A/N Hi everyone! This is the first fic I've written in a long while so please go easy on me. I have also uploaded this to AO3 for those that prefer that platform - same fic name and same username. Anyway, I started writing this because I was bored in lockdown and also because I'm a sucker for a med school AU, especially a slow-burn enemies-to-lovers type one, so if that's your kind of thing please enjoy (if there are even any readers around for this fandom anymore lol). I want to make it clear that this is gonna be Slow Burn so be prepared! Also I intend to upload roughly once a week :)

I should clarify that none of these characters are mine, they all belong to Shonda Rhimes, I'm just borrowing them and making them do what I want for the sake of my fic. Also I don't study medicine (although I am a biologist), and I'm not from the US, so I've taken a lot of liberties with the way that their degree is structured - just a heads up.

Enjoy!

Chapter 1

"Slow down Cristina, you're going to make yourself sick", Callie grimaced, watching as her flatmate shovelled forkful after forkful of her dinner into her mouth. It was a sight to watch; her cheeks were bulging and there were strands of spaghetti hanging from her lips, red sauce smeared across her chin. Honestly, it was quite disgusting, but Callie supposed at least it meant she was enjoying it.

"Bu- its so fuc-ng -ood," Cristina mumbled through her mouthful, sending sauce spattering across the tablecloth. Callie frowned at the sight, before noticing that her flatmate was already scooping more food onto her fork and bringing it to her mouth, even though her lips were currently bulging from her previous mouthful.

Acting quickly, Callie reached across the table and snatched the utensil from the woman's grasp and holding it out of her reach, shooting an unimpressed glare in her direction.

"I'm serious, there is no point in me cooking for you if you're going to vomit it up ten minutes later," the brunette scolded. "I don't want to wake up in the morning and found you finished my cereal again because you got hungry." Callie was regretfully speaking from experience. This is why she usually tested her cooking out on Addison or Mark, as they usually had actual constructive things to say, rather than inhaling the entire plate in 30 seconds flat and following it with "yeah that was nice". Unfortunately, they were both busy tonight, and Callie wanted to get this recipe perfected today, so she'd made the decision that Cristina would have to make do as her replacement taste-tester.

Not that she knew she was being used as a guinea pig. Neither did the others for that matter. Well, they knew that they were helping Callie perfect her recipes, but they didn't know why. Not that they'd ever actually pressed the subject. She supposed they just assumed she was really passionate about making sure her family recipes were regularly updated. Which was half true. She didn't think they'd care about the real reason, but she liked having that as her own little side-project. Besides, they were getting free food out of it, so it's hardly like she received any complaints.

In front of her, Cristina made a point of swallowing her mouthful, wiping the remaining sauce from her cheeks. She took a sip of the wine she'd bought in exchange for dinner, and then pointedly stared at Callie.

"Well? Are you going to give me my fork back?" she said after a pause, the brunette still holding the utensil just out of her reach.

"Are you going to eat like a normal person?" Callie countered, raising an eyebrow. As much as she was flattered Cristina was enjoying the meal so much, it really was counterproductive if she swallowed it so fast she didn't get the chance to actually taste it.

"Fine, mom," she sighed, holding her hand out as Callie reluctantly passed the fork back, watching as her flatmate made a point of placing the food in her mouth very delicately, plastering a thoughtful look across her face whilst she chewed slowly. She swallowed her mouthful and brought her finger to the corner of her lips and gazed off into the room, as if deep in thought. "Hmm, the pasta is slightly al dente, which, paired with the sweetness of the sauce creates a taste sensa- ow!"

Cristina rubbed the arm that Callie had just swatted. "I'm just trying to give you my expert opinions! Isn't that what you wanted?" she frowned. "No need to hit me."

"Forget it," Callie sighed. She knew that Cristina only had one thing on her mind when it came to dinner time, and that was that it was food, and it was free. There wasn't really much point in trying to get any constructive help out of her. "I'm pretty sure I've got this right now anyway."

"It's really good Cal. Everything you make is always really good," Cristina conceded, taking another large forkful and shovelling it into her mouth. Callie sighed again. She really was a useless critic.

She took a small bite of her own meal, humming slightly in approval. She had perfected the sauce this time around, she was sure of it. Last time she hadn't added enough salt, which left it slightly bland. This time around the flavour was much better. This sauce was the one.

Scribbling a couple of notes in the corner of her recipe, she closed the book and tucked into her dinner, a sense of satisfaction washing over her. It really was good. It was for this reason that she even began cooking – she didn't see the point in eating shitty food when she could make something like this and enjoy doing so. It was a win-win.

Cristina had finished her entire meal within minutes, dumping her plate in the sink and excusing herself, citing an unfinished reading she had to get done before class tomorrow.

She was kind of a terrible flatmate, constantly making a mess and not bothering to tidy up, electing to spend most of her spare time in her room. But they'd been living together for nearly 4 years now, having moved in together in their third year of their undergrad at Georgetown and then deciding to look for a place together when they both got into Harvard Med. And whilst she was a mess, the Latina had grown used to her company. She sort-of liked the fact that they each had their own space and there was no expectation to be sociable all the time. Although, when Callie felt like it, Cristina was always down for lounging on the sofa with a bottle of tequila whilst they watched some low-budget horror film, even if they didn't talk that much.

Callie glanced at the clock on the wall. It was later than she'd realised, and she still had a chapter of her textbook to get through before her 8 am class the following morning. She sighed. She had hoped to write up this recipe tonight, but she definitely wasn't going to have time if she wanted to be even semi-awake the next day. Callie didn't do mornings on a good day, and all the coffees in the world weren't going to keep her awake through her lecture if she didn't at least try to get some sleep.

She quickly did the dishes, leaving the saucepan to soak, before scooping up her recipe book and the remainder of her glass of wine and heading towards her room to get going on her reading. However, as she crossed the threshold of her bedroom, she realised getting her work done wasn't going to be as straight-forward as she'd hoped.

"You're fucking kidding me," she groaned, dropping her head into her free hand.

Unfortunately for Callie and her plans for the evening, she had possibly the most unsociable person in the entire world living in the room above her. She'd moved in the year previously, and since then Callie hadn't known peace.

Tonight, it was a loud, repetitive banging accompanied by an overly irritating pop song filtering through the into Callie's room. She could feel the ceiling shaking under the pressure of whatever activity was occurring in the space above her. She assumed it was some kind of workout, based on the way that the rhythm of the banging matched the grating vocals of whichever peppy chart-topper was coming from the speaker.

God, she really hated that woman. Who the fuck decided it would be a fun idea to do a workout at 10 pm? Callie was certain the rest of the building would be kept up by her night-time activities.

This wasn't an irregular occurrence, much to Callie's frustration. From the first day that the duo in the flat above had moved in, they had been nothing but a total pain. If it wasn't sporadic exercise at the most inconvenient of times, it was parties with music so loud she could actually feel the baseline or hour-long phone conversations accompanied by irritating giggling. Occasionally Callie had found herself awoken by the sound of obnoxiously loud sex, which was probably the worst wake-up that she'd ever had the displeasure of experiencing. Luckily that one wasn't too regular, or Callie was certain she'd have had to start hunting for a new place to live.

To be fair to the occupant of the room above, Callie gave as good as she got. She liked to play her music out loud whilst she worked, and fine, maybe after the first few times that her day had been rudely interrupted by her upstairs neighbour, she had started to crank the volume up higher than was really necessary, just to give the woman a taste of her own medicine. And maybe she was a little less than considerate of those around her when she watched horror films late at night. She liked to imagine the upstairs occupant squirming in her bed as she was forced to listen to loud bangs and piercing screams.

It had become something of a competition between the two – who could irritate the other the most by being as obnoxiously loud as possible. It had come to a head on several occasions, with one of them storming up or down the stairs to bang on the other's front door, yelling that if they didn't stop making such a racket, they'd call security, or make sure they got no sleep that night, or yank their pretty blonde hair out of their damn head. Callie knew it was petty and kind of ridiculous, but it wasn't like she started it.

It was for that reason that she found herself immediately turning on her music, selecting a loud song with heavy guitars, jacking the volume up as high as it would go. If the ridiculous woman above wanted to keep her awake, she'd make sure to let her know that she wasn't going to roll over and take it.

She found herself smirking as she heard the banging cease for a couple of second, practically able to imagine her contemplating whether it was worth retaliating or not. Could see the cogs turning in her head as she thought through her plan of action.

Annoyingly, that plan involved turning her own irritating pop music up even higher and resuming her workout. God, she swore they wrote those songs to be as catchy and annoying as humanly possible. Now Callie was hearing two very different songs playing at the same time, which was rapidly starting to give her a headache. There was no way she was going to get any work done in this state.

"Callie, I swear to god you'd better turn that down!" Cristina yelled from the other side of the door, banging hard on the wood. "I know you and blondie have your stupid pissing contest going on but some of us actually like the sound of silence you know?"

Callie sighed, turning the volume down lower, knowing she was conceding but also aware that it wasn't worth pissing off her flatmate. She could be a real bitch when she wanted to be, and the brunette didn't really feel like having to head outside to reclaim her underwear because Cristina had thrown it out of the window again. That had happened more than once, and Callie had learned her lesson.

The pop music continued to filter into the room, louder since the Latina had retaliated. Groaning, she fished around in her drawer for her earphones. She really needed to finish this chapter. If the noise was still going once she'd finished, well, then she'd consider heading upstairs and throwing some untasteful choice words at the blonde bitch.

Callie had learnt the identity of the duo in the flat above pretty early on. In fact, it was the same day that they'd moved in that she had first found herself banging on their front door. The loud pop music had been playing for hours, and the Latina could feel herself getting progressively loopier as the minutes wore on. Then the music had switched to Disney classics, and Callie had snapped. It was at that point she had stormed upstairs, ready to give the new residents of the building a piece of her mind.

The person that had answered the door was vaguely familiar. And even worse, she was really, stupidly hot.

"Hi!" the blonde smiled. Her blue eyes sparkled in the dim light of the corridor, and a set of dimples appeared on her cheeks. She was wearing a tight pink strappy top that left her milky white chest exposed, a spattering of freckles covering her shoulders. She looked like exactly the kind of person that would be listening to Disney music by choice, and whilst this kind of person was the exact opposite of Callie's type, the brunette couldn't deny that she was stunning. Breathtakingly stunning. Heart-stop-in-your-chest-for-a-moment type stunning. Which incidentally was exactly what Callie's heart was up to right now. "Callie, right?"

"Uh, yeah?" the brunette responded, focus snapping back to the present situation, hoping that she hadn't been caught ogling the blonde. She wasn't quite sure how this girl knew her name, but the more she stared at her, the more she became sure that she had seen her before.

"We had anatomy class together last semester. You always sat at the back with that tall guy and the redhead," the girl continued, answering her unspoken question. It still didn't clarify anything for the brunette, however – she couldn't picture this stunning woman in her class. She was certain she'd have noticed someone that looked like she did.

The fact that she obviously knew Callie, yet Callie was still at a loss as to who she was was becoming increasingly embarrassing as the seconds wore on. The Latina could feel her cheeks begin to heat up as she tried harder to wrack her brains for some kind of realisation.

"I'm Arizona. Robbins," the blonde – Arizona, smiled, the dimples appearing again. God, they were cute. Since when had Callie been into cute?

Then it hit her. Arizona! Right! The peppy blonde girl that always sat at the front and got all the answers right. Callie had only ever seen her from a distance, which explained why she'd never properly paid her any attention, and she remembered finding her voice kind of irritating. She always sounded oh so excited to be there, even though the class was at 8 am on the furthest side of campus. Callie was certain that no one should be that perky first thing in the morning.

"Oh right, yeah I remember," Callie said, smiling back. She had come up here to give her a piece of her mind, however now she'd started to talk to her she was having second thoughts. Maybe they could be amicable. After all, they were both studying medicine, and she seemed nice enough, Callie guessed. A bit irritating though. And the fact that she was beautiful definitely wasn't relevant. Not at all. "Uh, I live in the flat downstairs," she started, trying to decide the best way to play this.

"Ah awesome!" Arizona responded, her voice so bubbly it practically bounced.

Awesome? Callie winced, revaluating the thoughts she'd just been having. This girl could try a little harder to be less annoying.

"Alex and I just moved in today! Alex Karev, the way. Also in anatomy last semester," Arizona went on to clarify. "Our old place was a dump, so we decided to find somewhere else before the new semester started. Super cool that there's a familiar face here!"

Alex Karev was a bit of a douche. That's all Callie knew of him. She'd never actually spoken to him, but she recalled Addison was stuck with him for a lab one-time last year, and she distinctly remembered the words 'self-centred ass' coming from her mouth on more than one occasion. Why someone moody like Alex was friends with someone as perky as Arizona escaped Callie, but what did she know. Maybe they were dating?

No, that image didn't sit right. Callie could barely picture the two sat next to each other, let alone in a relationship. Alex always looked so brooding and miserable, and the girl standing in front of her was like a walking kid's movie. Or maybe an advert for Adderall.

"Cool," the brunette replied, unsure of what to say in response. "Uh, I just came up to ask if you could maybe turn your music down a little? The walls are quite thin, and I don't really want A Whole New World going around my head for the rest of the week."

"You not a fan of Disney?" Arizona asked, tilting her head slightly.

"God no." The words came out a bit harsher than Callie had meant them to. The smile fell from Arizona's face. "I just meant, it's not my preferred genre." She mentally slapped herself on the forehead.

"Would you like me to play something different?" Something in her tone had shifted, and Callie watched as the blonde's eyes raked slowly down her body and back up to her face. Her gaze was intense, sizing Callie up, and the Latina could feel her heart rate increase slightly. "Maybe something more moody and edgy?" She raised her eyebrows.

"Uh, I'm not moody. Or edgy," Callie replied, mildly insulted at Arizona's assessment of her. Granted she was wearing an old Led Zeppelin t-shirt, but that was for comfort, not style. It was past 9 pm. "But sure whatever. Anything is better than Under the Sea."

"You seem to know a lot of Disney song titles for someone that is so against them," the blonde stated, smirking. There was definitely something present in the way her eyes twinkled that wasn't there moments before.

"Uh, they're super repetitive. The title of the song is always mentioned at least ten times. It's not hard to guess when you've been listening to them all afternoon. Which I have. Because the ceiling is thin," Callie countered, crossing her arms over her chest.

Before the blonde could open her mouth to reply, a voice came from within the flat. "Who is it?"

Alex, she assumed.

"Callie Torres!" Arizona tilted her head to the side and yelled into the space. "Remember her from anatomy?"

"Oh yeah, the hot one that's friends with that irritating redhead I had labs with?"

Callie frowned. So her assessment of Alex had been correct, he was a douche.

"That's the one," Arizona replied, making direct eye contact with the Latina as she spoke, a slight smirk playing on her lips. Callie wasn't sure if the blonde was implying that she agreed with Alex's comment about her being hot, but the thought that she might be made her heart beat slightly faster.

"Tell her that her friend was annoying," Alex yelled.

Ok, Callie really didn't like this guy.

"She didn't exactly have nice things to say about you either!" the brunette shouted back.

Arizona giggled, her dimples on full display. God, when had Callie ever found giggling attractive before? Who was this woman?

"I'm sorry about Alex," Arizona said, the smile from earlier having returned to her face. "He is yet to perfect the art of being a decent human being."

"Yeah, I can see that," Callie muttered. She could still hear the Disney music floating from the open door behind the blonde, and it was starting to grate a nerve. Why someone like Alex would be comfortable listening to that shit escaped Callie. But what did she know, he seemed like a weird guy.

"I'll turn it down. Sorry for disturbing you," Arizona said, her voice sounding genuine.

"Thanks," Callie replied, smiling in return.

Sweet relief.

"It's nice to meet you properly," the blonde grinned. She really was pretty. Callie was certain that she'd never seen eyes so blue in her life. "Guess I'll see you around."

"Yeah. See you," Callie responded, as the door in front of her closed.

Well, that could have been a lot worse she supposed.

To be fair to the blonde, she had turned the music down. And for a short while, there wasn't too much noise.

Unfortunately for Callie, it didn't last.

The following weekend they had thrown a party. And if Callie thought the Disney music was bad, then she was in for a very unpleasant surprise. All evening there had been a constant, hideous mixture of billboard top 100 chart music interspersed with trashy pop hits, a bit of hip-hop thrown in. And not good hip-hop, the kind of hip-hop that gave hip-hop a bad name. Callie recalled Cristina storming into her room and demanding to know who the trashy teenagers that had moved in above them were, and how many formal complaints it would take to get them out of the building. As the night wore on, Callie, who had been on her last nerve anyway, found herself totally losing her cool, finally breaking and storming upstairs to give the duo a piece of her mind.

"Callie! What are you doing here!" Arizona was definitely drunk. And she was wearing a really short blue dress that showed off the entirety of her long, long legs. That was also very low cut, giving Callie a wonderful view of her cleavage.

She looked incredible. If it were under any other circumstances, the brunette would probably have started babbling like an idiot, maybe trying to flirt a little before inevitably making a fool of herself. But right now, she was pissed off and ready to yell.

The apartment was practically bursting with people, red solo cups thrown everywhere, flashing coloured lights adding to the chaos that of the scene. It was manic, and Callie couldn't quite believe that no one else in the building had tried to shut the party down yet.

"I came to ask you why the fuck you're making so much noise at 1 am!" Callie yelled over the music, her face set into a scowl.

Arizona paused for a moment, a look of confusion crossing her delicate features. "Uh, it's a party, duh?" she shrugged, as if that made it totally ok.

"Do you realise how loud you're being? There are other people in this building, and some of us are trying to sleep!"

"It's a Friday night! Don't be a party pooper!" Arizona was grinning like a drunken idiot, leaning heavily against the doorframe. She somehow managed to achieve hot and cute at the same time, a strand of her straightened blonde hair having fallen from its place behind her ear, now brushing against her cheek, slightly to the left of one of her dimples. The way her bright blue eyes were focused on Callie was making the brunette start to lose her cool, the anger subsiding just a little, replaced by a flurry of butterflies taking residence in her stomach.

Then, just as she finished her sentence, an attractive brunette appeared behind the blonde, placing a hand on her waist as she whispered something in her ear. Whatever it was caused Arizona to giggle, sending a weird flair of jealousy flooding through Callie's system. She knew she had literally no right to be jealous, she had met this woman on a grand total of two occasions, but regardless the emotion added to the bubbling anger, and the rage she felt from before Arizona had given her that intense look came back in spades.

The brunette looked up at Callie, eyeing her up and giving her a disapproving glare, before disappearing back into the crowd.

That was the final straw.

"I'm not being a party pooper, you're being an inconsiderate ass!" she yelled at the blonde, watching as the smile quickly fell from Arizona's face. "Turn your trashy music off, it's giving me a headache!"

"Wow. I'm truly sorry ma'am, I didn't realise you were the VIP resident in this building," Arizona replied, sarcasm dripping from her voice, clearly now pissed herself.

"You'd better wrap this up soon or I swear to god, I'll…"

"You'll what? Call security on me?" The blonde was tilting her head in challenge, a look of pure rage across her features, which Callie could only assume was the mirror image of her own expression. "Oh boo hoo I'm so scared"

She didn't know how to reply to that. She had considered calling security, but it was a student block, so she doubted they'd do anything about it.

"Just… think about someone else for once! And get a better taste in music for fucks sake!" She yelled, knowing it was a shit comeback, frustrated that she couldn't physically force the woman to shut the party down.

"Whatever," Arizona muttered, slamming the door in the brunette's face.

That was it. If she insisted on being that piece of shit neighbour, well, Callie could play that game too.

The music had not stopped any time soon. In fact, it was almost 3 am when the noise finally began to subside, and there was still at least another hour of banging noises and people yelling as they made their way out of the building. By the time Callie finally got to sleep it was gone 4:30, and she was well and truly pissed off.

That night had marked the beginning of the feud between the two med students.

The following evening Callie had decided to have a horror movie marathon in her bedroom, attaching her laptop to her speaker and playing the 1978 classic Halloween as loud as possible, smiling to herself each time Laurie let out a piercing scream, imagining the blonde grimacing. She seemed like the kind of person that hated horror films, based on the whole Disney thing.

That had clearly struck a nerve with Arizona, as the following morning at 8 am the brunette found herself awoken by 'A Whole New World'. On repeat. For two hours. About an hour in, Cristina had started banging on her door asking what she'd done to piss off the genie from Aladdin. At around 10 am she had heard some not-so-quiet yelling coming from above her, followed by the music being shut off and nothing but the sound of blissful silence. She could only assume Alex had had enough of Arizona's petty comeback, Callie being able to make out the odd phrase like 'acting like a deranged infant' and 'living in a fucking princess castle'. The brunette had found herself snorting, but she was definitely the loser in this situation. The song remained stuck in her head for a good two weeks.

It had continued like this, on and off, for over a year now, and neither party was showing any signs of giving in any time soon. At first, they had had several face-to-face encounters, banging on the other's front door and yelling choice words about the other's terrible music taste, perverted film choices, or obnoxious exercise habits, but they had become less frequent when they had realised that neither of them were planning on giving in. They were both stubborn as hell and adamant that they were going to win this stupid, endless fight, much to the dismay of their subsequent flatmates.

So, now Callie was sat on at her desk, earplugs in, volume up, trying to drown out the sounds coming from upstairs. She tried to focus on the page in front of her, but she found herself re-reading the same line over and over, taking nothing in.

After ten minutes of trying and failing to concentrate, the brunette decided to have a break, pushing the textbook to the side and opening her laptop. She immediately clicked on her browser and headed straight to a familiar page.

Cooking was one of Callie's favourite hobbies. This wasn't a secret, anyone that knew her knew she loved to be in the kitchen. What they didn't know, however, is that Callie did more than just cook. At some point in her first year of med school, after being unable to find a suitable recipe online for chicken piccata, she decided to make her own, based on a family recipe. And she was so happy with how it had turned out, she decided she may as well share it, so other people could enjoy it too. So, she had set up an anonymous blog, and posted it online.

And this had received a lot of positive feedback, way more than she had ever expected. So, she posted another. Which was equally well received. So, she did it again. And again. Eventually, she decided to put a name to this blog – 'A Student and their Kitchen'. A page that posted recipes for quality meals on a budget.

It had now been over two years of running this blog, and it had become quite popular amongst students. The page was still anonymous – no one knew that she ran it, not even her friends. She felt it was kind of a stupid hobby and figured if anyone else found out about it they'd judge her for wasting her time. She couldn't really name exactly what had driven her to start it in the first place, but she had come to find herself really enjoying creating these recipes and sharing them with the world. It was like her own personal cookbook. That she also shared with the entire internet.

Right now, Callie was tired. And the noise coming from upstairs was getting on her nerves more than she liked to admit. Plus, she really couldn't be bothered to read about infectious diseases and microbiology. So instead, she decided to start writing up the recipe she'd just finished. Work could wait.