The Friendship Algorithm- Takes place during and after the episode.

"Sheldon, honey, did you ever consider making friends by being... I don't know... pleasant?" She asked, only half-sarcastic.

Sheldon looked at her as if he was trying to gauge her sincerity.

"Well, that's certainly a thought-provoking hypothesis. May I suggest it for the topic of your essay?" He asked with a smirk, then turned on his heel and left her staring after him in disbelief.

Penny sighed and shut her door. She had been planning on clearing out the DVR tonight, but now she had homework.

Still, she walked into the kitchen and pulled out the vodka and diet coke. It took only a minute to mix up her cocktail, and she brought it into the living room and made herself comfortable on the couch.

Penny took a few big gulps of her drink, and sighed with pleasure as she felt the familiar warmth rush through her veins and up to her head.

She smiled, feeling the tension of the long day begin to ease.

"Okay, question two. What is Sheldon's favorite amino acid?" She snorted and moved onto the next question.

But that one was equally puzzling, and she had no idea what to answer. Penny felt the prick of tears as she began to wallow in the depression that always seemed to swallow her when one of her 'genius' friends made her feel like an idiot.

Gritting her teeth, Penny flipped over to the essay section. For few minutes, she just stared blankly at the lined page, then the thoughts came and she wrote him a letter.

Penny tried to focus on her Chinese food as Sheldon explained his intent to 'let one of his friends' go.

Leonard, of course, had an easy pass. Next Sheldon turned to Howard and listed several reasons why he should be the one let go, but he was declared as 'safe' and Sheldon turned to Raj.

Penny felt the sting of tears again and reacted angrily...

"Okay, I see where this is going. I'm not one of you guys. I'm not a scientist, so-"

"Penny, Penny, Penny. Everything you're saying is true, but please allow me to continue."

Penny nodded and braced herself for the friendship dissolving insult that Sheldon was about to throw at her. But he just turned back to Raj.

"Raj, you're out."

Sheldon continued to talk, explaining why Raj wasn't a suitable friend.

The relief made Penny feel weak. She had no idea the amount of weight she'd placed on her friendship with this odd man who lived across the hall from her.

A few minutes later, Sheldon restored Raj as friend and kicked the strange man with the speech impediment out of the apartment.

Later after everyone went home, Leonard turned to Sheldon. "So Raj, huh? I mean, don't get me wrong, but I'm kind of surprised Penny isn't the one you'd let go if you had to."

Sheldon gave him a horrified look.

"Are you kidding? I'd let you go before her," he said as if Leonard should have known that.

The shorter man just gave him his trademark confused look before shaking his head and going to bed.

After Sheldon settled himself in bed, he pulled out Penny's essay and re-read it. He smiled to himself then turned off the light.

Sheldon,

Despite this exam being at a high-school graduate level, I can not possibly hope to pass it. I don't know your favorite amino acid, who your role model is, or why string theory is the prevailing big bang theory.

I did graduate high-school, barely, but I don't remember much of the chemistry /physics I took.

Despite this lack of knowledge, I am your friend. I know you very well, and I can prove it...

I know that you have a special spot that is on the left side of the couch in your apartment. It is special to you because in the winter that seat is close enough to the radiator to remain warm and yet not so close as to cause perspiration. In the summer it's directly in the path of a cross breeze created by opening two windows. It faces the television at an angle that is neither direct, thus discouraging conversation, nor so far wide as to create a parallax distortion. I don't even know what a parallax distortion is, but I remember you using the words because I am your friend.

I know that Monday nights are Halo nights, Wednesday night's are comic bookstore nights, Friday nights are vintage video game nights, and Saturdays are laundry night.

You see sweetie, friendships aren't about knowing everything about your friend, it's about knowing the important things about your friend. And I am still learning from you every day.

I am sorry I couldn't be of more help. All I can say is that if this colleague at work doesn't recognize the value of being friends with someone as amazing as you, then he isn't worth your time.

Love always,

Penny