So, Penny and Howard are childhood friends. She's moved back to Pasadena suddenly and is staying with the Wolowitz family. Leonard and Raj are immediately infatuated, but somehow Sheldon is the one on an outing with her.

Sheldon stared at the dashboard nervously. "Do you realize your speedometer is not working?" he asked with a bit of alarm.

Penny nodded, one hand on the wheel and the other resting on the gear shift. "Yep. It sticks sometimes. Don't worry. With this traffic, we can't go more than 20 anyway. So, which way to the train store?"

Sheldon glanced at the street signs briefly. "Take a right three blocks up."

"So, what's your name again, Sugar?"

"It is Dr. Sheldon Lee Cooper," he said primly. "You may call me Dr. Cooper."

She laughed lightly. "That's a little too stuffy. How about Shelly?"

He glared at her fiercely. "My mother calls me that. I hate it."

Penny glanced at him as she stopped at a red light. "Well, I'm not calling you 'Dr.' anything. If you and I are going to be friends, you're going to have to lighten up."

Sheldon looked at her curiously. "What make you think we will be friends?"

Penny laughed. "You're a bit tightly wound, aren't you? That just makes me want to pull the car over and muss your hair or something. Anything to make you loosen up a bit."

Sheldon sniffed disdainfully at her. "I do not need loosening up. I am perfectly happy as I am. Take a left onto the next street. The store is halfway up the block on the right."

Penny parked in the first available spot she found and turned to look at Sheldon. "Are you sure you and Howie are friends?"

"He is a treasured acquaintance, not a friend," Sheldon sniffed.

Penny burst out laughing and opened her door. By the time Sheldon had joined her on the sidewalk, she was wiping moisture from her eyes. "Sugar, you are absolutely adorable. I'm really going to enjoy getting to know you."

Sheldon watched her head toward the store entrance with confusion. She was irrational, possibly unstable, and incredibly irritating. She was also fascinating. Somehow he suspected that his well ordered life was about to be knocked off-kilter.

Howard placed the tray of cookies and Sunny D on his desk while Raj shut his bedroom door. He glanced over at Leonard and frowned. "Hey! Put that stuff down!"

Leonard looked up guiltily from the bottle of perfume he was holding. "I was just reading the..uh, label."

Howard rolled his eyes. "Yeah? Well, I happen to know you had to dig it out of Penny's bag to find it, so put it back. She hates having her stuff touched.

"Who is she?" Raj asked eagerly. "She's like a goddess," he said dreamily.

Howard snorted. "Wait until you get to know her. She's more like a bull in a china shop." He grabbed a glass of juice and sat down at this desk facing them. "Penny is my oldest friend. We've known each other since we were in diapers. Her mom and my Ma were best friends until Aunt Emily passed away a few years ago from kidney failure."

"How is it we've never met her before?" Leonard asked suspiciously. "You've never even mentioned her."

Howard shrugged. "She moved out to New York when she got married. We still call, email, and chat online, but I have only visited her twice since she left. I never mentioned her, because there was no reason to."

"So she's married?" Leonard said glumly. "Of course she is. A beautiful woman like that, she's probably married to some movie star."

"More like a cheating ass," Howard muttered angrily. "Kurt is a piece of crap. But he swept her off her feet when she was vulnerable, and immediately moved her away from here. She divorced him, finally."

Leonard perked up. "Really?"

Howard groaned, regretting his runaway mouth. "Yes, so leave her alone. She's not looking to date anyone. The last thing she needs is someone fawning all over her, Leonard."

Leonard looked at Howard innocently. "Of course!"

Raj looked from Howard to Leonard and back. He could already tell this was not going to go well.

Sheldon was reaching for a 4-4-0 locomotive with a water car when Penny stunned him by slipping between him and the shelf and plopping a conductor's hat on his head. He was so surprised, he completely forgot that he hated having someone so close to him. "What are you doing?" he asked sternly.

She grinned cheekily. "I knew it! That looks so cute on you!" She held up two separate train sets. One was the Santa Fe Flyer and the other was the Liberty Bell Special. "Okay, Chris is going to be eight. Which one do you think I should get him?"

Sheldon looked carefully at each set. "I believe that the Liberty Bell is the better train. It has E-Z Track, which means the rails snap together very easily and hold in place better. Also, the cars themselves are made of a studier material than the Santa Fe, which means an 8 year old can handle it a bit rougher without worry of breakage."

Penny grinned and nodded. She snatched the hat back off his head and headed for the counter. "Thanks, Sugar!"

Sheldon watched the exuberant blonde bounce away with mixed emotions. Confusion, nervousness, irritation, and (surprisingly) a desire to impress warred within him. She was beautiful, but he knew many beautiful women. She was friendly, but he knew many friendly women. So why was he curious about her? And why did she still seem so familiar?

"I can't believe you just took off with Penny like that," Leonard said as they headed up the stairwell of their building.

Sheldon rolled his eyes as Leonard continued to grumble. "She took me to the train store. Unlike you and Raj, who promised me a trip to the train store, but instead tricked me into going to the Wolowitz residency in pursuit of carnality."

Leonard glared at Sheldon. "Look, just because you are a robot, doesn't mean the rest of us are. I've got to make Penny notice me before she meets some moron with more muscles than brain cells! You monopolizing her time isn't helping my cause!"

Sheldon frowned as they reached the fourth floor. "What if Penny has no interest in you?"

"She just has to give me a chance," Leonard said confidently. "We're destined for each other. I can feel it."

Sheldon unlocked the door to his apartment and turned to watch Leonard unlock the door to his. "Sometimes I wonder if you are losing your grasp on reality." He reached out, opened his door and sighed.

Leonard looked at the empty apartment with amusement. "Looks like your roommate moved out. Again."

Sheldon stepped inside and looked at the mostly empty living room. All that remained was his desk, a table lamp on the floor and his bookshelves filled with graphic novels and DVDs. Across a white board, in the center of the room, was the message "DIE HELLSPAWN, DIE!"

"I suppose I'll have to advertise for a new roommate," he mused as he hung his messenger bag across the back of his desk chair. "I really must get to work devising a questionnaire for potential roommates."

Leonard snorted and headed across the hall to his own apartment. In the 2 years he had lived in the building, he had seen 11 guys move in and almost immediately move back out. No one could put up with Sheldon's brand of crazy for long. Once again, he was grateful he lived across the hall and not in 4A. He'd have killed the crazy physicist after the first week.