Starting from the beginning, how different would TBBT have been if Penny was a single mom when she moved into apartment 4B? Let's find out.

Sheldon hung up his coat and messenger bag on the back of his chair. He turned to see his roommate staring at the door. Uh, oh. Sheldon knew that look. Leonard was interested in their new neighbor. Normally that would not be of any interest to him, but he had experienced a distinct and unsettling reaction to the pretty blonde moving into 4B. He was certain that he should avoid her if he wanted to maintain his comfortable, hassle-free lifestyle.

"I'm going to invite her over for dinner. It's the neighborly thing to do," Leonard said with a dreamy smile.

Before Sheldon could formulate an adequate excuse, Leonard was out the door. He followed with resignation. This was not a good idea. Leonard knocked on the door and it opened. He opened his mouth but paused. With a bit of confusion both men looked down. Wide green eyes under a mass of light brown curls looked back at them.

The child was holding a stuffed Scooby Doo doll by the tail. She stopped sucking on the third and fourth fingers of her left hand, and walked over and grabbed Sheldon's hand with her small, saliva covered fingers. Sheldon whimpered and tried to tug free, but the kid became a bit unbalanced so he hurriedly steady her with his grip. A moment later their new neighbor peered around the door.

"Oh. Hello again," she said. She reached down and picked up the little girl and settled her on her hip. "Is there something else?"

Leonard was staring at the child, so Sheldon cleared his throat. "We have Indian food. For dinner. If you want to eat with us," he said. Penny looked at Leonard with a frown and then at Sheldon. He had the impression she was trying to figure something out.

The little girl smiled at Sheldon with a gap-toothed grin. "Oki!"

Sheldon felt his cheeks grow warm at the obvious admiration on the little girl's face. Penny laughed softly, and Sheldon felt that warmth from his cheeks spread through his entire body. Dear lord! Was he coming down with something?

Penny rubbed her nose on the little girl's cheek. "No, Cat. He's our neighbor. He lives across the hall."

"Cross 'all?" she repeated.

Penny nodded. "That's right. This is Leonard and Sheldon."

"Leopard and Oki!" Cat sat happily, reaching out for Sheldon. He twitched and stared at her for a second before tentatively reaching out and patting her head. Leonard just kind of shuffled a bit and waved.

Penny smiled vaguely at the two men. "Thank you for the invitation, but I need to get Cat fed and put to bed for the night." The little girl pouted a bit but wrapped her arms around her mommy's neck. Leonard nodded quickly and moved away from the door.

"Oh, of course. Well, um. Welcome to the building. Again. Bye," Leonard said.

Sheldon nodded as Penny closed the door. He turned and followed Leonard back across the hall. Leonard sighed and took a seat on the armchair.

"Well, that's too bad," Leonard bemoaned as he pulled the food containers from the bag.

Sheldon sat down with a confused look. "What is 'too bad'?" he asked.

Leonard shrugged. "Penny's gorgeous, but she has a kid."

Sheldon frowned. "That makes her undesirable?"

Leonard nodded. "I'm not overly fond of kids. Besides, with a kid that young, it's doubtful that Penny goes out much."

"What does that have to do with anything?" Sheldon asked. "You don't go out either."

Leonard rolled his eyes. "Look, she's really attractive but having a child makes it very unlikely that she would have much time for a relationship. And what time she does have is probably spent doing kid stuff. You know, Chuck E. Cheese and waterparks."

Sheldon opened his food tray and took a bite. He considered Leonard's words as he chewed. "I do not understand. Isn't the purpose of establishing a relationship to form a pair bond and procreate?"

Leonard shook his head and sat down. "No. The purpose of dating is… well, it's not always about getting married and having kids. Sometimes it's about something else. Having a good time, getting along."

Sheldon nodded knowingly. "You want coitus."

Leonard turned a bright red. "No!" He glanced at the door and quickly looked down at the floor. "I mean, not really."

The door opened just as the guys were finishing their meal and two men rushed in. "Guess what we found!" Howard exclaimed.

"Hey, guys," Leonard said.

Raj sat down. "This is so cool!"

Howard placed his laptop on the coffee table and opened it up. "We found an early interview with Stephen Hawking!"

A knock on the door grabbed everyone's attention. Howard stood, since he was closest, and opened it up. "Well, hello," he leered.

"Hello," Penny said bit warily. "Sorry to bother you guys, but is Sheldon available?"

Sheldon flushed softly as all eyes turned to him. He stood and walked over to the door. "Yes?"

Penny looked uncomfortable. "Okay, I know this sounds strange, and I'm really sorry to bother you. It's just that my daughter won't lay down unless you come say good night to her."

Sheldon's eyes went wide. "Me? Why me?" His friends gathered around as Penny bit her bottom lip lightly.

"Cat's favorite cartoon is Hulk vs. Thor. She watches it every chance she gets. She thinks you look like her favorite character, Loki, from the movie. She thinks you are Loki. And she wants you to say good night to her." Penny looked sheepish. "Please? It would really mean a lot to her. She isn't too comfortable in the new apartment."

Sheldon ignored the stares his friends were giving him. "I have no objection," he said, stepping into the hall. He followed Penny into her apartment and through the living room. In the bedroom was a full size bed and a small toddler bed. Cat was sitting on the little bed, clutching her Scooby toy and sucking on those two fingers again.

Sheldon walked over nervously. He didn't have any experience with children, but Cat apparently knew what to do. She laid down and tucked the toy under the blanket with her. Sheldon bent over and smoothed the wrinkles out of the blanket. "Good night, Cat."

She grinned up at him. "Wuv you, Oki!"

Sheldon felt that warmth in his stomach again and he patted her head again. He stood and walked from the room. Penny turned out the light and closed the door half way.

"Thank you so much," she said softly. "I really appreciate it."

Sheldon looked down at the floor for a second before meeting her eyes. "I did not mind. How old is she?"

Penny moved to the kitchen and put on a kettle for tea. "She's two. She'll be three soon."

Sheldon followed and took a seat at the counter. "It must be difficult going through a divorce with a child so young."

Penny shook her head. "No divorce. We never married." She sighed. "Which is a good thing now, I guess. Kurt always said we would get married, but he, apparently, was too busy sleeping around to actually make that kind of commitment." She blushed and looked over at him. "Sorry. You don't want to hear my life story."

Sheldon was surprised to find he actually was interested. He cleared his throat and stood. He wasn't comfortable with the interest he had in this woman, or her child. "Well, I better be going. I have friends waiting."

Penny nodded and followed him to the door. She opened it to find his friends all standing in the doorway to 4A waiting. She looked back up at Sheldon. "Thank you, again. I really appreciate it."

Sheldon nodded and walked across the hall. He took his seat in his spot and picked up the tv remote. His friends watched him carefully.

He sighed and looked up. "Is there a problem, gentlemen?"

Leonard looked at him curiously. "What was that about? Why did you say good night to our neighbor's kid?"

"Your CUTE neighbor's kid," Howard added.

Sheldon shrugged. "It was the neighborly thing to do. The little girl is uneasy in her new home. It took little effort on my part, and made the child happy."

"So it's not that you think Penny is attractive?" Leonard asked shrewdly.

Sheldon could not keep the blush from creeping up his neck. The others looked at him with surprise. "Holy Shiva's ghost!" Raj said. "You do!"

Sheldon set his tray down and stood up. "Nonsense," he said as he hurried back to his room.

Once he was gone Leonard looked at Howard and Raj. "Wow! Sheldon has a deal after all." Leonard grinned. "This will be interesting to watch."

Raj shook his head. "You know he's clueless about people, and probably more so about women."

Howard nodded. "We'll have to help. No way will he land your cute neighbor on his own."

Leonard nodded and the three men began watching tv.