There was a nervous energy buzzing in the air, fluttering between the two of them, but that was to be expected. This was, after all, their first time. Figuratively speaking, but nevertheless.

The rules of the experiment were firm, but reasonable, and after discussing them at length and reaching a verbal agreement, Sheldon had proposed to conduct the experiment in his bedroom, as he'd explained that it would not only give them the necessary privacy, but decrease the likely possibility of being interrupted should Leonard return home. Amy had easily agreed to this, praising him for his sensibility, and now, they both sat on Sheldon's bed, facing one another, sitting closely, though not close enough that there were any body parts touching.

At least, not yet.

They were both waiting for each other to make the first move. Their eyes were locked, as though they were having an intense staring contest, and Amy's skin tickled with anticipation. This entire scenario screamed familiarity, as she was reminded of the last time they'd sat like this, over a year ago, when they engaged in metaphorical sex in the realm of Dungeons and Dragons. That experience had been a small, glimmering look into the world of physical intimacy Amy so desperately craved, and when she thought about how far they'd come in their relationship since then, it made her head spin, in a good way.

"Are you ever going to start?" Amy asked, unable to wait any longer.

"I don't see why I have to be the one to initiate," Sheldon said in a petulant tone.

There were times when Amy found his childlike behavior endearing, as he could be so unbelievably naïve and clueless on so many things despite being an absolute genius when it came to most everything else. However, in this moment, she did not find his behavior even remotely endearing. In fact, right now, she found his stubborn attitude nothing short of infuriating, and she expressed her frustration with a loud sigh and a deliberate rolling of her eyes.

"Fine," she said, "I'll start."

She lifted her hand, only to freeze, suddenly feeling shy and hesitant. This was really about to happen. They were really going to do this. Sheldon sat perfectly still, which only made her feel even more nervous, because she knew he was waiting for her to touch him. He was ready.

With a jolt of determination striking her, Amy reached out to him. His eyes followed her hand as she settled on her target by gingerly touching his chest. Her fingers carefully spread across his left pectoral, directly above his heart. She let out a quivering breath that she hadn't realized she'd been holding in, and she took a moment to simply admire his chest, lean, yet solid. Remarkable.

She looked up into his eyes, and there she held her gaze, expecting him to recoil. They stared at one another for a beat, and then another, and another. It was intense and overwhelming, making Amy feel warm, too warm, and, as a result, she found herself unable to speak, and she had to look away.

Come on, Fowler. He's waiting.

And yet, nothing.

"I kiss you," Sheldon said out of nowhere.

Amy's eyes jumped back up to meet his eyes, the fear instantaneously draining from her system. He had a serious look on his face, while she felt a sly smirk tick up at one corner of her mouth. He really was ready.

And now, so was she.

"Where?" she asked daringly.

Sheldon's confidence wavered, his eyes bulging.

"Where?" he repeated in surprise.

Amy bit her lip, taming the mischievous little smirk of hers, while Sheldon's Adam's apple bobbed as he swallowed, his gaze shifting from her face as he pondered for a moment, until he looked at her straight on again and gave her a matching devious smirk of his own.

"Your neck."

"Oh," Amy said, a thrilling shiver racing down her spine, her smile widening. "Okay. Continue."

"Very well," Sheldon said, "but, as per the rules, you'll need to let go, since it's now my turn."

She did, allowing her hand to fall away and come down to rest in her lap. Sheldon leaned in closer to her, and she felt a fire ignite, sweeping through her body.

Yes. Touch me, Sheldon.

His hand settled on top of her knee, and Amy found herself wishing more than anything that she wasn't wearing tights, so that she could feel his warm hand directly on her skin. Still, she closed her eyes, shuddering from the contact, a sweet sigh leaving her lips.

"I graze my mouth along your neck, sucking gently," Sheldon said.

Amy moaned her approval, her smile stretching farther to one side of her face. "That feels amazing," she said, basking in the warm, powerful glow of her fantasies. Her skin tickled, heating up, as though she truly could feel the warmth of his mouth on her neck. "What about your hands?"

"My hands…reach out to lovingly caress your…breasts," Sheldon said. "I squeeze them softly while kneading them in my palms."

"Oh, my," Amy said, beginning to lose sight of herself, melting into Sheldon's imaginary touch, while, in reality, he gave her knee a small squeeze. This experiment was turning out to be so much better than she imagined. She needed more. "I…" Her eyes popped open. "I believe it's my turn now," she said with an eager grin sprawling across her face.

Obligingly, Sheldon released her knee and settled both of his hands in his lap. Amy took a moment to freely rake her eyes over his body in a full sweeping motion. She noticed the way Sheldon squirmed slightly, clearly affected by her gaze, and she smirked in a way that was both intimidating yet promising. Finally, she brought up her hand and, once again, rested her palm over his chest.

"As I roam my hands down your…magnificent chest," Amy said, pausing a moment, becoming distracted. Her hand flexed against his chest, fingers clenching, the heel of her palm nudging against his racing heart. "I kiss you deeply…on the lips."

A low grunt escaped Sheldon's lips, a noise so arousing that Amy found herself wanting to go even further, and so, she began sliding her hand down his chest, grazing across his abdomen, running lower, and lower, and—

"No bathing suit areas," Sheldon said in a stern, albeit noticeably shaky voice.

"I'm never one to break the rules, Dr. Cooper," Amy said, her eyes glinting with mirth as she settled her hand just above his belt. She let her words do the rest. "I dip my hand below your waist and firmly grasp your—manhood."

"Oh, dear Lord," Sheldon said, the closest he'd ever come to uttering passion-induced profanity. His body writhed beneath Amy's touch.

She smirked. "I give you a slow, tantalizing stroke, feeling you grow in my palm."

Sheldon made another noise, a trembling whimper. His eyes were closed, and his tongue darted out as he swallowed.

Amy's heart pounded.

"Oh-kay," he said, voice cracking. He cleared his throat and opened his eyes. "Yes. Um. My turn."

Her hand slipped off his body, while he brought his hand up, and this time, he gently touched her cheek. It was the first skin-to-skin contact of the experiment, and Amy couldn't stop the quivering breath that left her mouth. She closed her eyes and listened to the sweet sound of Sheldon's voice as he stimulated her with his words.

"I…gently lie you down on the bed, and…lie myself down…on top of you."

Amy's back arched involuntarily, her head tipping up as she breathed out again. Suddenly, her eyes popped open, locking with her boyfriend's darkened gaze.

"Are you…wearing protection?" she asked.

His eyebrows briefly came together. "Protection? For metaphorical coitus?"

She said nothing, only stared, her ragged breathing the only sound in the otherwise painfully quiet room.

"Of course," Sheldon said after a beat.

Amy relaxed into another grin. "Okay," she said. "Perfect. My turn again."

His hand slid down her cheek, fingers grazing her jaw, before slipping off entirely. She grinned wider as she brought up both hands, cupping either side of his face. His pale cheeks were hot to the touch. He swallowed again, eyes drifting closed.

"I…" She swallowed heavily. "…wrap my arms around your shoulders and…kiss you harder than I've ever kissed you before."

Now, Sheldon brought up both of his hands, grasping Amy's shoulders.

"I…kiss you back full force, and then I…pull away and…look adoringly into your beautiful eyes as I…enter you," Sheldon said.

I can't breathe, Amy thought, her heart pounding so hard she felt her pulse throbbing throughout her whole body. The experiment was taking on a life of its own. She let her hands slide down his face, over his neck, back to his chest, fingers curving against the soft material of his t-shirt. Sheldon didn't let go of her, but instead, gripped her shoulders harder. They were no longer abiding by the rules, but now was certainly not the time to tell him to let go.

"I…arch against your body and moan loudly," Amy said.

"And I…" Sheldon paused. His voice sounded deep and grainy. "…begin thrusting inside you, slowly and deeply."

Yes. Don't stop.

"I meet your thrusts and throw my hands over your back, pressing our heated bodies together to create a sensual friction," Amy said.

"I…increase my speed as I lean down and kiss you so passionately it takes your breath away," Sheldon said, his hands sliding down her arms.

Oh, yes, she thought as another shiver rippled through her body.

"I writhe against you," she said, "only to break the kiss as my body mounts with pleasure."

"I whisper in your ear to climax for me, Amy."

"I do," Amy whispered, body quivering.

"And I climax as well, experiencing the greatest pleasure I've ever felt in my life," Sheldon said.

"And, after it's over, I wrap my arms around you, enjoying the sound of our breaths mingling as I give you a soft kiss on the lips," Amy said.

They both fell silent. Amy's hands slipped off of Sheldon's body, one lying flat on top of his comforter, the other balled up in her lap. Sheldon's hands slipped away as well, and, when Amy felt his hand touch hers, she gasped softly, her eyes flying open.

She dropped her gaze to stare down at Sheldon's hand, resting comfortably on top of hers, and this physical contact alone, something so simple and innocent, was so much more intimate to her than anything they'd said to each other throughout this entire experiment of theirs. She didn't dare move her hand, or even comment on the fact, in fear that by drawing attention to it, he would break and move his hand away.

"Was that…satisfying for you?" Sheldon asked, and there was something new in his voice that she'd never heard before, something deep, gravelly. Husky.

"Immensely satisfying," Amy whispered. "Was it…satisfying for you?"

There was a pause. She looked up at him again. His eyes shined with longing as he answered her, not verbally, but with a small nod of his head. He inched his head towards her, his eyes falling shut again. Amy closed her eyes as well, and she held her breath as she felt the delicate pressure of Sheldon's soft lips touching her own. She relaxed into it, a sigh escaping her mouth as Sheldon's lips grazed hers for only a few moments, before pulling away.

Amy didn't move. Sheldon didn't move. She opened her eyes, taking in the mesmerizing, fiery look in his eyes. He leaned in again, and this time, when their lips connected, it was deeper, harder. Amy tilted her head up to better meet his lips, and then, she felt something completely different that had her heartbeat fluttering wildly.

Sheldon parted his lips, the warmth of his mouth flooding through her, making her weaker, and she responded by opening her mouth as well. She felt his tongue as it licked her bottom lip, slowly, tickling her a little, before it slipped inside. When his tongue met hers for the first time, Amy instantly let out a moan that she simply could not control. It was low, but Sheldon seemed to respond well to it, as she felt his hands, warm and strong, come up to grasp her face.

Out of reflex, Amy brought up her own hands and tightly gripped his shoulders. Her thoughts spiraled as the fire in her body grew larger, powerful tingles shooting up and down her limbs, her heart pounding in excitement. It was a strange sensation, with their wet tongues tangling together, moving back and forth inside Amy's mouth, but the heat between them only skyrocketed, and she was loving every second of it.

Sheldon abruptly broke the kiss, breathing out really hard, and Amy crashed to reality. She let go of him, while his hands slipped from her face, and as she panted, she could only stare at him, noting how his swollen lips were slick with saliva. Is that his saliva, or mine? She unconsciously drew her own lips together, bringing up a hand and running it through her hair, before she rose from her spot on the bed.

"I should probably head home now," she said. "Will you walk me out?"

"Yes," Sheldon said. "Of course. I just…I'm going to need a moment."

She stared at him, taking in the way his chest rose and sank as he sharply breathed in and out. She also took in his reddened ears, the look of obvious discomfort on his face, the way he was purposely avoiding her eyes, and finally, the way his hands drew to his body, strategically cupping the growing bulge in his pants. She didn't want to embarrass him, but at the same time, she knew she needed to help him out.

"Think of Howard's mother wearing nothing but an ill-fitting, two-piece bathing suit," Amy said.

Sheldon froze. His chest fully sank with a slow, relaxing breath, and he looked down for a moment, before finally looking up at her.

"Wow," he said, standing up at last. "That worked like a charm."

Amy grinned.

Leonard and Penny were sitting on the couch, watching TV, when Sheldon and Amy emerged from his bedroom. Amy walked out first, and Sheldon followed her, both walking calmly and suppressing lustful smiles. Neither one of them acknowledged Leonard or Penny, whose eyes followed them as they made their way across the room.

When they reached the door, Sheldon and Amy turned to each other, and now, they were both grinning widely, their faces bright with plain and utter happiness.

"Goodnight," Amy said.

"Goodnight," Sheldon said.

Their eyes lingered on each other as Leonard and Penny watched them. Suddenly, Sheldon turned his head to glance at the two of them, an irritable look crossing his face, and Penny snapped her eyes away, pretending to stare at the TV, leaving Leonard to do the same.

As soon as Sheldon turned back to Amy, however, Penny looked at them again, needing to catch every second. Sheldon leaned down, giving Amy a kiss on the lips, and Penny's mouth fell open.

"What is happening?" she whispered to Leonard, who seemed far less interested in watching Sheldon and Amy lock lips.

When they broke away, Amy's eyes were shining even brighter than before. She left, but even after the door closed behind her, Sheldon stood there in a daze, while Leonard finally spoke up.

"Hey, Sheldon, what were you and Amy doing in your roo—"

A twisting grip on his arm had Leonard's question morphing into a pained wail.

"Ow," he said as Penny squeezed his arm with unbearable strength. "What the hell?"

He turned to his fiancée, but she wasn't paying attention to him. Her eyes were on Sheldon, who finally turned from the door and made his way back across the room, his hands slipping behind his back and that small, secretive smile still on his face.

"Shh," Penny said. "He's having a moment."

It wasn't until Sheldon reached the kitchen that he stopped, and the smile dropped from his face. He looked from the counter, to Leonard and Penny.

"Which one of you left the milk out?" he asked.

Penny's grip tightened. "Okay, the moment's over, the moment's over," she said in a rushed breath, giving Leonard a pleading look.

He sat up, letting out a sigh. "Uhhh. I did. I made Penny coffee and forgot to put the milk back in the fridge."

Sheldon narrowed his eyes, a perturbed look on his face, an expression he held as he picked up the carton of milk and opened the refrigerator.

"In that case, on behalf of Penny…" He paused, and, after placing the carton inside and swinging the refrigerator door shut, he pointed to Leonard and said, "You've just lost sex tonight."

"What?" Leonard said. "You can't do that. He can't do that. Right?"

He looked at Penny, who was now smiling in absolute amusement, and she merely gave him a shrug.

"Now, if you'll excuse me, I'm going to go take a shower," Sheldon said, which only deepened Leonard's confusion.

"Wait, what? Two showers in one day? What gives, Sheldon?" Leonard asked. "Was that abnormally long shower you took this morning not enough for you?"

"Evidently, no, it wasn't, but I've said too much already, Leonard," Sheldon said, heading down the hallway.

They heard a door close and the water turn on, and Leonard and Penny shared an apprehensive look.

"Should we—"

"Yes," Leonard said, and they got up and headed to Penny's apartment without another word.

Author's Note: Thanks for reading! I hope you enjoyed the additional chapters. I certainly enjoyed writing them. Please share your thoughts in a review. :)