math that she definitely was never taught in the Nebraska public school system.

"Wow, this looks like some serious stuff. Leonard, did you do this?"

"Actually, that's my work," Sheldon piped up and stalked over to the board. He rambled on about what all of the equations meant, but Penny just couldn't keep up. Her eyes kept dodging from the intimidating board to the man who would barely look at her before, but now was talking wildly with a twinkle in his eye. Penny smiled as she felt a tingle of excitement run through her at the novelty of meeting someone like this. He definitely wasn't like anyone she had ever met before.

"So you're like one of those beautiful mind-genius type guys?" She asked once he was done.

Sheldon was used to being recognized for his genius. People pointing out the obvious always felt… correct. But as his eyes swept over Penny's body again, with her hip cocked and her bright, green eyes shining up at him, the nervousness coursed through him once more, "Yeah."

Penny bit her lip at the adorableness of his reaction to her flirting. She was flirting, wasn't she? Yes, she was mystified a little at the strangeness of this situation, but she didn't anticipate an attraction to someone like this. Whatever, she'll just go with it. Before she could process her reaction, Leonard piped in, pulling her attention to his board.

"I have a board. If you like boards this is my board."

Sheldon could almost feel the proverbial rug being pulled out from under him as Leonard tried to steal the spotlight. So typical Leonard. Whenever a pretty female was around, he had to try and show off his intelligence.

"Holy smokes!" Penny walked over to Leonard's board, her face looking even more impressed than it had with Sheldon's.

Not wanting Penny to foolishly think that Leonard's work was somehow superior to his, he found himself shamelessly sparring with Leonard over the validity of each other's boards. Disinterested, Penny wandered to the couch and sat down, her stomach reminding her it had been a while since she had a decent meal.

Sheldon was taken aback as he noticed Penny perched in his spot. Oh, why did everyone always try to do this? He supposed it had to do with the fact that it was obvious it was the best seat in the apartment.

"Penny," he approached her hesitantly. "That's where I sit."

Penny grinned up at him, patting the spot next to her invitingly. "So, sit next to me."

Sheldon was momentarily stunned. His blood pressure rose at her suggestive tone (of what though, he wasn't sure). "No, I sit there."

Leonard groaned as Penny asked why Sheldon couldn't sit somewhere else. Penny listened carefully, trying her best to keep up with this strange, lanky man's style of speech as he described drafts in the apartment, ability to hold conversations, and something about his neck being distorted. Sheldon's eyes darted around the room as he spoke, not wanting to look directly at Penny who seemed to be a stickler for eye contact – which always made him uncomfortable.

"Do you want me to move?" Penny finally asked once it seemed he was done, concern lacing her sweet voice.


"Just sit somewhere else!" Leonard pleaded with his roommate, wanting this moment to just end before Penny officially wrote them both off.

Sheldon forced himself to swallow his pride and agreed to this insane idea. He gave Penny a shy smile that she returned encouragingly. He found himself searching. Why didn't he just tell this strange woman more forcefully to get up like he would anyone else? He wasn't accommodating. And he certainly never let anyone sit in his spot.

Penny watched in fascination as Sheldon attempted to find another seat. She couldn't understand why it was so hard for him, but was amused all the same. Who was this man? How could he go from one minute talking in some kind of strange, science language she couldn't understand, and the next being totally perplexed by something as simple as finding a seat? He eventually did end up just sitting next to her, but not until Leonard snapped at him again.

The conversation that followed was enlightening for Sheldon. Penny proved to be a totally unremarkable individual in every way. Her career, education status, subscription to hokum ideas like astrology, and emotional instability he typically associated with the opposite sex all contributed to his new notion that Penny was not a person he cared to have any other kind of relationship with that wasn't a distant but cordial neighborly arrangement. He was a bit baffled as to why he was shy and tip toeing around this woman. He didn't want to be rude, but he also couldn't piece together why he felt nervous around her, and even worse, why his eyes kept trailing her exposed skin. In fact, he was acting like Leonard, trying to appease and accommodate a woman based on carnal desires. Sheldon did a U-turn in his mind, wondering where in the world he suddenly even became a victim to such things. He was always so in control and hid that side of himself. He never struggled with it anymore. Not since he was a young teenager. His thoughts trailed to earlier at the sperm bank. Yes, the sperm bank. That must be it. His plans of masturbating to produce anonymous progeny must have stirred up some primitive desire that even homo novus was sensitive to.

As soon as Penny left the couch to have her dramatic moment, Sheldon reclaimed his rightful territory. A new excitement coursed through him as he fully embraced his explanation for the unnerving drives that seemed to have temporary control. No one would be the master to his psyche, not even bewitching blonde waitresses.

And then Leonard offered her their shower.

"Our shower works."

"Really? Would it be totally weird if I used it?" Penny asked.

"Yes." Sheldon stated immediately.

"Nooo," Leonard shot him a worried expression.



"No," Sheldon directed to Penny, growing uncomfortable with the situation unfolding.

"It's right down the hall," Leonard pointed from his seat.

"Okay, thanks," Penny tucked her hair behind her ears. "You guys are really sweet."

Sheldon felt a tightness pull in his groin as Penny skipped away, his eyes lingering on her shorts wrapped around her long, muscular thighs. It was then that his rational, controlling mind somehow disconnected from his imagination and visions of a wet, soapy Penny invaded Sheldon's brain. Her tanned skin glistening from behind their periodic table shower curtain. Her hands trailing over those thighs, climbing higher and higher and … Oh, lord, Sheldon thought. This cannot be happening.

"Well this is an interesting development," Sheldon stood up in a hurry, frustrated, confused, and desperately needing some hydration. All of this was Leonard's fault. Why did he continue to insist on these feeble attempts at mating?

"How so?"

"It has been sometime since we've had a woman take her clothes off in our apartment," Sheldon clipped at Leonard, trying to erase Penny's naked form from his thoughts.

"That's not true!" Leonard walked over to the kitchen as well. "Remember at Thanksgiving when my grandmother with Alzheimer's had that episode?"

"Point taken. It has been sometime since we've had a woman take her clothes off which afterward we didn't want to rip our eyes out," he corrected.

"Yeah, the worst part was watching her try to carve that turkey."

"So, what exactly are you trying to accomplish here?" Sheldon popped the top off his soda.

"Excuse me?"

"That woman in there isn't going to have sex with you," Sheldon gestured towards their hallway.

"I'm not trying to have sex with her," Leonard unconvincingly exclaimed.

"Oh good, then you won't be disappointed."

A little hurt, Leonard needed to know what Sheldon meant. "What makes you think she wouldn't have sex with me? I'm a male and she's a female."

Oh here we go, Sheldon thought to himself.

"Yes, but not of the same species."

"I'm not going to engage in hypotheticals here. I'm just trying to be a good neighbor."

"Oh, of course!" Sheldon didn't buy it for a second. He had seen Leonard half-hazardly go down these paths before. Never willing to fully commit to an idea of pursuing a woman but pining none-the-less.

"That's not to say if a carnal relationship were to occur that I wouldn't participate. However briefly."

"Do you think this possibility will be helped or hindered when she discovers your Luke Skywalker No-More-Tears-Shampoo?"

"It's Darth Vader shampoo," Leonard clarified. A knock sounded at the door. "Luke Skywalker is the conditioner."

Sheldon felt relief for once at the appearance of Raj and Howard at their door. They had an early Steven Hawking lecture, and of course Leonard was trying to shoo them away. Sheldon teased him, outing that he had a "lady" over (since it was his idea in the first place, he stewed). After a round with Howard, doing what Sheldon would consider Howard's only expertise – anticipating coitus with eligible females – the subject of their discussion walked into the living room, covered only by one of their blue towels.

Sheldon quickly averted his eyes, looking down at his feet from the stool he sat on. He tried to concentrate on anything else. Reciting pi, alphabetizing all the Marvel superheroes, but definitely not noticing how short that towel was on her or her tan lines running across her clavicles. Sheldon reassured himself that his nervous tension was due to the taboo of seeing anyone in this state of undress in his apartment. And maybe his previous hypothesis. Fortunately, today was his weekly masturbatory session. That should solve his momentary lapse in suppression.

He didn't engage with Howard and Raj as they discussed the possibility (more like improbability) of Howard achieving coitus with Penny while Leonard helped her in the bathroom. He didn't know if he should find it comforting to see that every male he knew seemed to have a similar reaction to their new neighbor. On one hand, it normalized him with the rest of the male population and gave him a bit of relief at his moment of weakness, but on the other, he held himself in a superior light when it came to base primitive urges. He should not be having this problem at all. And certainly never hold a similarity to Howard Wolowitz, especially concerning this area.

Leonard returned from the bathroom, hands in pockets. "So…" he began, giving them a hopeful expression. "Anyone want to help me get Penny's TV?"

If there was ever a moment he regretted meeting and befriending Leonard Hofstadter, it was now.

Sheldon considered himself a loyal friend. Loyalty was an honorable quality in any man. It's why he went to retrieve Penny's television from her behemoth ex, even though he knew it was a terrible idea. It's what friends did for each other. However, at this point, Sheldon was really reconsidering whether loyalty was conditional in friendship as his naked thighs stuck to the seat of Leonard's car.

As they approached their apartment, Sheldon adopted a defeated attitude. It was obvious that Leonard's motivation for a relationship with this woman – in whatever capacity that would be – went above and beyond rationality. Fighting him would only strain their friendship. He could tell this Penny was going to be trouble in their lives, but he could always adopt a standoff attitude to the buxom blonde. She would only be a mere acquaintance in his eyes. Not a friend. He certainly never wanted to get to the point to be in her debt where pantsing would be involved again.

"Sheldon, I am so sorry I dragged you through this," Leonard apologized again as they climbed the stairs of their apartment.

"It's okay. It wasn't my first pantsing, and it won't be my last."

"And you were right about my motives. I was trying to establish a relationship with Penny that might have someday led to sex."

"Well, you got me out of my pants," Sheldon quipped.

"Anyways, I've learned my lesson. She's out of my league and I'm done with her. I've got my work and one day I'll win the Nobel Prize and die alone."

Sheldon was grateful to hear this sentiment from his friend. "Don't think like that. You won't die alone."

"Thank you, Sheldon, you're a good friend."

"And you're certainly not going to win a Nobel Prize."

They entered the apartment to find Howard showing Penny something on the computer. Sheldon folded his hands trying to hide his exposed underwear.

"We're home," Leonard announced.

Penny turned her eyes to the guys and her heart dropped at the sight of them standing in the apartment without any pants. "Oh… my god. What happened!"

"Well, your ex-boyfriend sends his regards, and I think the rest is self-explanatory," Leonard explained.

Guilt washed over Penny at their pitiful sight with their knobby, pale knees and matching striped socks. "I'm so sorry! I really thought that if you guys went instead of me he wouldn't be such an ass."

"No, it was a valid hypothesis," Leonard reassured her.

"That was a valid hypothesis?" Sheldon scoffed at his roommate's ridiculous statement. "What is happening to you?"

Penny ignored Sheldon's irritation, understanding why he would be so frustrated. She reached out to hug Leonard. "Really, thank you so much for going..." and then Sheldon, "and trying and uh, you're so terrific!"

Penny squeezed Sheldon extra tightly and grazed her hands across his middle as she pulled away. Sheldon tried moving his pelvis away from her sudden burst of affection on his person, but he felt a familiar twitch all the same.

"Why don't you put some clothes on, I'll get my purse, and dinner is on me," Penny offered.

"Really? Great," Leonard replied.

"Thank you," Sheldon looked back at her, feeling a conflicting sense of warmth at her hospitality.

Sheldon observed Leonard's moony gaze after their neighbor, drinking in her figure as she entered her own apartment.

"You're not done with her are you?" He knew the question was unnecessary. Leonard Hofstadter was falling in love, and Sheldon couldn't do anything to stop him.

Leonard raised his head in hopeful pride, "Our babies will be smart and beautiful."

"Not to mention imaginary."

AN2: Thank you so much for reading and please, leave a review and let me know what you think! The next chapter will be posted soon. Hope you guys enjoyed it!