A/N: My first one-shot! Don't ask me why but I was so intrigued by Sheldon's statement in the Prom-episode and I just had to write my own version of his thought process. I hope you enjoy it!

- YlvaB

The Parasitic Infestation Hypothesis

By YlvaBorealis

Green was one of his favorite colors. Green as in Green Lantern and Green Arrow. The endless forests of Azeroth were green, as was the icing on his grandmother's Christmas cookies. Those that tasted like the warm embraces he remembered from his childhood.

As Sheldon Cooper looked into the expectant eyes of his girlfriend Amy Farrah Fowler, he found himself thinking that they were a shade of green he'd never seen before. Like emeralds with little flecks of amber in them, precious stones that glimmered with anticipation and something else… Something he hadn't quite identified yet.

"Well… goodnight then Sheldon" Amy said, her deep contralto vibrating through his body.

"Goodnight Amy" Sheldon let out, still enchanted by the rich timbre of her voice. Husky, rumbling, and at times fragile – ah, he didn't know what it did to him, but it sure did something.

She was still looking at him with those dark green eyes of hers, biting her lip as she put one hand on his elbow and the other at the nape of his neck, standing on her tiptoes as she pulled him down for a kiss.

He grabbed her by the hips, supporting her as her lips softly brushed his, marveling at the softness of her body and the sweetness of the fact that she was so petite in his arms. If he'd wanted to, he could have rested his chin at the top of her head.

He licked his lips as she broke away from him, noticing how they tasted of peppermint. She'd had peppermint tea. 'Peppermint chemically triggers the TRPM8 receptors in the skin which are sensitive to cold' Sheldon thought, enjoying the chilly sensation as his breath touched his bottom lip.

All of a sudden he found himself alone in the living room. When had she left? They had kissed goodbye, that much he remembered, but he couldn't recall her walking out the door. She must have, obviously.

'What is happening to me?' Sheldon thought as he went over to the couch to sit down in his spot.

He had always known Amy Farrah Fowler triggered something within him that no one else did. Sheldon Cooper was a man of science, a theoretical physicist, a former child prodigy, one of the greatest minds of the 21st century. There was nothing he wouldn't say or do: after all, emotions were nothing but chemical reactions in the brain: the result of millions of years of evolution based on trial and error, where nature had finally concluded that empathy was a biological advantage. You scratch my back, I scratch yours so to speak.

He couldn't argue with the evidence: after all, nature had conducted a scientifically valid experiment, even he couldn't argue with that. But he was beyond evolution: a Homo Novus. Sheldon Cooper, the Next Generation.

Sheldon Cooper, whose favorite color was emerald green.

"Oh, stop that!" he exclaimed to no one in particular. His brain, possibly. His brain hadn't exactly been cooperating with him lately. Come to think of it, it hadn't been cooperating with him for a very long time.

'This is insane' Sheldon thought as he rose to get one of his whiteboards and his box of markers. 'It can't be that. Anything but that. Surely there must be some other explanation'.

He pulled the cap off of one of the markers, writing 'Symptoms' in the far left corner, and 'Possible afflictions' in the far right.

"Alright, let's sink this ship once and for all" Sheldon mumbled to himself as he began making a list of what had troubled him lately.

'Let's see: insomnia, disturbing dreams, excessive sweating, shortness of breath, feeling as if your personality has been split in half, nausea, erratic behavior, loss of… control of certain body parts' he thought to himself, deciding not to include that last symptom in his list.

"Yet another disturbing symptom: shame" he snorted, feeling ridiculous about his own discomfort. He was alone, for crying out loud! Leonard was asleep in his room, Amy had left half an hour ago. No one would know.

He still couldn't bring himself to write it down.

"Possible afflictions… sch-i-zo-phre-nia" Sheldon wrote, deciding to use a red marker. What was life without a little flare and color?

Schizophrenia. A mental disorder characterized by bizarre delusions and hallucinations, and the inability to organize one's thoughts and feelings. Even though Sheldon had a profound understanding of everything in the Universe, he had to admit psychology wasn't his strongest feat. He looked around the living room, spotting his laptop on his desk. He'd have to do some research.

'Let's see, schizophrenia…' he typed, surprised at the millions of hits he got. Could so many people be feeling the exact thing he was feeling right now? It seemed highly unlikely, but what did he know.

"Schizophrenia is often misinterpreted as multiple personality disorder, popularized in movies and TV. It's largely believed to be a genetic disorder that can be triggered by social factors such as severe psychological trauma. Patients often start displaying symptoms at the onset of puberty. A person suffering from schizophrenia may have trouble maintaining their personal hygiene" Sheldon read out loud, scrunching his eyebrows. Well, that certainly didn't sound like him. No one in his family suffered from schizophrenia, at least not to his knowledge… Although there was that uncle of his who insisted on sitting under the table every year during Thanksgiving, only coming out to get more mashed potatoes and cranberry sauce.

Sheldon shook his head. Whatever he had, it wasn't schizophrenia. He got up to erase the red letters from his whiteboard, ruling out 'mental disorder' as the cause of his troubles.

Green forests. Green Arrow. Amy's emerald green eyes.

"For crying out loud!" Sheldon pressed out through gritted teeth, refusing to allow these disturbing thoughts to snake into his head. His lips still tasted of peppermint, a fact that only served to fuel his agitation. They had kissed, just as they always did at the end of every date night. She had suggested they make it a regular occurrence after he had kissed her for the first time last Valentine's Day, and he had been surprised to find he was just as eager as her to make it part of their Relationship Agreement. There had been no argument, no counter-proposals… all he knew was that he didn't want to go back to the time before that kiss. His lips had sought hers hungrily, almost of their own accord, and his pelvis had been pressed into hers, stirring up emotions within him he still hadn't entirely deciphered. Before that day, he'd been somewhat aware of the possibilities behind such a move, but after that day… oh dear.

'Focus Cooper, focus' he told himself, once again repressing the thoughts that ate at him. He looked at the list of symptoms, getting up to get one of Amy's books on Biology.

Amy. Emerald-eyed, dark-haired, petite Amy with her rumbling contralto. Amy.

'There must be something in here, please let there be something in here' Sheldon pleaded with the book, furiously browsing the leaf-thin pages.

"Aha!" he exclaimed, finally finding what he was looking for. "Tape worm. This must be it" he mumbled to himself, sitting down on the couch as he frantically searched the chapter for something that might indicate that he was indeed infested by some sort of parasite.

"Tape worm… intestinal parasite that can grow up to… oh dear…" Sheldon mumbled, feeling the nausea creep up on him. "Some species infect the brain and can occasionally peek out through varying bodily orifices such as the mouth, the eyes – huaaaaaaack" he gagged, slamming the book shut, clasping his hand over his mouth. Oh, dear, oh dear, oh dear, oh dear.

He ran into the bathroom, feeling certain he'd be praying to the porcelain God. "Okay, so no brain parasite" he groaned, resting his forehead on the toilet seat as his stomach slowly settled down. Thank God he'd been able to hold it in.

He slowly rose on slightly wobbly legs, making his way back into the living room. There it was, his whiteboard… tantalizing him.

"What are you looking at?" he muttered at the inanimate object, not even caring he was acting like a crazy person. His mother had him tested after all, there was nothing to worry about.

He picked up one of the green markers. Green again. How was it that he kept coming back to those green eyes of hers? That woman…She did things to him. Why did she have to be so much like him? Why did her lips have to be so soft? Was it really necessary? Her lips could do their job without being so…. Supple and beckoning.

Supple and beckoning?

His hand rose almost of its own accord. As if it were possessed, it began writing, and his heart was pounding so hard he thought his ribs would crack. There it was. That word. That word he'd been desperately avoiding for the greater part of his life. Bright green, like her eyes.

Could it be true? Could this be the only conclusion?

He put the tip of the marker in his mouth, quietly suckling it as he kept staring at the letters, cringing as the bitter taste of the ink violated his tongue. He hated those scented markers.

Sheldon closed his eyes, trying to erase the image of that word, but it was burned into his retina. Curse that eidetic memory of his. Curse this warm, fuzzy feeling.

Green. Emerald green with little flecks of amber.

"Is It really so hard to believe?" her voice whispered in his ear. Her voice. Her low, rumbling, sexy voice. Sexy. Sex. She wanted to have sex with him. He wanted to have sex with her. He'd never wanted to have sex with anyone in his life. But she wasn't just anyone… She was Amy. A female of his species. A fellow Homo Novus.

Suddenly, Sheldon heard someone entering the kitchen. Leonard. What time was it? He checked his wristwatch: 6.30 a.m. Had he been up all night?

"Hey buddy" Leonard greeted, making his way to the coffee maker. His hair was askew and one of his socks was pooling around his ankle. The bespectacled physicist pulled out a mug from one of the cabinets, busying himself with making breakfast.

"Did you wake up early or have you been up all night?" Leonard asked as he began measuring coffee beans and filling up the machine with water, noticing how Sheldon was already dressed.

"I've been up all night" Sheldon replied, still staring at that word.

"Oh? Have you been working? What are your conclusions?" Leonard asked, somewhat concerned.

Sheldon turned away from the board, meeting Leonard's hazel gaze.

It was the only conclusion. He wasn't schizophrenic. There was no brain parasite. There really was only one explanation.

"I love Amy Farrah Fowler" Sheldon let out, a strange tingling spreading through his limbs. So warm… So soft.

Leonard looked back, the corners of his mouth curling upwards ever so slightly.

"I know" he said, returning to making breakfast.

Sheldon nodded, and put the cap back on the marker.

Quietly he regarded the green letters on the whiteboard, realizing they both terrified and excited him. 'There really is only one conclusion' he thought as he allowed his blue eyes to trace the word that had previously tantalized him. It was there, as if it had been there since the beginning of time.

'LOVE'.

THE END