A/N: Hi everyone! I'm excited to share the first part of a new three-chapter collaboration I created with the help of my besties. The idea and framework are courtesy of Stellina2a.

A big thanks goes out to Platypus-Quacks-Too and Misschinitapr for help with the details and the laughs we all had bouncing ideas off each other.

Sheldon studied his fiancée as she slept in their dimly-lit bedroom. She looked so peaceful, so beautiful, with her hair fanned across her pillow. He longed to touch her but was afraid of waking her and releasing her odd behaviors. He had tried to fall asleep, but his concern grew the harder he tried. Seeking answers, his mind replayed the events of the last four weeks.

Amy had been acting completely normal when he flew to New Jersey to propose to her. He had missed her terribly, though she'd only been gone seven days, and realized he never wanted to spend another day without her. Once her initial shock at seeing him at her door on one knee with his great grandmother's ring wore off, she had ecstatically accepted. Her deafening 'Yes!' prompted her temporary neighbors to poke their heads into the hall to see what all the commotion was.

She excitedly shouted, "We're engaged!", and after assuring them everything was fine, she pulled him into her apartment, threw her arms around him, and kissed him as if her life depended on it.

When they finally came up for air, she led him to the bedroom. They were like wild animals in heat, ripping their clothes off and pawing at each other. For the first time ever, he had disregarded his need to neatly fold their garments, leaving them scattered along the floor. Amy had backed him up against the bed until he fell backwards onto the mattress. She straddled him with her nude body, and they had made passionate love.

He had planned to stay one week, then one week turned to two. As they headed into their third week together in the Garden State, Amy discovered the university's primary benefactor backed out, and her research fellowship abruptly came to an end. She had been disappointed but relieved that they could return home.

Sheldon brought his mind back to the present. Could that be the reason for her unusual behavior? It didn't seem likely, as he had witnessed Amy's disappointment before, and her behavior then was inconsistent with her current behavior. For as long as he had known her, she had never been lightheaded and forgetful when experiencing disappointment. But the strangest phenomenon occurred when he had rested his hand on her breast as he spooned her in bed, and she moved it to her abdomen, claiming she was very sensitive. Amy normally enjoyed that portion of their nightly routine, even when her day had not gone well.

He quickly tossed the disappointment theory aside and continued pondering. Was it just lingering excitement from their impending nuptials? That could explain the lightheadedness and forgetfulness, and he was no expert on biologic functions, but even he knew breast sensitivity was highly improbable. When they had engaged in frenzied lovemaking the night he proposed, had he somehow over excited her, causing her body to react adversely? Perhaps, but he would need more evidence to support his hypothesis.

He settled back against his pillow and consulted the alarm clock. In five short hours, they would be at work. He needed to be refreshed and focused, not only for his career but also to solve his fiancée's enigma. He began reciting pi to 1000 places and finally drifted off to sleep.

In what felt like only moments later, the alarm blared its annoying, pulsating beeps. Sheldon stretched his arm and hit the Off switch. He felt Amy stir next to him.

"Morning," she yawned.

"Morning. Did you sleep well?"

"I did." She blindly reached for her glasses and settled them on her face, propped herself up against the headboard, then quickly squeezed her eyes shut and hung her head.

"Amy!" He shouted, alarmed.

"Sorry, just a little lightheaded again. It will pass."

"I'm worried about you. This is the fourth consecutive day you have felt this way."

"I probably sat up too quickly. I promise I'll be more careful tomorrow."

He wasn't convinced but decided to drop it for now. He didn't need to add to her discomfort by badgering her further. When she reopened her eyes, he scooted over and slung his arm around her. His fingertips brushed her nipple through the thin cotton nightgown, and she shied away from his touch. Noting his hurt and surprised look, she pecked his lips.

"I'm still sensitive. My period is due any day."

"Of course," he replied absently, as his mind raced. They had been living together for months. In that whole time, she had been especially aroused right before her period; he knew because he tracked her cycle. She had always welcomed his hands under her shirt during these makeout sessions. Something wasn't adding up.

When she attempted to stand, he hurried to her side of the bed and offered his hand, pulling her up slowly. They padded to the kitchen hand in hand. Amy took a seat at the island.

Sheldon frowned. "I'm worried you'll fall off that chair. Maybe you should sit on the couch today."

"I'm fine now. The lightheadedness is gone."

"Please, Amy? It will set my mind at ease."

"Since you feel so strongly about it, I will." She stood then squeezed her eyes shut and leaned heavily on the counter.

"Amy!" Sheldon wrapped his arms around her waist and gently settled her in a seated position on the floor.

"I stood up too quickly. I'm okay now."

After proving she could stand without assistance, Sheldon reluctantly agreed Amy was capable of driving them to work.

xxx

Sheldon couldn't focus on his equations, so he used the time to do a little research. Causes for lightheadedness included abnormal heart rhythm, dehydration, hunger, being surprised, standing up too quickly, medication side effects, the flu... Next he researched causes of forgetfulness and finally breast sensitivity.

He stood back, chin in hand, staring at the differentials on his white board. There was some crossover between the first two syptoms, but the third appeared to have no connection. Curiouser and curiouser. His heart raced as another thought occurred to him. Maybe she picked up some sort of rare and incurable disease while she was working in that lab in Princeton. He had been so upset to see her leave that he hadn't even asked her for details. He willed himself to calm down until he had all the facts.

He was so engrossed in his thoughts that the soft rap at his door made him jump.

"Sheldon, are you okay?" His fiancée asked, as she crossed the threshold into his office. "When you didn't appear at my lab at noon, I started to worry."

He quickly flipped the whiteboard away from view. "I'm fine. I was just caught up in... a project."

"You sure? You look a little pale."

He consulted his watch. "Oh, dear Lord! It's almost 12:30. Why didn't you come sooner? Now we'll be lucky if the cafeteria still has the daily special."

"Sorry. I waited until I was pretty sure you weren't coming. You didn't forget, did you?"

"Sheldon Cooper never forgets," he huffed. "Unlike you recently," he muttered under his breath.

"What?"

"Nothing. Let's go."

To Sheldon's relief, they had not missed out on the special. He watched with interest as Amy piled her tray with soup, a sandwich, an apple, a bag of chips, a bowl of fruit, and a pudding cup. Never had he seen her eat this much food in one sitting. He shrugged it off to the later-than-usual lunch break and the fact that she had eaten very little at breakfast.

"Amy, exactly what sort of research did you work on at Princeton?"

She swallowed a bite of sandwich and took a sip of water. "We were trying to determine if any existing therapies would be beneficial in protecting the nervous system from further damage in patients with multiple sclerosis."

"It's a shame the funding was pulled."

She nodded in agreement while she chewed. "Why are you just asking me now?"

Sheldon shoved a fry into his mouth. He walked right into that one. He half expected her to wait for his answer before taking another bite, but she appeared to have already forgotten. He felt guilty. Here he was worried for her health and trying to figure out the cause, yet he was relieved her symptoms were working to his advantage.

xxx

Over the next four days, Sheldon continued monitoring Amy's behavior. Not only was she still exhibiting the same signs, new symptoms had surfaced. She was preparing beef loaf one evening and nearly passed out from the smell of the raw meat. He stood outside the bathroom door helplessly as she retched.

"I'm sorry, Sheldon. If you don't mind, I'm going to stay in here until the scent is gone."

"Amy, perhaps you should seek medical attention."

"I'm sure it's nothing."

"But..."

"No buts."

Not wishing to argue when she was obviously unwell, he squeezed her hand then proceded to the kitchen to finish preparing the meal. She declined the entrée, opting instead to eat the salad followed by a giant bowl of ice cream. He massaged her feet as they settled on the couch to watch Animal Planet, or rather she watched the show while he secretively watched her. She appeared engaged in the action on the screen, and the color had returned to her face. On the surface, she seemed normal, but he was so in tune to her body that he knew something just wasn't right.

At 10 o'clock sharp, he ushered her to bed. Normally on Friday nights, she persuaded him to stay up with her until 11, but this time she accepted his proferred hand without a word.

They kissed each other goodnight then snuggled under the covers. She sighed contentedly as he pulled her in closer, his nose burrowing in her hair. He cautiously slid his hand down to her breast and was nearly squished when she shifted suddenly, catching his head under her shoulder blade.

"Sheldon, not tonight," she hissed.

"I wasn't planning on intercourse tonight, just our usual pre-sleep routine. I miss it."

"I know, but I'm still sensitive." She softened. "I miss it too. I'm sure it will only be a few more days. I'm really tired, so I'm going to get some rest. I love you."

"I love you too," he whispered.

He waited until her breathing had slowed then gingerly extricated himself. Careful not to wake her, he tiptoed into the bathroom, gradually opened the medicine cabinet, and removed the thermometer. Now came the tricky part, taking her temperature without disturbing her sleep. He decided to place his hand on her ear to see if the light pressure elicited any reaction. If it did, he could pretend he had inadvertently touched her in his sleep. She didn't stir, so he went ahead with the plan. Moments later, the thermometer beeped, and he silently cursed himself for forgetting that function. Luckily, she continued to sleep soundly.

He peeked at the reading: 37.8 C, higher than normal. When they had first started living together, he would routinely take her temperature and noted it was higher when she was menstruating, which she currently wasn't. He thought back to the differential chart he created on Monday. Was it possible one of the sypmtoms of those diagnoses was elevated temperature?

Climbing out of bed again, he padded to the living room and flipped open his laptop. He typed 'elevated body temperature causes' in the Google search bar. Millions of entries populated, and he soon learned there were several reasons a person's body temperature could rise above normal. He began cross referencing them with all of Amy's symptoms, but none of the diagnoses matched with all of her symptoms, that was until one word popped out at him - pregnancy.

Could it be? He thorougly reread the entry. Every one of her symptoms could be caused by pregnancy. But how could that have happened? They were always so careful and had only engaged in sexual intercourse twice in the last six months, the night before she left for Princeton and the night he proposed. The first time they had used protection, but the second time... They used protection, right?

He thought back to that fateful night. They had been too engrossed in each other, both from the excitement of their impending nuptials and from reuniting after their short separation. When Amy had straddled him, he had almost wanted to forego the foreplay. He needed her that badly. When she was ready for penetration, protection was the last thing on his mind.

He thought about it some more. Pregnancy was a possibility, but unprotected sex didn't necessarily mean they had procreated... except there was another detail he had overlooked; her period was overdue.

He always figured he'd be afraid when and if Amy ever became pregnant, but he was ecstatic. Not only would they soon get married, now they would also be welcoming new life into the world, a product of their superior combined DNA and their great love for each other, their very own homo-novus they would offer to humanity. He couldn't wait to tell her his findings.

He stood and hurried to the bedroom, about to shake her awake, but drew his hand back just in time. Amy was not going to be happy about this. She made it clear when he had wanted to procreate with her after they successfully converted their skin cells into functional brain cells.

He slipped under the covers but was too excited to sleep, so he opted to watch her chest gently rise and fall with each inhalation and exhalation. The rhythmic pattern was soothing. Just as he felt ready to drift off, another thought occurred to him. She was only in the earliest stage of pregnancy and already had a multitude of symptoms. How would she cope a month from now, two months from now, three months from now... It was only going to get worse for her, and it was all his fault. How could he have been so stupid? He had allowed his baser urges to take over his body and for what? One wild and crazy night? His mistake was going to cost them both dearly.