I do not own any of the characters from the show Big Bang Theory. The concept for this is entirely mine though.

I'm going to warn you now, this is an OT3 fic. As in three people engaging in a relationship/sex. If you have issues with sex involving three persons, skip step 4 or hit the back button. You were warned in summary.

Step 1: Ask a question

"Did you and Sheldon ever, you know? Before I moved in?" Penny stared over at the brunette, chopsticks poised in what Leonard would consider 'sexy' and he nearly choked on the clump of rice in his mouth. Her perfectly styled eyebrows wiggling in a way that totally said what Leonard thought she was saying while her lips were pursed coyly.

"What? Where did you get an idea like that? Did Howard say something?" Leonard babbled quickly, taking a sip off his juice box as Sheldon walked into the kitchen from the hallway.

"Did they wear gloves when they prepared this?" The taller physicist asked as he uncapped the plastic take out container.

The conversation ended there, but based on Leonard's reaction, Penny could safely say she'd gotten her answer.

Step 2: Do Background Research

If A = B and B = C, then C = A. So if A is attracted to B and B is attracted to C, can C be attracted to A?

"So, how many times did you guys do it? Or was it on a regular basis?"

"Penny, where are you getting these ideas from?" Leonard looked up from his work desk, busy fixing the 'A' key on her computer, yet again, "You really need to stop spilling stuff on your laptop, it's going to break one of these days."

Penny frowned, "You aren't denying the fact that you and Sheldon have done the deed."

Leonard flailed slightly, the 'A' key popping off as his face went white, and then a rosy blush curled in his cheeks. Penny fished around on the floor for the missing piece of plastic, and dropped the subject.

~*~

Penny never denied the attraction she had for Leonard, in her mind that is. His social ineptitude and her social need to engage in sex with men that almost always made her feel inferior towards the end of the relationship kept her from ever admitting it out loud. She only spoke it openly to her cousin back in Nebraska over a phone call one day, and even that ended with her getting angry and throwing the phone across the room.

When she almost ended up sleeping with him that one drunken afternoon, even though it ended before it began, she began to study him, watching how he moved with such an, ease. How could such an awkward boy, here she ended up correcting herself for he was a man, move so gracefully. He was handsome, not the same chiseled way that she was usually attracted to, but in the way that she knew he'd always look that nice, even when he was 30.

She never would have guessed that there was a distinct possibility that she wasn't the only person in the apartment building who looked at him the same way.

"The condom supply in their bathroom is low, guess that means they've been going at it like Tribbles in a cargo bay." Howard walked back into the living room from his trip down the hallway.

"Like what?" Penny paused the Halo 3 match she was having with Raj.

"You know, like two gay penguins trying to make an egg." The brightly dressed man wiggled his hips as he spoke.

Penny shook her head, trying to rid the image from her mind before opening her mouth, "Are you saying Leonard and Sheldon," She emphasized the second name, "have been having sex?"

Raj looked over at her, eyes wide as he nodded his head quickly while Howard smirked at her, "Penny, Penny, Penny, before you moved in, Leonard didn't have many options, and Sheldon, well, he's Sheldon."

Penny cocked her head to the side, and began pondering it, she unpaused the game and threw a frag grenade at Raj.

~*~

After that conversation Penny caught herself staring at Sheldon. At first she thought she was just trying to see why Leonard would even want to engage in sex with him, but then she began noticing how his little quirks, such as knocking on her door in between saying her name exactly three times or attempting to understand sarcasm, were oddly endearing, almost cute. One time, she caught him staring at her, and she reached up and touched her hair nervously before stuffing a fry in her mouth.

It might have been two months after her afternoon conversation with Howard where it all clicked in her mind. However, it clicked during Chinese takeout night and Penny froze in between a bite of her General Tso's Tofu. She had been snatching glances at Leonard and Sheldon all evening, and she finally realized the undeniable pull she felt towards them.

"Oh, my, GOD!" It was a cry of disgust, more with herself for not realizing it, than it was for liking both of them.

The shriek startled the four nerdmigos, Howard jumping slightly when she threw the container onto the coffee table. He barely moved out of the way as she stormed by him, heading for the door.

"P-Penny, what's wrong? Did they give you chicken again?" Leonard began to get out of his seat, putting his own food down.

She stopped, turned, pointed a finger and opened her mouth but paused before opening the door and crossed the stairwell only to slam her own door.

"What just happened?" Sheldon asked a moment later, while the other three remained silent.

Step 3: Construct a Hypothesis

Penny began planning a week later, after the shock of liking both of the boys next door wore off. She didn't want to lose either of them, she knew the best bet was to start with Leonard first, but he would be reluctant to involve Sheldon, especially since he could barely talk about the other man around her anymore without a blush on his face.

Sheldon would be harder to get involved with though, he didn't particularly enjoy human contact. Though, he'd be more likely to involve Leonard, a security blanket of sorts.

Penny smiled devilishly at the soda fountain before taking the drinks to her table. The plan was set in her mind, and all she had to do was wait until later when she was finally cut and allowed to leave before the plan could go into motion.

Step 4: Test Your Hypothesis by Doing an Experiment

Penny opened the door to the boys' apartment and saw Sheldon sitting on the couch, in his spot, watching television. He grabbed the remote and paused Battlestar Galactica, "Leonard isn't here, Penny."

"That's fine," She went up to him, stood in front of him, and leaned down, "I think this will work better anyway."

"She kissed him, full on the lips, and almost smiled when the expected non-responsive lips made a noise of confusion/protest. What caught her off guard was Sheldon opening his mouth for her, letting her explore openly as he began to respond to her sudden Frenching. She hiked her skirt up slightly and straddled his lap, her hands steady on his shoulders, keeping her from falling off. Sheldon hesitantly placed one hand on her smooth thighs before realizing 'holy shit, there is a beautiful woman making out with me' and the other hand went to her hip, sliding down to her butt. His finger pads pressed lightly into the cheap polyester of her skirt, not quite grabbing her, but not resting there either.

"What the hell?" Came the indignant squawk from the front door, Leonard dropped his keys to the ground and stared at his roommate/sex-buddy and the girl he'd fallen in love with the moment he first laid eyes on her, "What's going on?"

Penny looked up, her lip gloss smeared and hair mussed, "Oh."

Sheldon's t-shirt had been stripped off, as had Penny's yellow sweater vest, both were on the floor around them. Penny's white blouse had been unbuttoned completely and Sheldon's thermal was pushed up around his chest.

"I'll just, go to my room." Leonard had the combined look of having his world shattered and being scolded by his parents.

"Oh no you don't." Penny got up, stumbling slightly over the coffee table, Sheldon's hand only barely catching hers as she reached out to balance herself.

Leonard had already been going for his room so Penny had to avoid his chair in order to get over to him and pull him in for a kiss. He didn't bother to respond to her moving, eager lips causing her to pulling away, her pretty face contorted in desperation.

"Don't be- Leonard- come on, please," She went from anger to annoyed to breathy and begging in 4 seconds, the last word whispered against his lips as she pecked against them lightly, "Please Leonard, please."

Their lips met again, their second kiss being tender and passionate before it quickly became rough and arousing. His hands moved to her hips and pulled her in close, causing her to grind her hips dryly against his. Her hands ran through his auburn hair, tangling it in her slender fingers. They pulled away, panting harshly from all the activity. He rested his forehead on hers the frames of his glasses bumping against the bridge of her nose.

"Oh, these have to go, now." She pulled back and brought her hands up to his face and removed them. He laughed as she tossed them, hitting something metallic behind them.

"Did they land in the sink?"

He rested his head in the crook of her neck as he heard her giggle before blond hair brushed his face. She had turned her head and body slightly to look at Sheldon.

A look up at the taller man said everything and Leonard reached for him, grabbing his green thermal in greedy fingers before pulling him straight up against Penny's back. Sheldon looked down at the shorter scientist before Leonard's hand abandoned its position on Penny's hips and grasped the back of Sheldon's head. He was pulled in for a kiss that caused the three to rock against each other, sending sparks through Penny's mind as she felt Sheldon and Leonard.

Penny moaned, a deep noise pulled straight from her gut, as she was pulled closer to Leonard and Sheldon pressed against her back, "Oh, oh, boys, bedroom, now."

The two men ignored her as Sheldon's large, spindly hands grasped at the sides of Leonard's face, one burying into the thick auburn hair right behind the ear, the other holding his face close. They pressed closer, squishing the woman between them as they lost themselves; mouths open with tongues fighting for dominance. The blond pressed tiny little kisses to the left side the brunettes chin, pecking lightly at Sheldon's fingers as she came to them. She gasped as one of Leonard's hands ghosted over her breast, and she pressed her hips flush to Leonard's, Sheldon's pressing into her backside.

Oh, C could definitely equal A.

A smaller hand, bigger than her own, but still smaller than Sheldon's, grasped at her left side, holding her close as Leonard pushed as close as he could, relishing in the sweet frictions that were created through the light denim of his jeans.

Eventually they tumbled into Leonard's room, Sheldon's rule still in place even with the promise of mind blowing sex, and Leonard's bed was bigger. Sheldon brought the box of condoms with him, a fresh box with a new tube of lube, non-scented and water soluble. Leonard pulled at the zipper hidden in the back of Penny's skirt before she shooed his hands away.

"Don't break it," She kissed him as it went down successfully. Leonard grabbed the yellow material and she shimmied her hips as he pulled it down, "Shelly, he's wearing too many clothes."

Sheldon made a small chirp like noise in his throat before he pushed Leonard off of Penny and began to unbutton the dress shirt. The pants soon followed, thrown to the floor to be remembered later. After Sheldon had squirreled off the powder blue boxers Leonard pulled him close, groins bumping as Sheldon intentionally hovered above him. Penny grinned and began kissing Leonard's hand, sucking on his fingers briefly.

"Guys, I - " Leonard continued to grind up into Sheldon's pelvis, frantic in his movements.

Penny bent down to whisper into his ear, "Let go," before biting his earlobe.

He did, he arched his back, rising off the mattress, mouth open in a soundless moan as Sheldon pressed down. Leonard gasped as Penny kissed the spot under his ear and said something to Sheldon. He couldn't hear anything; the blood rushing through his ears was too loud. He did watch as Sheldon unhooked her bra, revealing perfection, her underwear following the bra to where ever Sheldon had banished it. Penny slipped hands under Sheldon's shirt and pulled it off of him before pressing against him tightly and kissing him again. Watching them brought him back up for the second time and when they pulled apart again, she turned to look at him.

"Are you alright sweetie?"

He nodded mutely, before sitting up and touching her hip, tracing slightly prominent hip bones. She sighed, her head resting against Sheldon's shoulder as she reached for Leonard's face and smiled, "If someone doesn't do me right now, I'm walkin' out of here."

Leonard smiled and choked out a laugh, before grabbing at her wrist and pulling her down to him before he rolled them over, "That can be arranged."

He looked over his shoulder and grabbed at the condom Sheldon was handing him. He inhaled sharply as a slick and cold press of a finger slid inside his body and he hissed into Penny's shoulder. Penny cooed gently into his ear, fingers combing out the knots she'd put there while Leonard shakily reached down and slipped the condom on. Sheldon added a second finger, stretching the muscles that Leonard had grown unaccustomed to using for this activity.

"I'm not going to break Sheldon, we've done this before."

Leonard got annoyed, his face still buried in the spot where Penny's neck met her collarbone. His lips tickled her and she wriggled around only to be stopped by a downward press of hips.

"We haven't done this in a while, Leonard; I don't want to hurt something."

Penny laughed, of course, only Sheldon could make the condition of Leonard's ass sound so not-sexy while still relating it to what they were about to do. Leonard looked up from his new favorite spot and glared at her. He bit into her neck and she arched up, feeling him fill her instantly as he thrust his hips in a forward motion. Her fingers raked down his back, leaving white marks in their wake before they disappeared completely. They began pushing into each other, enjoying the connection before Leonard slowed.

"Don't, don't stop." Penny whispered into his ear before looking up at Sheldon, "Oh, yeah, yeah okay. What do you need me to do?"

"Stop squirming, you distract him." Sheldon applied an ample amount of lube before pressing against Leonard entrance.

Penny stayed still and she felt Leonard gasp against her and pull out slightly, pushing his ass into Sheldon's groin. She wouldn't be able to lie later and say that the sight of the two moving as one didn't send a shot of heat straight to her groin, causing her to clench tightly around Leonard. Leonard couldn't help whining slightly; apparently it was a little more than he anticipated.

"Oh," Leonard only had to say breathe it once before Sheldon pulled back and then pushed in again. Penny felt Leonard push in when the other pulled and they began rocking against each other. Sheldon set a steady rhythm, one to keep Penny satisfied and one that didn't rush Leonard. They stayed like that for a while; before Penny moved her leg, avoiding a cramp and her body felt the flood of raw pleasure as her legs opened wider.

Penny pulled Leonard down for a kiss but he bypassed her mouth and went straight for a pert nipple. She inhaled, chest heaving as she threw her head back and moaned loudly. He bit the soft skin as he felt her muscles tighten their grip on him even more. A laugh erupted from his kissed red lips as he went back to her mouth and nibbled on her jaw softly.

"Done already?"

She smiled tiredly and reached around to squeeze his butt, Sheldon's hips bumping against her hands with every thrust. Thin hips jerked in response to the sudden grope and Penny felt them moving against her, Leonard's face returning to her collarbone as he puffed a little bit as he continued to push inside of her. Sheldon continued, not caring or not noticing that Penny had finished before them. Penny felt them reaching the end when they began moving faster against each other, rocking into her a little harder, but when Leonard surged forward, thrusting harder than he had before, she knew they were done. Leonard made a high pitched keening noise into the skin of her throat and Sheldon remained silent, jaw slack.

They collapsed on the bed, Sheldon quickly moved to the side and Leonard pulled himself so that he was resting on his elbows above Penny before rolling to the side and pulling her on top of his body. The blond snuggled into his chest and promptly fell asleep while Sheldon retrieved his shirt, pants and boxers and exited the room. Leonard smirked before following the woman's example.

Step 5: Analyze Your Data and Draw a Conclusion

Leonard came home one night, late and found Penny asleep on the couch, her toes tucked under Sheldon's thigh as he watched a tivo-ed episode of Doctor Who that he'd missed Saturday morning in favor of shower sex. Penny woke up when the warmth on her toes was no longer present and she found the two already going at it without her. She smiled and decided to watch just this once.

Step 6: Communicate Your Results

Penny called her cousin with a satisfied smirk on her face.

It's been forever since I actually posted something....

This is cross-posted on my LJ which also has a Commentary link, so if you want to know why I wrote something a certain way, just go there. The link is in my profile.