Sheldon looked up from his mail as Penny entered the building. He tilted his head to study her as she approached. "You are upset?" he asked calmly.

Penny sighed as she opened her mailbox. "How'd ya guess?"

Sheldon smiled, proud of himself. "I am getting better at reading you. I must say, it is not always easy, Penny. Your emotions are often erratic."

She rolled her eyes and headed toward the staircase. Sheldon fell into step beside her as they ascended. "I got a job performing Baby, It's Cold Outside at the Community Center with a theater group. I just found out today that the guy I'm supposed to be singing with has been hospitalized with double pneumonia."

Sheldon frowned as they turned the corner to the second floor. "Maybe he heard you sing and decided to bow out."

Penny glared at him for a second before her shoulders slumped again. "I've been taking lessons, Sheldon. Besides, we weren't exactly singing it. The song is more like a conversation set to music."

He nodded as they headed up the next flight of stairs. "I am familiar with the song. My mom objects to it's use as a Christmas song."

"Why?" the blonde asked curiously.

He shrugged and stopped to look at her. "There are several lines where the woman is saying "no" or that she has to leave, but the man refuses to listen. He plies her with alcohol and seduces her. My mom thinks it is inappropriate to sing it during her savior's birthday."

Penny shoved her hands in her pockets. "Well, without a partner, I won't be."

They began moving again, silently. Sheldon thought about what Penny had said. In three years they had known one another, Penny had performed many favors for him. In all honesty, he relied on her more than anyone else. Especially since The Betrayal.

Penny had shocked him when he found out what his former friends, now acquaintances had done. If he was a betting man, he would have bet she would have entered into a carnal relationship with Leonard when the group returned from the Arctic. Instead, she had driven to Galveston, alone, to bring him back home.

She rarely spoke to the others, which infuriated Leonard. She would not come over if the others were around. He knew Leonard blamed him for it, although he never said so out loud. Penny would not stand for that.

No, Penny would defend and help him to the best of her ability. She always had. Mind made up, Sheldon stopped on the step below the fourth floor landing. Penny, who had taken that last step up turned to face him.

"I will do it," he said calmly. Penny looked confused so he rolled his eyes. "I will be your partner in the performance."

Penny's jaw dropped and she stared at him for a moment. "Sweetie, you don't sing."

He snorted. "Neither do you. However," he hurried on when her eyes narrowed, "I am certain that with a little practice, you and I can perform admirably together."

Penny's first reaction was to giggle. She refrained, though, because she knew he was being sweet. Her second reaction was to urn him down nicely. Then she actually looked into his eyes. He wasn't just being sweet. He was being, in his own Sheldon-y way, sincerely helpful.

And Sheldon was a genius. Wasn't he always telling her that when you understand physics, you can do anything? So what were her options? Pass on the spot or take Sheldon up on his offer. It was an easy decision to make.

"Okay. How about I order pizza around 7 and we can practice a bit then?" she asked.

Sheldon nodded as he stepped up onto the landing and headed to his own apartment. "I will see you then."

When Leonard heard Penny talking on her phone to a friend about her song at the showcase, he figured that if he could get her alone maybe he could talk her around to forgiving him. After all, it was just a prank! So, he bought a ticket and sat near the back. He suffered through a horrible rendition of The Christmas Shoes, two men who mimed… something holiday-ish, and then the lights dimmed. He sat forward eagerly, knowing Penny was up next.

"I really can't stay."

Leonard's jaw dropped as his roommate stepped into view.

"Baby, it's cold outside."

His hands clenched as Penny moved into view from behind Sheldon, one hand sliding over his shoulder.

"I've got to go away." Sheldon smiled shyly down at Penny.

"Baby, it's cold outside." Penny stepped in front of Sheldon and grinned slyly.

"The evening has been…" Sheldon leaned slightly into her.

"Been hoping that you'd drop in." Penny walked her fingers down the lapel of Sheldon's suit.

"So very nice," Sheldon sang softly.

"I'll hold your hands, they're just like ice," Penny cooed as she threaded their fingers together.

Leonard scrambled out of his chair and through the exit. His head spun and his stomach threatened to embarrass him. Sheldon and Penny. He knew they had stayed friends. He never even suspected that there was more to it. Why would he? Sheldon was a robot!

Except, now he had seen them on stage. Practically making love to one another with that stupid song!

Leonard froze. Oh, hell! He lived with Sheldon! He was going to have to watch their relationship develop! No! That was like seven different kinds of hell!

Penny opened her door as soon as Sheldon finished his knocks. "Hey sweetie. What's up?"

Sheldon stepped into her apartment and handed her a piece of paper. "Leonard has given me notice that he intends to move out, Penny. He packed a bag and is staying with Raj until he finds a new apartment."

Penny read the note with surprise. "Did he say why?"

Sheldon shook his head. "No."

"Oh, sweetie!" Penny said softly. "Are you okay?"

Sheldon considered the question for a moment. "Yes. I believe I am. Although, this does present me with a dilemma."

Penny went to make a kettle of tea. "What's that?"

"I am now in need of a new roommate." He looked at her in an appraising manner. "Penny, are you still having trouble meeting the demands of rent, utilities and food while you pursue your highly unlikely dream of stardom?"

Her eyes narrowed for a moment before she brushed off the last part of his question. "Yeah, sometimes. Why?"

"You could room with me. It would solve both our problems."

"Whuu… what?" she asked, certain she had misheard.

"You need financial help, and I need someone I can trust, who understands my schedule and I can tolerate," Sheldon said calmly. "Would you be willing to move across the hall?"

Penny was silent for a moment. "Can I think about it?"

Sheldon nodded as he sat down to await his tea. "Of course."

Leonard sat down at the cafeteria table and Howard grinned at him widely. "Looks like your suspicions were right."

Leonard paled, knowing immediately what Howard was talking about. "Oh?"

Howard nodded. "Word around campus is that Kennedy, that cute little blonde physics grad, went to Sheldon's with a chocolate cake. Sheldon's new roommate, a vivacious blonde in a waitressing uniform, scared her off by threatening to hogtie her and leave her in the middle of a field."

Leonard slumped in his chair and sighed. So, Sheldon and Penny had moved in together. The song was right. It really was cold when you're on the outside.

A/N: I adore Joseph Gordon-Levitt, and after watching him and Lady Ga-Ga sing this song together, I just had to place my beloved Shenny in a situation where they would sing together.