A/N: Okay, so this is my first proper full-length Big Bang Theory fic and I'm all kinds of nervous about it! If you read it and you like, please drop me a review and tell me. It'd really help a lot!

Disclaimer: All recognisable characters belong to Chuck Lorre, Bill Prady, and other folks that aren't me.

Chapter 1 - The Mandarin Theory

Sheldon was so startled by the noise outside his apartment door that it didn't even occur to him to let his fellow hoarders know he was 'AFK' before he threw off his headset and ran for the door. The truth was, the crash of fallen objects was not at all what had him intrigued, after all, many a neighbour was clumsy and stupid and this was not news. What had him all of a flutter and in a hurry was the cursing he heard and the voice which he recognised to be using such unlikely language.

"Penny..." he confirmed his suspicions as he stepped out into the hallway and she turned, still bent over her fallen groceries, to acknowledge him.

"Hi, Sheldon," she sighed, going back to her task, "and before you start to tell me about the condensation on frozen goods and the strength of paper bags, I already heard that one. Six times!" she added after barely a moments pause.

Of course, Sheldon wasn't even listening. He seldom if ever paid any mind to what others were saying when what was going around in his own head was far more interesting and/or superior, which it usually was. This occasion was no different to the norm.

"Penny, did you just curse quite loudly in inadequate and badly pronounced Mandarin?" he asked, still standing in his own doorway and making no moves to help his so-called friend with her groceries, even when she struggle to hold them in her arms.

"Um... maybe?" said the blonde as she stooped to pick up one carton and dropped another in the process, "Ugh!" she made a sound of frustration in her throat as she gave up and let everything fall to the carpet one more time.

"If I may..." began Sheldon as he appeared at her shoulder, startling Penny enough to make her physically jump as she turned around.

She stupidly thought he had come over to help her pick up her groceries but then realised she should have known better when he continued to rattle on, the way only Sheldon could, about her cursing before.

"As far as I can see, there would be only two possible theories for your showing your frustration through badly enunciated Chinese profanity," he told her, holding up two fingers to emphasise his point and completely missing how pissed off Penny looked, even when she folded her arms over her chest crossly and blew her hair out of her face in frustration, "One is that you're trying to learn Mandarin and failing rather badly to master the language. Whilst I thoroughly believe you would struggle with such an undertaking, I see no real reason why you would ever begin such a pointless endeavour," he told her, without a hint of apology for the insult, as usual. "Number two is, whilst unlikely, the only possibility that makes sense, and that is simply that you have picked up these mutilated Mandarin curses through multiple viewings of Joss Whedon's Firefly"

Penny's expression had not changed much throughout his whole speech. Normally she would be bored rigid and completely lost by the end of a one-sided conversation with Sheldon, but the fact was she knew what was coming on this one and had to spend the whole of his long rambling theory figuring out how to answer.

She was a little more geeky than she had been before moving here over four years ago and meeting these guys. She made Star Trek references without thinking, she knew that the Green Lantern's alter-ego was Hal Jordan (although that was really more down to Ryan Reynolds being a hottie than anything else) and she actually found that when there were shows on TV that mentioned physics, she could stand to watch for a while... at least until America's Top Model came on. Yes, she had changed, she had accepted her geek side, small as it was, and the guys knew that, but this she was not ready for. Nobody was supposed to know she was just a little bit in love with the short-lived but much-loved cult classic sci-fi show that was Firefly.

"I... I don't know what you're talking about" she forced out, though even she knew she was less than convincing.

Sheldon saw her flinch before answering, noticed too many signs of stress and irritation to doubt for a moment that she did indeed know just exactly what he was referring to. It surprised him that Penny could have such good taste in television. Usually she went in for the banal, pointless, and utterly annoying reality shows, or any channel on which shoes were sold. Right now she was, as far as he could tell, trying to hide love for a TV series so very close to his own heart. Sheldon might have been moved if he were not too intelligent to over-emote at the slightest thing.

"Really, Penny," he sighed at her ineffective attempts to fool him, "I wouldn't need to be the genius that I am to realise that the shuffling of your feet, the sweat on your brow, and the inability to look me in the eye means that you're lying to me," he said smartly.

Understandably, his neighbour immediately cracked.

"Okay, fine!" she practically yelled, unfolding her arms even more dramatically than she originally crossed them, "Captain Mal is completely badass, Wash is just the most fricken' hilarious guy in the 'verse, I want Inara's clothes so bad it hurts, and I'd kill for Jayne Cobb to look at me the way he looks at his guns," she rattled out, fast and furious, startling Sheldon to no end with both her tone and the facts she was spitting out wholesale, "Happy now?" she asked him finally, before turning and storming into her apartment, slamming the door shut behind her.

Sheldon looked at said door and then let his eyes wander to the groceries all over the hallway still. With a troubled frown he eventually shook his head and rushed towards Penny's apartment.

Knock, knock, knock


Knock, knock, knock


Knock, knock, knock


There was a pause after the third attempt to get her attention and Sheldon fully believed he was going to have to start over with a second round of three sets of knocking when suddenly the door opened again.

"What?" she asked.

"No," he replied, confusing her greatly.

"No, what?" she questioned, and just when the conversation seemed doomed to fall into repetitive ridiculousness, Sheldon did at least have the good grace to stop it and explain.

"You asked if I was happy now, and my answer is no," he informed her, with a purposeful shake of the head that emphasised his point. "My mood might be categorised as confused or intrigued, but at this precise moment, not at all happy"

"What do you want from me, Sheldon?" asked Penny in pure frustration, "Okay, so you found out about one thing that means I have a little bit of a geek side. That doesn't mean I wanna watch your Star Wars Blu-Rays or start collecting comic books or any other pathetic thing that you would do. I just like a little Firefly is all" she said, immediately moving to close the door in his face - Sheldon's foot was faster.

"Penny," he gasped with apparent disbelief, "there is no 'all' about Joss Whedon's Firefly," he told her as he followed her back into her apartment, letting the door go behind him. "It is a complex study of nine, nay, ten characters, since Serenity herself is considered to be just as important to the story as those that seek sanctuary inside her metal walls," he explained, barely even noticing that Penny was growing more aggravated by the second and was resorting to her usual wine bottle. "Plus it is an unparalleled interpretation of a future in which old Western society has been combined with the Oriental, and with technology that far outstrips our own..."

"I know what its about, Sheldon!" Penny snapped as she downed half a glass of wine and immediately filled it back up to the top. "I watch the damn show, that's the point of this conversation, which is now over, bye-bye!"

She encouraged him towards the door with a wave of her arm, though she knew he wasn't gong anywhere. Sheldon didn't let things go, it was not his nature. His nature was to go on and on about a topic until it drove you crazy, and that never took very long - hence the alcohol, though she doubted already that one bottle was going to see her through.

"No, I can't leave," Sheldon told Penny as if she ought to have known it. "You have to tell me how you ever began watching Firefly," he explained as she came to sit down on the couch, wine glass in one hand and bottle in the other. "I mean, I understand that Browncoats are not all particularly sci-fi fans or purchasers of comic books, Firefly had a very wide range of supporters" he considered as he perched on the opposite end of the couch, "but I hardly think the intended demographic was blonde Nebraskan waitresses with a shoe fascination, that look good in short-shorts and abuse alcohol"

"Hey! I do not abuse..." Penny began to say before looking from one hand to the other. "Okay, so sometimes I drink a little too much," she conceded, before her brain caught up with the rest of what Sheldon had said. "You think I look good in short-shorts?" she grinned more than she meant to, only for her friend to roll his eyes.

"Off-topic," he told her with a wave of his hand, almost looking ashamed that he mentioned such a thing. "The point is, since I know Leonard does not have the sense he was born with to be an aficionado of the great Joss Whedon's work, and I have never introduced you to any of my interests or hobbies since the Age of Conan debacle, 2008" he rattled out, "my question remains valid. How did you, Penny, come to find an interest in Joss Whedon's Firefly"

"Okay, first," she began answering him as she parked both her wine glass and the bottle back on the table (after filling said glass again, of course), "you don't have to say the creator's name every time you mention the title" she reminded him. "Second, I found Firefly one time when I was flipping channels and... I don't know, it was interesting," she shrugged. "It had girls in pretty clothes and muscley guys and, excuse me, more UST than most couples in a soap opera!"

"UST?" Sheldon echoed with his rarely seen look of puzzlement.

"Unresolved Sexual Tension," she clarified.

"Oh, amen to that" he agreed without even thinking.

"Anyway, I liked it" Penny continued, "and I must've mentioned it in front of Leonard because the next thing I know he's lending me a DVD boxset"

" But Leonard doesn't have a Firefly boxset," her friend shook his head immediately. "I have a Firefly boxset. Well, actually, I have four, but you cannot borrow any of them," he told her definitely.

Penny opened her mouth to ask why he would need four copies of a DVD boxset but just as quickly changed her mind and didn't bother. The reason would be so ridiculous, she could already imagine it and she so didn't want or need to hear it for real.

"It was a while after we broke up," she explained. "I think Leonard was hoping that being nice to me might get him back into my good books... or at least my bedroom," she rolled her eyes as she scrambled to fetch the DVDs she was talking about from the shelf and presented them to Sheldon. "See, they still have the BuyMore price sticker on, and when he gave it to me, the plastic bag was sticking out of his pocket," she smiled. "I didn't have the heart to tell him I knew he bought them as a gift, because it'd just be awkward, and honestly? I just really wanted the DVDs"

Sheldon probably wasn't listening, he seldom if ever was when people started talking about feelings or anything that wasn't either scientific or at the very least about one of his favourite things. Firefly was precious to him, that much was clear from the way he was holding Penny's DVDs right now, as if they were a Ming vase or something equally as expensive and fragile.

"Finally, a friend that understands," he smiled almost too much for Penny's comfort.

"Sheldon?" she said carefully when his eyes never lifted from the sleeve on the boxset. "Sweetie, seriously, are you having some kind of seizure?" she checked, with sincere worry for his condition.

"I never expected it to be you that understood," he said with glee, finally looking across at her as he spoke, "but you do. A fellow Browncoat, right here across the hall!"

Penny couldn't help but laugh, not at his crazy behaviour like she might usually, but because she was astonished by how pleased he was. Sheldon was like a child that no-one understood or wanted to befriend. By being a fan of this show, one of his ultimate favourites she was sure, it made him feel better, not so alone. He had been that child, she realised then, the one that the other kids just didn't want to be around and had nothing in common with. There was no way she could deny him the chance of sharing something so weirdly important to him with another person, even if it meant spending hours with him rewatching one of her own favourite TV shows.

"You wanna pop in Disc 1?" she offered easily, "I could make popcorn... Okay, I'll go do that" she jumped up fast from the couch when Sheldon suddenly dived towards the TV, fumbling to get the DVDs out of the box at top speed.

It would be several hours and two discs later before Leonard came home to his apartment with Howard and Raj in tow, ready for their evening of take-out and video games, only to find Penny's apartment door not quite shut properly. Beyond it they heard her yelling words that were completely un-Penny-like and then most definitely two voices, both pertaining a Southern drawl...

"And what does that make us?"

"Big Damn Heroes, sir"

"Ain't we just!"

Pushing open the door, the three guys looked in with astonishment at Penny sat lotus style on one end of the couch with Sheldon right beside her, the pair of them so intent on watching the TV and grinning over what was happening that they never even noticed the intrusion.

"That's... disturbing" said Wolowitz quietly, at which Raj nodded.

Before any of the three had a chance to speak again, another quote was being intoned in stereo by the pair on the couch.

"Yeah, but she's our witch, so cut 'er the hell down!"

"Oh, this is more than disturbing" Leonard muttered as he pulled the door closed, leaving Penny and Sheldon to their fun that nobody else could grasp just yet.

To Be Continued...