Author's note: This is my very first time writing a Grey's fanfic; I recently starting watching Grey's and Private Practice and couldn't help but ship Mark and Addison. I mean hello their chemistry is off the charts and even Shonda herself wanted them to be together in the end.

Few things to keep in mind-this is loosely based off Song Beneath the Song, although of course it's Addison in the car crash and not Callie. The flashbacks start towards the end of season 3, a little after Addison returns from LA, and then the story goes AU.

Chapter 1

You wait and you wait for the perfect moment to propose. Because let's face it, everyone wants the picture perfect proposal (if there even is such a thing) they can look back on (and let's be real, brag about) for years to come. But let's say you wait too long, because of course you want everything to be right, from the music to the flowers to above all the location…until you end up blurting it out at the most random time.

That was his first mistake.

In hindsight, he should've foreseen so many things. The slick conditions of the perpetually wet Seattle roads. The sheer number of travelers because it was freaking Memorial Day weekend. The way things had been going so beautifully and wonderfully marvelous for the past several months.

The mere idea of a simple weekend getaway before Carson's (gender unknown, as she'd wanted to wait until his/her birth to find out, the ultimate surprise, she'd called it) birth was nothing more than tempting fate, or rather laughing and spitting in its face because he had the audacity to believe that they'd finally get the blissfully happy ending they'd both craved for so long.

What an idiotic notion.

His head was throbbing, something wet, probably blood dripping down around his hairline. He could feel the rough nylon against his face, and for a second he almost wanted to remain buried, and could almost pretend it was just a pillow, albeit uncomfortable, and he'd open his eyes and find her curled into him, her red waves spilling out in haphazard directions, his hand wrapped around her rounded stomach. He slowly raised his head a couple inches, almost fully expecting to be back at home.

She wasn't in her seat.

He sat up quickly, a little too quickly, and for a second he swore he saw stars float before his eyes. He shut his eyes and rested the back of his head against the seat for a moment, taking slow, deep breaths. So she wasn't in her seat. Perhaps she'd already exited the car, taking out of her cell phone, yelling at whoever had the misfortune to be on the other end. Out of all his experiences, the most valuable lesson had to be to never cross Addison Montgomery when she needed something.

Yes, that was it. She had to be outside. He opened his eyes, and then saw it. A pair of feet, still clad in a pair of expensive heels. And that's when all hope that everything would ever be ok again slowly dissipated, replaced by cold dread.

Because he knew those shoes. Just that morning, they'd erupted into a huge argument about those damn shoes, with the fancy name he could never remember but could recognize after knowing her for years and finding her damn shoeboxes everywhere. Black, leather, with a wicked heel he hadn't wanted her to wear, but that she'd insisted on wearing because if anyone could rock a pair of heels it'd be her. He'd relented of course.

He pushed the button to unbuckle his seat belt, fumbling once, twice, three times before pulling the damn thing loose. The car door opened rather easily, and he stepped outside to find her curled up, lying on top of the car.

No.

"Addison!" His voice sounded low, rough, almost like a growl.

The calm, almost deafening silence of before was broken by soft whimpers, her chest rapidly rising and falling. Although her eyes were only half open, he could see the pain and panic in them, and the desperation and fear that chilled him to the core.

One of her arms lay at an awkward angle, and the word broken came immediately to mind. The blood soaking his hairline was laughable compared to the red pool rapidly growing beneath her. Yet that was nothing compared to the internal damage he could only begin to imagine.

Her hand shakingly lifted up, perhaps working its way down to her stomach, as her eyes darted around rapidly. "M…M…"

He took her good hand immediately, stroking her hair, warm sticky blood mingling with the red of her hair. "Shh. It's all right."

She started to gasp loudly and fearfully, clearly distressed and shocked, as comprehension of what happened settled in.

"Hey, look at me. I'm here." He said with tenderness he never imagined he possessed. "You're going to be okay. I promise you. We're going to be ok."

Was she, though?

Without taking his eyes off her, he managed to take out his miraculously undamaged phone with one hand, mumbling almost incoherently, barely able to communicate their location, her status, and that they needed help now, not thirty minutes from now, but now, because she was going into shock and he needed help now.He could dimly hear the driver of the truck speaking into his phone as well, likely to a different 911 operator.

Her eyes started to slide closed. "No!" He roared, dropping the phone, the operator on the other end immediately forgotten. He tapped her face with one hand, the other one still encasing hers. "Stay with me."

How many times had he thought those very words? The many nights she'd crept out of his apartment to back to her (now ex) husband. The night she'd informed him in a detached tone that she was going to Seattle. The morning she left him still in the hotel bed, telling him he'd been nothing but a booty call.

"Stay with me." He repeated. "Addison." Mark Sloan did not beg, yet when it came to her, all senses and logic were lost.

But like so many other times where she listened to no one other than herself, her eyes fully slid shut and did not open again.

The paramedics arriving were a blur. The ambulance ride, chaotic and full of shouting, was a blur. All he could remember was desperately clinging to her hand, responding angrily that he was a doctor and would under no circumstances leave her side whenever anyone tried to say otherwise.

Somehow, they arrived at a place Mark had started to think of his as his, no as their second home (especially since that was likely where they'd conceived Carson). Seattle Grace Mercy West.

They were pulling the gurney where she lay out, and he stumbled forward almost blindly. And suddenly dozens of blue scrub clad figures were rushing forward to meet them.

"Hey!" A voice shouted beside him, but he was focused on nothing but Addison, staying with her as he'd once silently promised he'd do back in med school when she'd pout-begged him to not leave her to cram alone in the library. "We got her. She's in good hands. You need to stay back. And get that checked out," she said, nodding at the cut on his head.

Bailey. This caused Mark to pause for a second, long enough for the gurney to be rushed out of view and into one of the trauma rooms, completely surrounded by the other attendings shouting instructions and directions at each other. Interns stood by and gawked, completely horrified at seeing that instead of a nameless, faceless patient, it was in fact one of their mentors lying on that gurney.

"No!" He protested, pushing against the arm she'd thrust out to block him. "I-I need to be in there!"

Miranda Bailey was not one to be pushed around. She was not called the Nazi for nothing; hell some of the other attendings were often intimidated by her, and yet seeing his anguished expression caused hers to soften in a way that was rarely seen. "Alright. But you need to stay back." She repeated. "I mean it."

Like he could be operating on her with the way his hands had started and would likely never stop violently shaking in a way he couldn't control. He could only bring himself to nod curtly as he followed Bailey.

Inside, the attendings rushed around, throwing around words and phrases he'd known so well for nearly 20 years, yet as he stood dumbly at the back of the room watching them monitor this and that, yelling out things like "pressure's dropping" or "O2 sats" they sounded foreign and strange. Part of him wanted to jump in, his brain automatically categorizing what to do first and what could wait, but one look at her face and that achingly familiar hair, and his knees buckled so that he had to lean against the wall for support.

His eyes fell onto her swollen stomach. Oh God. The baby. What if-

"C-can you check…" his voice sounded choked and hesitant, getting exactly no one's attention. He curled his fingers into his palms and tried again. "Check for a fetal heartbeat, damnit!" This time, he sounded a lot more confident than he certainly felt. Everyone paused for a moment, and then he heard Richard telling everyone to step back while Lucy Fields, who was slated to be Addison's replacement during her maternity leave, instructed them to keep quiet.

Maybe it was only a few moments later, he couldn't really tell, but a telltale sound suddenly filled the room. Mark nearly collapsed against the wall, and he could see that weary relief was visible on everyone else's faces. For right now, at least, all hope was not lost. Their little miracle, one both he and Addison had wanted for so long, was still alive.

But the moment was not long lasting, because seconds later the room filled with a different kind of sound, this one indicating impending death instead of life. Mark watched with a sort of morbid fascination as her body gracefully arched up with electricity once, twice, three times, and a tube was shoved down her throat. How was it that a few simple instruments could mean the difference between her coming back to life or being forever lost to him? How could everything be taken away with such a simple moment?

"Charging to 200." Owen said, his jaw set with concentration. He readied the paddles, and the other surgeons backed away. Her body lifted up and down quickly, yet monitor still indicated a flat line with a question mark.

"Come on, Addison." Bailey murmured. Mark was suddenly reminded of the way she'd once mentioned that there weren't too many people she could stand, but Addison was definitely among those she actually liked.

The paddles were charged again and again, to no avail. Owen looked helplessly at the monitor and back down at Addison's almost serene face. At this point they normally would've given up, if it was a regular patient.

If it was a regular patient, that is. But this wasn't.

"Sloan, maybe-" Owen began.

It wasn't Mark who spoke up. His voice was lost, gone. Instead, it was Derek. He always did know how to read Mark's mind, to a certain extent. "Absolutely not. She wouldn't give up on us, and we're not doing this for her. Again."

As Derek spoke, his face full of emotion, Mark was reminded of the fact that his best friend had once possessed deep feelings for her, something that had caused no small amount of jealousy, hate and rage to build up inside him. He'd never appreciated her as much as Mark did, and he still trumped Mark when it came to the length of time he'd had to call her his wife. 11 freaking years. But over time, as he and Addison got together for real, those feelings smoothed out, and they'd become Derek and Mark and Addison again as they once were in med school and for a long time after.

Owen acquiesced, and readied the paddles again and again. Mark stuffed his fist against his mouth. No, you can't do this. Come on, Addie. Please. I can't lose both of you. Not like this.

By some miracle, the beeping dissipated, her heart rate skyrocketing back to a normal-ish range, and the gurney was wheeled out towards the elevator, still surrounded by Derek, Meredith, Callie, Arizona, April, Jackson, Owen, Cristina, Richard, Bailey, and…it was almost laughable that the hospital's best surgeons were busy attending to one patient while there were so many more that needed saving.

But she would never be just a patient. Not to him, and not to any of them.

He almost wanted to tell them to go and help someone else, because this might be a futile-no. If nobody was thinking that, why in the hell was he?

What the hell was wrong with him?

He attempted to follow the gurney-after all, he was one of the best surgeons Seattle had to offer and damnit this was Addison and he swore she'd never be alone anymore and right now despite being surrounded by so many she might end up irrevocably and forever alone, but a short, squat shape blocked his path.

This time, Bailey shook her head firmly. "No, nuh-uh. You're not going anywhere near that OR. Not inside and certainly not in the gallery. I don't care who you are or who she is. You will go get that head of yours checked out and grab a coffee, take a nap or quite frankly stay the hell away while we do our jobs." She then turned to the side. "Hey! Come here! Yes, you fools, I mean you!"

Two visibly trembling interns shuffled over, unable to look him in the eye. He recognized the shorter one as one who'd worked with Addison just the morning before.

"You two are in charge of keeping Dr. Sloan away from the OR, you hear me? I don't want to see his ass or either one of yours until I page you."

"What gives you the right-"

"I'll tell you what gives me the right. This is Addison we're talking about. I know what she means to you, to all of us, and if you know what's good for her and you you'll listen to me."

"She's my best friend! My family! She's all I have!" As he spoke these words he knew they weren't quite true. The blue scrubbed figures riding up in the elevator with her, Derek, Meredith, Richard-they were all his family. But not in the same way she was.

"She doesn't need you dying." Again, Bailey's expression softened as she spoke, and he could sort of see how she also earned the reputation of being caring, albeit in an aggressive way. "Not on my watch." Despite her shorter stature, Bailey impressively managed to intimidate him, sort of. She walked rapidly away, shooting a glare at the interns. "Now get lost."

Get lost. How ironic. Without her by his side or a simple page or phone call away, he already felt lost in more ways than he could imagine.

Author's note: So what did you think? Please leave a review!