AN: So, 'Four Months' is now being split into 3 parts. This part went long, and I really liked leaving it where I did (you'll understand), because Derek needs to get the last word occasionally...

With a smirk on her face and a large cup of coffee in her hands, Meredith pushed through the heavy wooden doors of the lecture hall and quickly ducked into one of the back rows. Her husband had been teaching at UW for almost two months now, and still had yet to invite her to one of his classes.

Meredith was now taking matters into her own hands.

She hadn't told him she was coming, and so had to stay hidden as long as possible. The class was scheduled to begin in less than ten minutes, but the lecture hall was mostly full. Derek was down at the front, conversing with a few students. Meredith smiled as she watched him nod along to whatever it was they were discussing. Teaching was definitely his element.

Derek paused in his conversation and turned toward the crowd. Meredith winced and hurried along the back row of seats, quickly plopping down next to a dark haired girl with a coffee that matched hers. She kept her eyes trained closely on Derek, and allowed herself a triumphant smile when he looked away from the crowd. She had flown under his radar.

"I haven't seen you here before."

Meredith glanced to the girl next to her. "No, I uh..." She trailed off, struggling for a valid reason to be there. It had never occurred to her that her presence would be questioned by a med student.

The girl shrugged. "It seems to be a pattern with this class; every week there seems to be more people."

Derek hadn't mentioned that to her. "Yeah, well," she stammered, "Neurosurgery. It's interesting."

"I think its Dr. Shepherd that everyone finds interesting. The majority of the newcomers are female."

Derek definitely hadn't mentioned that.

"I used to sit closer to the front, but I couldn't stand the whispers and gaga eyes some of the girls were sending him. It's quieter back here. I can enjoy the material." She shrugged. "Not that Dr. Shepherd isn't easy on the eyes..."

Completely void of anything to say, Meredith nodded absently and took a sip of her coffee.

"I'm Tracy, by the way."

"Meredith." She shook Tracy's hand.

"What year are you in?"

"Uh, I'm not so much in med school as I am...uh... I guess you could say I'm auditing the course?"

Tracy raised an eyebrow. "Is that a question?"

Meredith laughed. "It's kind of a long story. What year are you in?" She asked, getting the focus off of herself.

"Third. Past the half-way point, finally. Really looking forward to placement next year."

"Yeah, that's fun. You don't get to do or say anything, but it's still fun."

"You sound like you speak from experience."

"I finished med school a few years ago."

Tracy furrowed her brow. "Then why are you auditing a course? I can't wait to get out of school. When I graduate, I doubt I'll ever want to see another lecture hall or classroom again."

"That's part of the long story."

"Duly noted."

Meredith smiled. The girl reminded her of a cross between Cristina and Izzy; intuitive and straight forward, mixed with curiosity and openness. "Where do you want to specialize?"

"Surgery. I always thought it would be internal medicine, or that I'd fall in love with non-surgical specialty. But the surgeons who teach here are so much more enthusiastic than anyone else. It's kind of contagious."

Meredith nodded. She could remember one professor in particular from Dartmouth, an aging orthopaedic surgeon, who had a habit of going off on long tangents about surgeries he had performed over the years. His enthusiasm for orthopaedics made Callie seem dull and disinterested.

"How about you? What did you choose?"

"Surgery."

"Which subspecialty?"

"I haven't declared yet. I'm a third year resident, so I don't have to declare until the end of the year. But I'm pretty sure it's going to be neuro."

"Explains why you're here."

Meredith nodded, and took another sip of her coffee, covering for herself as she sighed in relief. Not only had she flown under Derek's radar, but Tracy's as well.

"Although," Tracy continued, a sparkle in her eye, "Dr. Shepherd's wife is also a surgical resident."

Meredith almost choked on her coffee. Maybe she hadn't flown under Tracy's radar.

"Her name's also Meredith."

She definitely hadn't flown under Tracy's radar.

"Fine; you caught me. He hasn't let me come to a lecture yet, so I snuck in- Wait, how do you know about me?"

"He talks about you," Tracey said simply.

"In his lectures?"

She nodded. "All the time. He uses a lot of case studies, tells a lot of stories. And most of them involve 'my wife this' and 'my wife that.'"

Meredith glared at her husband from well over a hundred feet away. "I'm going to kill him."

Tracy laughed. "He doesn't say anything bad. Although he has told us that you are specializing in neuro..."

Meredith had to laugh too. "Yeah, that doesn't surprise me. He's been pushing neuro on me from day one. Not very helpful when I'm supposed to be getting experience in everything. Especially with his sister pushing general and his best friend pushing plastics..."

"Mark Sloan?"

"Yeah, how did you know?"

"He mentions Dr. Sloan a lot too."

"Oh, that's...strange..."

Tracy laughed. "He likes to tell us, at least once a class, why neuro is better than plastics."

"Okay, not so strange anymore." She pursed her lips. "Did he tell you about Mark and the ugly bowl?"

Before Tracy could respond, Derek began his class.

"Let's get started," he called from the front of the lecture hall. The class immediately grew silent, lending him their collective attention.

"I know midterms are right around the corner, and I'm sure everyone is eager to get away from here and back to their studying..." He laughed good naturedly with the class. "Anyway, I thought we'd use today's class to review as much material as possible. I have a number of case studies lined up, that we're going to go over from beginning to end, and see if anyone can solve them."

"Do we get bonus marks on the midterm if we solve them?" A male voice from somewhere near the front called out.

Derek chuckled. "I'll tell you what; I'll put a case study on the exam, and if you get that one right, you'll get some bonus marks."

Everyone nodded their agreement, and Derek proceeded – with only minimal struggle – to open his powerpoint presentation onto the large screen above him. "Okay, let's have some fun."

"Fifteen year old female, presenting with new onset seizures, intermittent for one week. What do we need to know?"

"What kind of seizures is she having?" Called out a student near the middle.

"Good question," Derek replied with an approving nod. "Grand mal." He pressed a button to display the basic information on the screen behind him.

"Do the seizures respond to medication?" Another student called out. It seemed to be a pattern. Derek ran his lecture hall like a small, interactive lab group.

He nodded again. "Currently, yes. Diazepam."

"Any problems with other vitals?"

"Not currently. Patient is breathing on her own. Pulse and PB are normal. What do we do next?"

"EEG. Fifteen is older than most are diagnosed with epilepsy, but still common enough."

"Who says it's epilepsy?" Another student argued. "She's a teenager. I say it's drugs. Run a tox screen."

"Or it could be a tumour," said another. "Run a CT."

"No, run a CBC and chem-7. This could be as simple as an infection or metabolic disorder."

"She could have a birth defect."

"That didn't show up until she was fifteen?"

"It's possible."

"But not likely."

"Okay!" Derek called, holding up a hand. "You all have valid points. Don't fall into the trap of assuming every seizure you see is epileptic."

"Are you saying this one wasn't?"

Derek pursed his lips, and then nodded. "For the sake of moving through this case study I will tell you it isn't. When we ran the EEG, it was negative. But we didn't run it first. Can anyone tell me what we did run first?" He held up a hand before anyone cut him off. "And keep in mind that you can't run every test at once."

"Tox screen."

"CBC."

"CT."

"Chem-7."

"Scans take time to get," he reminded. "So we start with what we can get. And that includes a tox screen, CBC and chem-7. Now, what are we looking for in the tox screen? What drugs would cause seizures?"

"Amphetamines."

"Good. What else?"

"Cocaine."

"Also correct, but what else?"

Silence.

"Come on, you guys know this. Stop thinking only illegal drugs."

"Certain medications."

"Good. Like what?"

"Chlorpromazine."

"Certain medications used in treating mood discorders."

"Some antibiotics."

"Cyclosporine."

Someone scoffed. "I doubt the patient is on anti-rejections drugs. Fifteen is a little early to have gone through an organ already."

"It could have been a familial defect. She may have had a transplant when she was a baby."

"And just started seizing a week ago?"

"Maybe her medication was changed."

"Or maybe she screwed up a dose."

"Good; you're thinking now. Don't ever forget about the history. Always ask questions."

"So, we're right?"

"Not even close."

"Then why ask us?"

"To make you think. Sometimes diagnosing is about ruling out as much as you can. For the record the patient's seizures were not caused by any drugs or medications. But we also ran two other tests. What was the point of the chem-7?"

"To look for metabolic issues."

"Good. Like what?"

"Abnormal levels of sugar or sodium."

"Or calcium."

"And magnesium."

"What about creatinine? Or other liver and kidney enzymes. Liver and kidney failure can both cause seizure activity."

"Again, she's a little young to have gone through an organ."

"Plus, I doubt her tox screen would be normal."

"Alcohol and drugs aren't the only reason organs can be damaged. Genetic disease. Infection. Physical damage. We should take a DNA sample and have it tested for markers."

"You're thinking, but you're getting ahead of yourselves. Her chem.-7 was unremarkable."

"What about her CBC?"

Derek smiled. "Good question. What result were we most interested in?"

"Her white count."

"Good. Why?"

"High white count equals infection. And infections can lead to seizures."

"Excellent."

"So, that's it? She has an infection?"

Derek shook his head. "Nope. Her white count was normal; as were the rest of her CBC."

A collective groan was released.

"What do we do next, assuming we've ruled out epilepsy?"

"Run a CT."

"CT was clear."

Silence.

Derek smirked. "I guess this is a good time to tell you that this patient was transferred to my hospital, because the first hospital she was treated at couldn't diagnose her."

"Then it has to be something rare. Run the genetic markers."

"We don't have time to wait for the results. Less than a day in our hospital and her heart stopped during a grand mal seizure."

"There are a number of diseases she could have that wouldn't necessarily increase her white count. Meningitis, or encephalitis."

"Or tetanus."

"Rabies."

"Syphilis."

"In a fifteen year old?"

"It's possible."

"AIDS."

"Has she been out of the country? Malaria can cause seizures."

"Excellent points. But you're all wrong. You're missing something."

Silence reigned again, as everyone struggled to come up with the solution. Meredith smirked to herself as she sat back in her chair. The answer seemed so obvious now.

"You know the answer, don't you?" Tracy whispered. She had been scratching notes onto her pad of paper, and then violently crossing off possibilities.

Meredith nodded.

"I kind of hate you right now."

She laughed. Tracy was definitely reminding her more of Cristina than Izzy.

"Are we stuck?" Derek asked.

"I get that you're making us think, but how are we supposed to solve this? We're just med students, and you've been doing this for years."

"I didn't solve this case," Derek admitted. "I was as stuck as you were. The patient's vitals were getting worse, she was no longer responding to her meds, and I couldn't diagnose her. And without a diagnosis, I couldn't treat her."

There was a pause. "She didn't die, did she?"

He shook his head. "No, she didn't die. I was approached by a very remarkable intern, who took the time to listen to the patient." He smirked and lifted his eyes up, not hesitating as he looked right to Meredith.

Meredith felt a whoosh of air leave her lungs as Derek met her eyes for an extended moment. Apparently she hadn't flown under anyone's radar. He smirked again, raised an eyebrow and then went back to his class.

"How does he possibly know I'm here?" She hissed.

"Were you the intern?" Tracy asked.

She nodded. "It was a fluke, really..."

"I'm a little disappointed," Derek was saying. "None of you have asked for any recent history. We have a fifteen year old who is dying, and yet was perfectly healthy a week ago. This is something new. Something our tests haven't been able to pick up."

"If anything major happened to her a week ago, you would have told us."

"I didn't tell you anything more than I was told. Never fall into the trap of assuming you will be told what you need to know. Always take an interest in your case; always ask questions. These questions save lives."

"Did she suffer an emotional trauma a week ago? Sometimes emotional distress can be manifested physically."

"No emotional trauma. But she did trip during a rehearsal for...some dance thing she did."

"It couldn't be trauma, or the CT would have picked it up."

"What if it was something the CT couldn't pick up?"

"What's the point in getting a CT if a clear scan doesn't mean nothing is wrong?"

"Because most of the time, the CT will find it. Trust your tests, but if you run into a brick wall, you need to take a step back and ask what could have been missed. Go back to okum's razor. She's young, and was previously in good health. She's not on drugs, or taking any medication. All of her labs were clean."

"It's got to be something neurological. Have we done a spinal tap?"

"Spinal tap was clear."

"So it's something physical."

"And small enough that the CT couldn't pick it up."

"A tumour?"

"But she had a fall right before the seizures started. Odds are that's not a coincidence."

"An aneurism," a student said suddenly.

Another nodded. "A small one; so small it wouldn't have been caught on the CT."

"Something she probably had from birth."

"But the odds of something like that being dislodged is-"

"One in a million," Meredith whispered, as her husband announced the same odds to the class.

"And Okum's Razor tells us to consider everyone within the nine-hundred and ninety-nine thousand, nine-hundred and ninety nine people whose aneurisms wouldn't have dislodged, but everyone once in a while you will run into this. It shouldn't be your first thought, or even your second or third, but it should always be in the very back of your mind, just in case."

"So, what happened to the patient?"

"You tell me. How would we have diagnosed?"

"Angiogram."

"Exactly. Angiogram showed a very minor sub-arachnoid haemorrhage. We caught it in time." He smirked. "The patient wasn't happy that surgery involved shaving her head, but the surgery did save her life. Which is another reason neuro is better than plastics; our patients may not come out of surgery looking better, but we save lives."

The class laughed at his insistence. Obviously the neuro versus plastics thing was quite regular.

"Anyway, we were completely successful, and the patient went back to her dance thing. In fact, I got a letter from her a year later, after her hair had grown back, telling me that she had won her pageant with her dance thing."

"It must have been awesome, that you saved her."

He smiled. "It was pretty amazing." He looked up to meet Meredith's gaze once more. "Quite the high."

She smiled softly back at her husband, remembering how awkward things had been between them that day. How humiliated she had been when she had first spotted her one-night stand in the hospital. How determined she had been to stay away from him, to resist his charm.

"And an intern figured this out first?" A student asked, pulling Derek's attention from his wife.

He nodded. "During her very first shift."

"Impressive," said a male voice. "I'd kill to be the intern."

Derek smirked. "I'd have to admit that I'm glad you're not. You see, I ended up marrying her, and you're not really my type."

The class laughed.

"My wife seems to think she's always right," Derek continued. "But my next case also involved her. And this time I was right."

With one last smirk upwards to his wife, Derek presented the case.

"Male, early forties, presented with spreading paralysis after a short fall rock climbing..."