Disclaimer: I don't own this show. Please read the author's note at the end.

As surgeons, we are constantly being blindsided, constantly facing the unexpected so much so that eventually you start to predict it; start to welcome it. We're raised to be scientists, to be mathematicians, to decipher-to know. The unknown doesn't scare us instead, after a while, it starts to feel almost comforting, almost needed. Yet sometimes, sometimes what the future has in store, surprises even the best of us. Sometimes the future defies all laws and patterns and we're left with nothing but ourselves to fall back on.

She was late. So late.

She could almost see it- him with his infuriating smirk, waiting for her, a look of victory in his eyes.

If she could just run faster. She almost regretted not listening to her mother when she'd suggested joining the track team in high school. Almost.

Meredith turned a sharp corner, narrowly missing a code blue team.

"Hey!", Cristina yelled catching up to her, straightening the lapels of her coat.

"What?"

"Could you..maybe walk like a normal person?"

"I'm late."

"For what? Your period?", she asked, letting out a chuckle.

"You're not funny."

"I can't believe you slept with him. Again."

"It was a momentary lapse in judgement."

She loved Cristina, she did, but right now? Right now she was just coming in her way and honestly, she didn't need this right now.

"I'm late and I can't be late", she made a turn and could finally spot the resident's lounge. Almost there.

"Oh, this again? It's been going on for five years. When are you gonna get over it?", her person muttered, retrieving a granola bar from her pocket.

"I have to go.", she slightly glared at Cristina who shrugged and made her way towards the cardiothoracic department as she rushed inside the lounge.

"You're late."

"Damn it.", she muttered, facing the source of the statement; the source of most of her problems and most definitely, usually the source of her rage.

He stood facing her with, just as she'd predicted, that ridiculous smirk, his head tilted, leaning on his cubby, one hand in his light blue scrubs' pocket, the other holding onto his old, brown diary.

"So that would make the score...16:10? Yep", he said, opening his diary.

"Right, I forgot that 50-year-olds have to write things down."

Meredith moved beside him to gather her scrubs from her cubby.

"Huh. 10 minutes, Grey. That's a record. Even for you. Long night?"

The dark circles. It had to be the dark circles. She should have used the damn foundation but with, throwing him out in the morning to rushing for work, it had slipped her mind.

Rule 1: Never show any weakness. Never let the other know.

"None of your business", she snarled as she hurried beside him to change into her scrubs.

"And you know, some of us actually have a life.", she turned to face him, her eyes never leaving his blue ones as she began to pull off her top.

"Well, I'm in the lead. Not that that's a surprise", he said, clearing his throat and moving to fetch his coat. She could see a slight blush move over his features and she couldn't help the sly grin that adorned her face.

She knew that she was making him uncomfortable or specifically, she knew that her partial state of undress was making him so.

Over the past five years, this was something about him that she hadn't been able to figure out.

Maybe someday she would. She would have to-in order to destroy him.

"Well, I'll be in the ER. Don't call me if you need anything.", he sang as he headed out.

God, she really did hate him.

She had, for the past five years.

Meredith Grey and Derek Shepherd were enemies, competitors- call it what you want.

Meredith Grey and Derek Shepherd hated each other.

They had ever since their first day as interns and everyday since, had been a carefully thought out plan to one-up the other.

The being on time thing was a part of it and Meredith, who had never been an early riser, had always lagged behind. But not in the other ones. Never in the other ones.

Every part was a competition -from OR time to leaves taken; from mortality rates to streaks- everything was carefully recorded and analysed. In Shepherd's old diary. For him. She used her phone to record it, just like any normal 21st-century individual would.

She needed to get ahead of him.

After all, the race for chief resident was about to begin and not in a million years would she let-Derek freaking Shepherd with his smirk and his coiffed hair-win.

"What are you guys talking about?", Izzie asked, suddenly appearing beside them at the nurses' station, a half-eaten bagel in her hand.

"Um, nothing-", Meredith said, avoiding her gaze.

"Is it about you sleeping with Michael again?", Cristina chuckled loudly earning a glare from Meredith.

"How did you-?"

"Oh, we live in the same house. You should have learned by now, Mer."

"I mean it's getting a little pathetic now", her person muttered, sharing a look with Izzie, similar grins plastered to their faces.

"Oh, shut up. Like the two of you are any better. And it only happened because I had had a bad day and he was..right there."

"Mer, you wanna sleep with someone sleep with a surgeon-enough with the ER-resident; they're not even real doctors.", Cristina scoffed, pulling her dark waves into a messy bun.

"Michael isn't a resident anymore."

At the pointed look, she received from her friends, Meredith couldn't help but groan loudly.

"Shut up. I hate you both."

"Oh, you love us", Izzie smirked, a glint in her eyes and Meredith ripped the bagel from her hands, eliciting a string of protests from her.

"Chart for Peter Davies please, Tyler."

She watched the nurse rummage through his stack before presenting her with the lime coloured folder.

He was here. She could feel him-recognized his scent; that particular cologne she'd burned into memory. A whiff of pine. She'd always assumed that was what it was.

Rule 2: Always be aware of the other's presence.

He was now, right behind her, their backs to each other as he gently talked to someone, presumably a patient's family-quietly explaining their condition, a warmth emanating from him- warmth she was unfamiliar with.

Izzie and Cristina continued their discussion around her as she riffled through the file, antsy to begin her rounds, to get away from here.

"A medulloblastoma. Finally, my day's looking up.", she mumbled, her gaze fixed to the scans. It was a beautiful tumour, intricately wound- one she knew she would have fun with.

Well, this was certainly a healthier pick me up than what she'd prescribed herself last night.

Just another thing she needed to deal with.

"Really? Show me. I'm stuck in the clinic today. I need a tumour. Or sex. Really need some sex", Izzie rambled on as Meredith flipped through the chart again.

"Petey's in the hospital?", Derek said, rushing to her side, his breath on her shoulder as he moved to take the chart from her hands.

"Hands. Off. Shepherd. This is my case."

"Just give me the chart, Grey.", he tugged it forcefully but Meredith resisted.

"No, I'm on neuro this week. My case."

"Just let me see if it's-", he muttered, his voice had lost all the gentleness from earlier as he finally managed to snatch the scans.

"You did not just!"

Somewhere during their tussle, her friends had fled from the scene, leaving her to deal with him alone.

"Why are you on his case?", he flipped through the stack, agitated- a look akin to panic in his eyes.

"Excuse me?", she yelled. "Look, Shepherd, I know you like to think that you're God's gift to humanity but this, this is my case so back off."

"No, this is my case."

She wanted to punch his lights out. Instead, she gritted her teeth and moved closer to him, ready to begin the game of tug-of-war again.

She wouldn't let up, not with him.

This was her case and she wouldn't let it go.

"Hey, you two!", Meredith heard a loud wail directed towards them causing her to look sideways only to come face to face with the 'Nazi'.

"Dr Bailey he is stealing my-"

"No, it's my patient-"

"I'm on neuro, he isn't-"

"Hey! Look at me. Grey, Shepherd. Does it look like I care?", she glared at them, hands on her hips, a fierce look in her eyes. "Whatever it is- take it up with your attending. I do not need bickering children in my hallway.", she pointed at them.

"Did I not make myself clear?"

Both of them nodded their heads in affirmation yet Bailey stared at them with pinched eyebrows, motioning for them to clear the passage.

She had to reach before him. She had to.

Meredith took off in the direction of the elevators, determined to reach Dr Martinez before him.

As soon as he caught up with her intentions, he was hot on her heels. He had five inches on her, it was only a matter of time before he sprinted past her. She understood this so she picked up her pace, slyly running into the intern with charts in his arms, knocking them to the ground causing Derek to halt for a moment.

She deftly entered the elevator, doing a small, happy dance in her head, pushing the button for the 3rd floor when a lean arm stopped the doors from closing.

Derek entered, cheeks flushed, his chest rising and falling rapidly as he scowled at her.

Damn it.

They spent the elevator ride in silence, an uncomfortable tension between them.

She pushed past him, squashing the guilt she had felt creeping up on her.

Rule 3: Never feel guilt or remorse towards the other.

He followed suit, much slower somehow.

Meredith entered Dr Martinez's office and found him sitting behind his desk, his fingers rubbing his temples.

"Grey.", he said, acknowledging her presence but not looking up from his laptop.

"Dr Martinez, I'm on your service this week."

"I'm aware."

Shepherd quietly joined them, files still in his hands.

"Pete Davies is back." he muttered, fixing his stare on their shared mentor.

"I'm aware of that too."

"Why didn't you-", Derek began, confusion etched on his face.

"Look, what is the problem?"

"Dr Shepherd stole my patient's chart.", she growled.

"I've been working with him for the past two years! I know his history, his family- I know him. I should be on his case!"

"But you're assigned to the ER today! Hence making him my patient."

"Okay, enough.", he shouted, annoyance radiating off him as he cut them short.

"How about the two of you work together-on Peter's case?"

He was met with stunned silence, their breaths the only sound in the small room with the head of neurosurgery looking at them expectantly.

"Look, Peter's tumour- it's not the easiest and the two of you are by far, the best residents I've got. So work together; work for him. He needs all the help he can get.", Liam stood up, fixing his gaze on them, a painful look in his almond-shaped dark eyes.

"Fine.", Derek mumbled, his voice hoarse.

She hadn't expected his assent and most definitely not one so quick.

They didn't work together- as a rule.

They could barely even stand each other.

"Grey?"

"Sure.", she found herself agreeing on to this nightmare.

"Good, then it's decided."

The residents silently turned to leave the room when their attending said, "And I do mean work together."

Derek continued to exit the room, ignoring his words.

This was going to be a disaster.

A 9.0 Richter level worthy disaster.

She just hoped that Dr Martinez had a damage control team ready.

Because Meredith Grey would absolutely not let Derek Shepherd pluck this case from her.

Whatever that may entail.

A list of times Dr Meredith Grey and Dr Derek Shepherd have worked together:

Intern year:

Both were assigned to work on the decoration of the Chief's niece's prom-it ended up in an intense argument with no props actually arriving- until Dr Bailey had intervened.

2nd year of residency :

Both were assigned to the same practice dummy in the skills lab by Dr Carmichael, in hopes that it would help resolve their issues- the day ended with a mangled dummy being rolled out of the lab.

2nd year of residency:

Both were delegated the task of splitting the interns so that George could be assigned his share- resulted in a fight breaking out in the cafeteria with two interns leaving the area in tears.

3rd year of residency:

Both declared neuro as their speciality- constantly battling for OR time causing Dr Nelson(the former head of neurosurgery) to resign from his position as the department head.

4th year of residency:

Both were given the responsibility of creating the initial documentation of Dr Torres' clinical trial leading to a conflict of ideas between the idea wherein Dr Torres had to stay at the hospital the whole night to view both presentations.

Somewhere along the way, the attendings had unanimously decided on never letting them near a patient together.

It seemed that they were, after all, incapable of working together as a team.

So they had been kept apart.

Until now.

A/N: hello! I had definitely not planned on starting another story but damn, here we are. Watching MerDer in the last episode-wow- I just..have no words. Don't wanna give any spoilers to anyone who hasn't watched it yet but..wow. 6 years later and they still have that chemistry; 6 years later and they still make me swoon.

Anyway, the episode compelled me to write and the result is this. This is going to be a much less angsty story(i hope so) than my other one.

A lot of things will get clearer as we go on but one thing i'd like to mention is that in this fic I will be following the ages mentioned in the pilot.

That is, accordingto the pilot Meredith was 32/33 and Derek was 37/38 my point being that there was only a five-year difference between them.( I need that to make this fic work)

In this fic, Meredith is 31 and Derek is 36 and yes, they're both in their 5th year of residency and yes, it's complicated.

Like I said things will start to make sense as we go on. This is one part of the update and i'll soon post the second part too.

And on a side note: I'm not abandoning my other story( I will finish it even if it kills me)

So I'm gonna stop rambling now. Hope you guys stick around and please tell me what you think of this. :)