Author's Note: I feel like I should add – there will eventually be certain chapters and sections (primarily flashbacks) in the future that will be more Mark-centric. Also JK on this only being about 10 chapters. It'll be a lot more, because I'm terrible at outlining.

Chapter title is from the song "Smell" by Sleeping At Last.

. .

. .

Chapter 3. Gravity in an Hourglass

Addison and Mark are equal parts amused and disgusted with themselves when they talk about the fact that if they were still in their twenties, their Friday night would have just been getting started at this hour. Instead, they have almost reached the end; they are tired and feel ready to go to sleep. Mark gets up to refill his water bottle, presumably a concluding task before he calls it a night, and while he does this, Addison stares out the sliding glass doors from her seat at the kitchen table. The sky is dazzlingly clear tonight. There aren't stars like this in the city. Hell, there basically aren't stars in the city, not with the persistent glow of light pollution. It is beautiful in the Hamptons year-round, but Addison prefers it in the fall, and not just because the summer-playground crowds have thinned. Between the stars pinned to the blue-black foundation of the sky, the vibrant clusters of sunburst-colored leaves quivering on branches, and the pristine nature of the coastal landscape – it is all just stunning. And it is mostly quiet, this time of year. October in Montauk feels like a well-kept secret, sometimes.

"When do you think Derek will get here?" Mark asks, leaning against the center island.

"Probably a little before noon, depending on what time he gets out of the city," Addison replies. Her hands are warm from the mug of tea they are currently molded around. The two glasses of wine that preceded the tea help with the warmth, too. And so did hearing from Derek, who confirmed he will be coming tomorrow as planned. "So…" she gives Mark a smile. "You're at least spared from having to go fishing tomorrow morning."

Mark makes a face at fishing – he hates it – but it is not the subject he elects to bring up. "You look sad," he says, and it doesn't surprise her. Mark has always been direct.

Addison's thoughts haven't changed, even though what Mark says warrants a response: discussing her marital woes with anyone outside her marriage is inappropriate. This isn't the same as complaining to Savvy about how Derek will ask where something is without bothering to look for it first, or venting to Naomi about the infamous Salmonella Thanksgiving from years ago. Those things were just things, and what is going on right now is a problem. Plus, Addison's marriage may be in irons, but Derek doesn't deserve all the blame. She is busy too, and she hasn't exactly tried to address the state of their relationship in a way that isn't passive-aggressive or just plain bitchy. She and Derek haven't discussed in earnest what is currently going on with them.

"I'll be okay," Addison replies, because it's the truth, and it feels important to acknowledge that first. She lowers her head for a moment, breathing in the earthy scent of her tea. "But yes…I am a bit sad. And invisible. And I shouldn't be either of those things because I talked to my husband and he's coming tomorrow, but sometimes I think I'm just…" she blinks up at Mark and tries to keep her voice steady. "Mark, you would…you would tell me if there was someone else, right? I know Derek is your best friend, but -"

"Yeah. I really would. But there's not anyone else. At least from what I can see, and I seriously can't imagine…do you really think he'd cheat?"

Addison shakes her head. Her father was – and still is, though she knows about it to a lesser extent now, thank God – a serial cheater. She knows the signs, doesn't she? And Bizzy, well. This time she internally shakes her head, because she doesn't want to think about that right now.

"No. I guess not," she admits. "You did tell him once though that monogamy isn't natural. Before the wedding, you informed him that God intended for you both to have many, many women. And…" her mouth furls into a smirk. "If those are in fact God's expectations, Mark, then congratulations: you have surpassed them."

"Derek told you about that?"

She giggles. "Oh, absolutely."

"Well…" Mark says. "Hopefully he also mentioned the part where I said 'Addison's great' or something to that effect."

"He did," she confirms. "And I didn't take it personally, for the record. I laughed when Derek told me. I know marriage isn't really your thing, at least not yet, and I'm not making it look too appealing at the moment. But – it's okay. Tomorrow will be better, and I promise to stop putting you in the middle of my relationship. And in the meantime, I can at least assure you that Tessa-down-the-street has no intention of being Mrs. Mark Sloan. Not legally, at least. That inevitable divorce is going to drag on for years."

"Probably not as long as the husband-wife-mistress boob job one I told you about last week. I'll keep that in mind though. Well…I'm gonna turn in, I think…" Mark says, tapping his hands twice against the marble countertop as some sort of gesture of conclusiveness. "Oh, but Addison?" His lips part in a small smile. "Just so you know…I see you."

"What?"

"You said you were invisible. And I'm just telling you that you're not. I see you. Lots of people see you."

"Thank you for saying that," she replies, voice soft and lilting. This touches her.

"Yeah." Mark shrugs a shoulder. "Anyway. Don't stay up too late."

The earnestness in this advice makes Addison laugh. "Thanks, Dad," she chirps with sarcasm.

"Hey." Mark gives her a look of fake annoyance. "We just had a very nice bonding moment. Don't ruin it by bringing up the Captain or Everett."

"Duly noted. Night, Mark."

"Good night, Red."

. .
. .

Four Months Earlier

"She's going to bring up the kid thing again," Addison mumbles, failing to keep the sullen edge out of her tone. She has the sudden urge to kick at the glove compartment. It's June, and humidity is already creeping around them as they make their way north. "It makes zero difference that it's Amy's day," she adds. "You know your mom will find a way to drop it in." She is positively dreading the mother-in-law and (to a less extent) sisters-in-law comments that will come up this afternoon at Amy's party. The youngest Shepherd has graduated from med school and is starting her residency at Johns Hopkins next month. Addison knows Amy would prefer to head off to Baltimore without any fuss, but Nancy and Liz pushed until Amy unenthusiastically agreed to a family-only party at her mother's house.

"No, she won't. Like you said, today is about Amy. Mostly we'll just all be holding our collective breath while waiting for Amy's bull in a China shop behavior to start…" Derek waits for a beat, but does not actually expect Addison to engage. She thinks Derek and his sisters are too tough on Amelia. "Anyway. I already told Mom not to ask. I said we're not ready yet."

Addison and Derek's wedding anniversary is coming up soon – their tenth. Ten years together and zero children. Three of Derek's sisters have essentially birthed litters, proving faithful to the Irish-Catholic background none of them really care about. There are seven nieces and four nephews. And Liz is pregnant again with twins. So of course Carolyn will find a way to bring it up. Addison is certain of this. A bull in a China shop. Fine. If they are talking in idioms, well, then sometimes butter wouldn't melt in Carolyn Shepherd's mouth.

"You said we're not ready or that I'm not ready?"

"Addison -"

"It doesn't matter," she interjects with a tired sigh. "I'll be the bad guy no matter what. Your mother hates me. She's hated me from the moment she met me and that's never changed."

"That's not true. My mother doesn't hate you, Addie. I seriously can't believe..." Derek shakes his head. "You really still think that? After all these years?"

Yes, because she does! Addison wants to scream. But what good would it do? "Sorry," she says instead. "I'm just being...it's okay. Let's talk about something else. Tell me about your most recent surgery." She knows that will brighten Derek's mood. She doesn't always mind that most of their conversations – the ones that are not tension-filled, at least – revolve around work. She loves Derek's passion for his job. Even as a student, he was hopeful, sincere. It was always a beautiful day for cadaver dissection and to learn about the stunning complexity of the human body up close. It was a beautiful day to become a surgeon. And now it is always a beautiful day to save lives.

The first Thanksgiving they spent together – they studied for exams and ate really bad Chinese food, because they were too busy and too tired to even think about cooking – was when Addison first realized how deep Derek's passion ran. She was complaining about neuroanatomy (the one class she truly, truly hated), while her boyfriend couldn't get enough of the subject. Derek talked about how unique the brain is, its enduring mysteries, how it is so unlike any other organ. It is responsible for movements, for words, for feelings, for thoughts, for who a person ultimately is – and how humbling and profound for a surgeon that a patient would be willing to trust a surgeon with all the things that make them them.

Surgeries. That's where it's at. Derek doesn't want to talk about his actual practice. Addison doesn't think her husband regrets going into private practice, but it definitely isn't everything he thought it would be. The political side of trade-offs for operating privileges at certain hospitals, the managerial aspects, the insurance and expenses and legal and facility things he has a hired team to handle for him but said team is still constantly in his ear – Derek isn't suited to any of that. Somedays, Addison thinks he would be happier being in the hospital full-time, even if that means once again being at the mercy of the churn and burn system.

"Addison…we're not getting any younger," Derek says gently. Talk of surgeries clearly is not going to distract him. "I mean. You're thirty-seven. And I'll be thirty-eight in September."

She knows what he's trying to say. She is long past her peak fertility, after all. There's the cringe-inducing term of advanced maternal age. She knows the exact chance of getting pregnant per cycle if they were to try right now, in a year, in three years. There still is time though. There's still time for her to naturally get pregnant.

She thinks of a line from a poem she recited in eighth grade: learn to labor and to wait.

"I don't want to wait forever," Derek adds.

"I'm not asking you to. But I'm not ready yet."

"But when will you be ready? Take the career out of it for a second. When will you be ready as a person?" He asks, and Addison clamps down on the inside of her cheek. If he starts talking about Bizzy, she might cry. It's been two years now. But still. So much of her past has been carried forward, and that makes parenthood a bit worrisome. "Do you feel like you're at least closer to wanting to try?"

"When will you be home enough to try?" Addison shoots back. "You're absent, Derek. All the time lately." And then she goes for the jugular, but in a way it's a question more geared towards attacking herself than it is him: "Do you even love me anymore?"

"Of course I do."

"Can you at least look at me when you say it?"

"God, Addison." Derek's hands tighten on the steering wheel as he shoots her a quick glance, expression withering. "I'm driving. Do you want me to kill us? Yes, I still love you. You didn't answer either of my questions, by the way."

"You didn't answer mine."

"I said that I loved you. You're my wife." He looks over again, holds her gaze a moment longer this time. "Of course I love you." The of course part makes her want to cringe.

"Before that. I asked when you'd be home enough to try."

"Because being at home to hear all your nagging and worrying about every little thing is so enjoyable," Derek snaps. Resounding quiet follows. "Addison…" he inhales slowly. He uncurls one set of fingers from the wheel, and holds a hand out to her. "I'm sorry. I didn't mean that. I just…I just really want to have a kid. Kids."

You meant it, Addison thinks. She is grateful that her Gucci frames hide the tears now glistening in her eyes. You just didn't mean to say it to out loud. And you want kids, or you want kids with me? Because there's a difference.

Addison slides her hand into his. "I do, too, honey," she says softly. It's true. "I'd like to…I'd like to revisit this conversation. But I think – next spring. Let's start trying next spring. Okay?" This feels safe. She wants to be a mother, probably more than anything, but she also wants to feel ready to be a mother. And maybe Derek will start drifting back to her, rather than away from her. Besides, what kind of mother would she be if she were ready for a child now, while her marriage lacks meaningful connection and her husband is just going through the motions? It would be selfish to bring a child into this situation. Of course. Of course Derek still loves her, but that response was cringe-inducing because it's autopilot, routine. It's just playing the role of dutiful husband. And somedays, that just isn't enough.

She thinks of nautical flags streaming from sailboats. Alfa/alpha. It means there is a diver down, so proceed with caution; otherwise, there could be a collision.

Derek grins widely at Addison's proposal, at this sign of a truce in the wind. "Yeah?"

"Yeah."

It pulls Addison back to their neuroanatomy textbooks all those years ago, the air sharp with the smell of uncapped highlighters and lukewarm egg rolls and all that dizzying lust for one another, their autonomic nervous systems at play even then.

She will be thirty-eight next spring. Some days though, she feels so much older than that.

. .
. .

Addison has to think about what happened to Bizzy in pieces. It's too overwhelming otherwise. Even now, but especially back when it happened, when she was strangled in the thick of it.

It has already been two years and it has only been two years.

Two years ago. It truly was one of the worst days of her life. The worst, really. What else could possibly compete with that afternoon?

"I think I'm…I think I'm traumatized." Addison's voice rises at the end, as though it's a question, as though she really wouldn't know the answer or be able to tell. She's a doctor; the care she provides to patients is trauma-informed.

"Of course you are." Derek tries to be still, to just hold her, to stop wiggling his left hip against the mattress. The bed in Addison's childhood bedroom isn't exactly uncomfortable, but it's not their mattress, so that in and of itself makes it uncomfortable. He doubts he'll sleep much tonight anyway, but it's not like his wife will either. "That was...look, the thing to remember though is that Bizzy is going to get help. I know it's not really the Forbes or Montgomery way to ask for help, but it can be done. And it can be done discreetly."

"I know. And I know...Derek, I know she's in pain, but just if...if Mark died...God forbid, of course, but I'm just thinking, like if it were Mark or Nai or Savvy or something...but if…if it were Mark, you wouldn't..." she trails off, knowing he can finish the thought from there. Her eyes are shiny with tears in the darkness, and her husband's eyes soon match hers.

"No, I wouldn't." Derek swallows heavily. "I'd be devastated though. You would be, too. But maybe it was different for your mom and Susan. I'm close with Mark – he's like a brother to me, you know that – but Bizzy and Susan were close too and maybe it's just...different? Not to be stereotypical, but maybe it's like…a sex thing?"

Addison knows he means it biologically speaking. But it still cuts her to the core.

"I think it's a lot different. A lot different in how they loved each other."

"What do you mean?" Derek asks. Kind, thoughtful Derek, who knows what it's like to try to save someone you love, who once breathed the life back into his hurricane of a youngest sister when she was legally dead for three minutes.

"I'm not sure," Addison replies woodenly. She can't talk about it. Not yet, at least. "They were just close, I guess."

(In retrospect, the stress of this time was so powerful that it shouldn't have surprised Addison when her period was late. And it shouldn't have surprised Derek that she had mixed feelings about the possibility of being pregnant.)

"Okay." Derek's lips sweep against the dip in her hairline. "Try to sleep a little. I'm here for you."

. .
. .

He's not here. And he's not coming.

A patient – Derek's patient, who he operated on last night – just had a seizure. And the follow-up scans don't look good. He needs to get the patient back into the OR. Addison gets it, even though her heart balloons with despondency and she just wants to scream. If the situation was reversed, of course she would have stayed to tend to her patient. This isn't the sort of thing she can issue an ultimatum over, if it were to come to that – and it definitely hasn't come to that. She doesn't want it to come to that, but something has to change. Derek would never walk away – not physically, anyway. There are days though, when Addison's loneliness and feelings of not being good enough seem to thread deep through her veins, that she thinks maybe she could do what Derek will not, even though the idea of ending up alone is terrifying.

It's a cold morning, and far too early to be up on a Saturday, but Addison can't bring herself to go back inside yet. She thinks about pulling her phone out of one of her pajama bottom pockets again. She should send Derek a text message at some point. She shouldn't have yelled (hence why she went outside, because she knew she was going to yell). And she definitely shouldn't have ended the call when Derek was mid-sentence.

Addison hears the rasp of the front door open, and the quiet shuffle of Mark's footsteps pushing against the porch steps that are behind her. She gets the sense – even without turning around to look at Mark – that he already knows. Perhaps Derek texted him.

"He's not coming," she says, voice cracking.

"I'm sorry, Red."

"It's okay. I'm okay." She shifts around to face him, dabbing her thumbs against the delicate, now-reddened skin under her lower eyelids.

Mark shakes his head. "You're not really okay though."

"No. But…I will be."

"Do you want me to leave you alone, or…do you want a hug? There's other options, too, if that's not what you want. Tons of them. We could get breakfast…go to the beach and you can yell at me for deciding to get in the water…we can start drinking…write the next Great American Novel…you can introduce me to Married Tessa…" Mark smiles and offers a small shrug, knowing he is closer to getting her to laugh. "I can keep going if none of those are appealing."

"No, it's okay…" Addison giggles. "Thank you, Mark. A hug sounds kind of nice."

There have been some hugs before. They hugged at her wedding reception. And at their med school graduation, there a combination of happy, celebratory hugs in their mutual circle of friends. There was definitely a hug or seven when Addison drank enough at her thirtieth birthday that everyone in a five-mile vicinity was getting hugged. And when they passed their boards. She hugged Mark when he told her and Derek that he was going to open his own practice, the first of the three of them to take that plunge. And she hugged him a few years ago when his mother died. Hugs really aren't standard for them though, and she finds herself thinking that that's a shame, really. The man gives good hugs.

"You're one of my best friends." Addison sighs gratefully while she breathes in the scent clinging to Mark's long-sleeved shirt. Something woodsy. Cedar, maybe. His head is dipped down, angled close to her cheek, and her words are light and breathy against the hollow of his throat.

"You're one of my best friends too, Addie."

"There's a really good breakfast spot over by Ditch Plains Beach," she adds. "We could drive there and then walk to the beach after and just hang there for a bit? It'll be chilly, but as long as we wear layers, it'll be fine. You can swim if you want, but I'm definitely going to yell at you first because it's way too cold."

"Too cold for you, maybe." Mark says with his trademark stubbornness.

Addison starts to pull away mid-laugh at the same time he goes to kiss her on the cheek. They are not well-practiced in their pre-hug and post-hug movements though, and Mark's lips land dangerously close to the corner of her mouth. She almost gasps.

"Shit. I'm sorry." Mark's cheeks instantly redden. He kissed her on the cheek mid-hug at her wedding reception. That one landed closer to her ear though, she thinks, or at least in an area that could be considered safe. Not like this. She could feel Mark's stubble scrape against her bottom lip and chin (in a nice way, though she shouldn't think that). "I didn't mean…I'm sorry."

Addison shakes her head quickly. "It's okay, Mark. I turned my head."

"This is what happens to me when I try to be nice, apparently. Let's, uh…" he laughs uncomfortably. "Let's maybe not mention this to Derek."

"No." She grins weakly. "I can't imagine he would be too happy. Our secret?"

"Our secret."

. .
. .

References:

Derek to Addison: "Remember med school? We spent Thanksgiving studying for exams and eating really bad Chinese food instead of turkey." (Grey's, 2x09)

Addison: "Do you love me? Do you?"
Derek: "Of course I love you."
Addison: "Can you say it without looking at the floor?" (Grey's, 8x13 – the AU episode)

Mark: "Addison's great, but one woman for the rest of your life? It's not what God intended. Especially for men who look like us. God intended for us many, many women, a staggering number of women." (Grey's, 9x01)

Addison: "This is the hot dog Thanksgiving all over again."
Derek: "What?"
Addison: "You know. Your mother breaks her wrist, so the day before Thanksgiving, you invite 34 people over to our house, without asking me, knowing I've never cooked a turkey in my life. Your sister [Nancy] gets salmonella, and your mother accuses me of trying to kill everyone. And then you, ha-ha, make hot dogs, and you're the hero." (PP, 2x16)

Derek: "It's a beautiful day to save lives." Every episode, amiright?

I hope you liked this! Reviews are always appreciated. :)