Originally written on 9/5/2009 and posted at Paradox, the Sheldon/Penny LiveJournal Community.

"Sheldon, honey, it's not very hard," Penny coaxed, deriving some small amusement out of the way his face tightened in frustration. She knew he was thisclose to start twitching. "Don't think, just ans—"

"Don't think? Penny, telling this mind not to think is like telling the area of a circle divided by its radius squared to not equal pi."

"No it isn't," she dismissed, and before his affronted look could turn into an affronted ramble, she said, "Look, I'll give you an easy one. Tea or coffee?"

He spared her with a long-suffering, withering look before stating, "Tea."

"You're doing it wrong!"

Cue eye twitch.

"You have to be quicker than that. Like—Leonard, help me. Give me something to answer."

Leonard, Raj, and Howard were watching them, clearly enjoying watching Penny tell Sheldon that he wasn't doing something properly.

"Hm," Leonard said, thinking a moment. "Screwdriver or sunrise?"

Penny's answer came almost before he finished speaking. "Screwdriver." She paused. "Huh. I always considered myself a tequila gal," she mused, looking surprised at herself. Then she snapped out of it. "See? Like that. Okay, Sheldon—"

"I fail to see the objective of this silly game." He began to raise himself out of his spot But she caught him by the shoulders and shoved him back onto the couch, causing him to spasm and shrink away from her, into the arm of the sofa.

"No, stay! This is psychology. And it's fun. See? You learn things about yourself."

"Penny, Penny, Penny." His voice was condescending. "I know everything there is to know about, as I have told you before, the important things in this universe, and I happen to be high on that list. Now, if you'll excuse—"

"Shut up, shut up." Penny flapped her hand in front of him. "Now, Batman or Superman?"

He watched her, eyes narrowed. Then he said, "Batman."

"Faster. Seashells or sea glass?"

"...Seashells."

"No pausing! Markers or crayons?"

"Markers."

"Bosonic or heteronic?" This one came from Howard.

"Heteronic."

"Kirk or Solo?" Raj through Leonard.

"Solo," he responded, and jumped a little, head snapping to the side as if he had shocked himself.
Penny smirked. "See?"

He apparently heard 'C' because he exclaimed, "Carbon!"

He was sitting up straighter, his hands clasped over his knees, very into this game for someone who had scoffed at it minutes earlier.

"Cytosine or guanine?" Leonard drilled.

"Adenine."

"Titanium or nanotubes?" Howard asked.

"Nanotubes." Sheldon's answer had a very prevalent 'duh' in its undertones.

"Penny—?" Leonard started.

"E raised to the i times pi plus one equals zero."

All the boys stopped, including Leonard, who was offering the bowl of Chex Mix to Penny, and all of their heads, as if of one body, whipped to stare at Sheldon. Penny grabbed some Chex Mix, crunching some of the pretzels between her fingers, unaware of the sudden tension in the air. After a few moments of silence, she frowned and looked around at everyone.

"My turn? Okay, um, Firefly or—"

She stopped when Leonard, Howard, and Raj all looked at her, amazement on their faces. More than a little freaked out, she glanced uneasily at Sheldon, who was staring straight ahead. His fingers were clasped against his knees, knuckles white, and his face was paler than usual. Then he stood, his movements jerky, and strode down the hall toward his room.

The door slammed.

Everyone's eyes had followed his departure, and no one spoke in the aftermath for a few moments.

Raj, shockingly, was the one to break the silence. "Okay—what the frick just happened?"

The next day Penny heard three knocks on her door. She rushed over to it, purse on her shoulder, dressed in her Cheesecake Factory uniform and running very late to her shift.

She opened her door. Leonard was standing awkwardly on the other side, and she quelled the slight disappointment in her stomach. "Hey, Leonard, make it quick, I'm late." She stepped out of her door, turning around to lock it.

"Um, okay," he said, sounding uncomfortable. "Well, I think I need to explain to you what, exactly, happened yesterday—"

"Hm?" She began to walk toward the stairs. After a step, he moved to follow her.

"Well—e raised to the i times pi plus one equals zero is a formula."

"Okay..." Penny realized this had something to do with Sheldon's behavior yesterday. She had found it odd for a while, but odd behavior wasn't really out of Sheldon's way so she'd brushed it aside after a few hours.

There was silence.

"Leonard, sweetie, you're gonna have to do some more explaining. Telling me that it's a formula doesn't turn any wheels for me," she reminded.

"Yeah," he said, frowning at his feet as they descended the stairs. "Well—it's a pretty well-known formula in the mathematical world. It's very concise, but remarkable in that it contains the constants e and pi as well as the complex number i and—"

"Okay. Let's skip over this part."

"Okay, okay, let's pretend I explained this to you." They were nearing the bottom landing, Penny moving quickly and impatiently towards the door. "But what it means—well, it's called Euler's identity, and any mathematician that's worth anything knows the formula as, well, the most..." He struggled. Penny turned and looked at him, tapping one foot, eyebrows raised, waiting for him to finish. "...well," he started again, "the most beautiful. The most beautiful formula. And after I said your name—he, well." Leonard finally ceased speaking, looking somewhat embarrassed.

A very heavy silence followed this. Penny's cheeks flooded with color as she stared at Leonard. He shuffled his feet.

"So—" Her voice broke, just a little. "—you're saying that—"

"Yeah," said Leonard. "Um. I'll, I guess, leave you go to your shift. I guess."

She was still standing by the door, staring in the direction of the mailboxes, as he rushed back up the stairs.

Hours later, Penny was sitting on her couch, just finishing a furious battle in Age of Conan. She had gone through her shift in a daze, not making nearly as many tips as she usually did when she flirted with the unattached (and sometimes even attached) males at her tables.

There were three knocks at her door. At first she thought it was Leonard again, possibly to talk to her about what he had... revealed before she started her shift. But then she heard her name, softly spoken.

Penny waited for his third round of knocks to begin before she stood , and exactly when the man on the other side of her door uttered "Penny" for the final time she pulled the door open.

"Sheldon."

He looked normal, not any more awkward than usual, except for his eyes darted to the floor for a brief moment just before looking at her. She wouldn't have caught his embarrassment a year ago.

She shifted so she was leaning against the door-frame.

"We are in the process of replacing our WiFi provider," he said by way of greeting, "so I am informing you that the internet will be unavailable for a few hours tomorrow afternoon."

She nodded.

"So you are informed," he stated, then turned to go.

"Wait, Sheldon."

He turned around, looking at her curiously, and a bit warily.

She moved back to her apartment, and he almost walked in after her, but stopped in the doorway. Penny picked up her laptop and brought it over to him, shifting it on her arm so he could see it. She watched him bend his neck, just a little, to view her screen more easily.

"This raid. Yes or no?"

"No," he answered.

She started to move back in her apartment, and he followed, seemingly without thought.

"Tea?"

She set her laptop down as he responded, "Please."

Straightening, she turned to face him.

"Me?"

Sheldon looked at her, sharply, and Penny waited. She credited him for not ducking away.

His answer was very deliberate. "You."

A corner of her moth quirked up as she watched him watching her, and she thought, Euler's identity be damned.