Sheldon was ecstatic! He hadn't been this dizzy with joy since they got fibre optic broadband in the apartment. Granted, his first day as a Professor had been an unmitigated disaster, and he'd most certainly caught a severe bacterial infection from that turtle-necked traitor, Howard. But this! This was more than compensation for his damaged immunity.

"Pharmaceutical rep you say?" he cooed to the sophisticated blonde, wearing an uncharacteristic grin which made Leonard uneasy.

"Yes, it's official. I just had my first day!" Penny said, happily clapping her hands together in excitement. She cut a fine figure in that dark suit, with her closely cropped hair and all too expensive but devastating heels.

"And you visit doctors?" he asked, fully knowing her answer.

"Yes, looooads of them, every day of the week! But we call them… physicians, Sheldon," she mocked.

"Of course." He said, sweetly.

Leonard's frown grew deeper. There was something in Sheldon's behaviour which troubled him more than the fact he was angling for free drug samples.

"Tea?" Sheldon offered.

"No thank you Sheldon, I have all these drug names to memorise before tomorrow. I have to go home and practice," she said, rising to her feet and making her way to the door.

"Do you want me to come over and help?" Leonard interjected with a grin.

"Not tonight sweetie, I don't need distractions," she winked.

"Penny?" Sheldon chimed.

"Yes?"

"You know… I'm getting used to your hair now… I think…and yes, I think I like it."

Leonard rolled his eyes and gathered up the cups.

"Thanks Sheldon." she said, and was gone.

Familiar sounds floated out from the television as the bespectacled man returned to his seat, but he could feel a set of piercing blue eyes fixed on him.

"Leonard?" came a tentative plead.

"Yes?" he answered with mild irritation.

"I have a proposition for you."

Leonard turned and looked over the top of his glasses, fully expecting he wouldn't like what he was about to hear. "What kind of proposition?"

"Well… and I'd like you to consider all the angles before you make a decision," Sheldon warned. "Don't just say 'No' immediately."

"Okaaayy."

"Well, given recent events, and err, more accurately occupational shifts, I was wondering… if you would consider transposing our girlfriends," said Sheldon. There was no answer from the other man, who simply stared back as if he were frozen in time. "Leonard? Did you hear me?"

"I heard you!" Leonard snapped.

Sheldon's big pupils darted back and forward as he waited for an answer. "…annnd?" he prompted.

"NO!"

The tall man frowned. "I don't think you considered that at all," he replied sulkily.

"Fine! What the hell do you mean by… transposing?"

Sheldon shrugged, "Surely it's self explanatory. It means you have Amy as your girlfriend and I have Penny."

"NO!" repeated Leonard more sharply, leaping out of his armchair and striding to the fridge.

"You're being very unreasonable." Sheldon called after him.

"I'm being unreasonable?" he shot back.

"Yes! Penny's new occupation increases her suitability as a girlfriend quite substantially. And you, of course, can have Amy."

"I don't want Amy!"

"Why not? She's very punctual."

"Oh for crying out loud Sheldon. They're not comic books, you can't just swap them. And I love Penny, we're engaged!" he bellowed.

"Yes, you are right, they would have to be consulted, and I imagine Amy would be most aggrieved to get up one morning as Dr. Sheldon Cooper's girlfriend and the next to find she was yours."

Leonard's mouth dropped open. He couldn't think of a single thing to say in response. Grabbing a bottle of beer from the fridge, he decided to ignore the rest of this conversation but Sheldon was far from finished.

"Daily access to dozens of physicians and new drug samples… " he muttered.

Leonard continued to stare at the television and ignore his crazy roommate.

"…I could ask her to take in my cultures for a third, fourth, fifth opinion." He continued dreamily.

"She wouldn't do that!"

"Oh, I'd put it in our relationship agreement."

"Your what?!" Leonard snapped, "I'm going to bed." He huffed and stomped off to his room.

"What about my proposal?" Sheldon called out, but there was no answer. "Damn it!" he sighed. "I should have put a girlfriend transposition clause in the roommate agreement."