A/N (09/06/15): Hello friends! As hard as it is to believe, it's been about two and a half years since I last updated one of my stories. My sincere apologies to all of my loyal readers for essentially dropping off the face of the earth, and thank you to everyone who kept reading, reviewing, and messaging me while I was lost in "real life", whatever that is!

I am working my way through this story, tweaking it slightly to take it in a direction that will better bring it to the conclusion I always intended it to reach. I'll be posting the updated versions of the existing chapters in batches until it's all caught up and we get back into new material. Most of the changes are minor in the first 15 or so chapters, but there are a few slightly more substantial changes in the later chapters of this new version. So even if you've read the story before, I encourage you to start at the beginning and work your way forward - I'll date all the updated chapters as they go up, so that it is clear what has been updated. Thank you all for your patience!

Mark glanced at the clock as he crumpled his worn shirt and tossed it into his duffle bag. Taking one final look around the room to make certain he hadn't left anything, he zipped the bag closed and slung it over his shoulder. He liked to think that under normal circumstances – whatever those might be – he would have taken more care with his packing, but as it was, he was more concerned with making it out the door and to the airport in time to catch his flight home.

He'd barely managed to sleep a wink all night, tossing and turning as his mind tried to sort through the tumultuous events of the previous day. When he had finally managed to fall asleep, he'd been so exhausted he had slept straight through his alarm. At this point, he figured he'd need to find the craziest cabbie in all of New York City if he had any hope of making it to the airport before his flight left without him.

"Ah, Dr. Sloan, good morning, sir," the doorman said as Mark stepped off the elevator and into the small lobby of the boutique hotel Lexie had booked him into. He supposed she found some peace of mind in knowing he'd be in a small place where the staff knew his name – not that he had ever given her any reason to worry, but his reputation had preceded him in their relationship, and he knew she sometimes had difficulty reconciling it with the man she'd married.

"I need a cab," Mark said quickly, walking toward the front door.

"Actually, sir, your ride has been waiting for you."

"My what?"

The doorman nodded to the other end of the driveway as he held open the door for Mark to step through. Following his gaze, Mark groaned when he saw Derek leaning against a red sports car, his arms folded over his chest as he watched Mark's conversation with the doorman.

"That is not my ride."

The doorman frowned and hesitated for a moment. "But he said…do you need me to call security, sir?"

Mark sighed and looked back at Derek before shaking his head. "Nah. I'll take care of it."

He handed the doorman the tip he'd been expecting before making his way down the driveway toward Derek.

"A Jaguar, Derek? Really?" Mark called out as he got closer. "How many times did we go over this? That piece of junk is overpriced and impossible to maintain, man. If you're going to drop a hundred grand, at least get yourself a ride you're not going to have to replace in three to five years."

Derek smirked and shook his head, twirling the keys between his fingers. "Can't drop that kind of cash on a car these days, is that it?"

"Oh, you have no idea." This time it was Mark's turn to smirk as he thought about the pair of Porsches he and Lexie had treated themselves to for their fifteenth wedding anniversary a few years back. "What are you doing here, Derek?"

"I heard you were leaving today."

"So you thought you'd come say goodbye?"

"We need to talk, Mark. I figured you might need a ride to the airport, and that would give us a chance to have that talk."

"Did you talk to Addison?"

"I did."

"Then I have nothing to say to you." Mark paused and glanced at his watch. "But I am late, and the car looks new enough to still go fast."

"Just picked it up last month."

Mark sighed and nodded against his better judgment. "Alright, pop the trunk."

"So, uh, when did you and Addison become friends again?" Mark asked, tapping his fingers lightly on the door handle as Derek maneuvered his way through the streets of Manhattan. "I thought maybe the divorce would have killed that relationship."

"For a while, I thought it had. We put five more years into that marriage after…well, after you slept with her. I think when we finally threw in the towel, we were both pretty bitter about it. We didn't speak for another five years after that."

"So what happened?"

"She moved on, fell in love again, got remarried…and then her husband developed a glioma. I don't think I've been quite as shocked as I was the day I walked into an exam room to meet my new patient, and found him sitting there with my pregnant ex-wife."

"Pregnant?"

Derek nodded. "She was five months when I saw them," he said. "They'd already been to a half dozen of the best neurosurgeons up and down the Eastern seaboard, but when none of them could help, I guess she figured it was time to bite the bullet and come to me."

"And you removed the tumor?"

"Nope. I told her there was nothing I could do. This was thirteen years ago, Mark. There was no viable treatment for a malignant glioma back then."

"So Addie's husband is dead?"

Derek shook his head. "She wouldn't take no for an answer. She did her research and found a clinical trial out in Seattle…"

"The Grey-Sloan viral method." Mark flashed a knowing grin as he interrupted Derek.

"Yeah." Derek paused and considered the name. "Meredith's trial. I'll admit I didn't give it much credence when Addie first told me about it."

"No one did. It drove Lexie nuts."

"Lexie?" Derek paused and frowned as he turned the name over in his head. "You mean Alexandra Sloan?"

"You know her?"

Derek shrugged. "Only by reputation. We've been introduced at a few conferences over the years, but she's not exactly the friendly sort."

Mark laughed. "She's actually very friendly. I think maybe she just doesn't like you, Derek."

"How do you know that?"

"She's my wife."

"Your wife?" Derek stared incredulously at Mark.

"Of eighteen years, so wipe that shocked look off your face."

"Sorry," Derek muttered. "It's just…well, you never were the marrying type, Mark."

"Believe me, I would have been the first to tell you that before I started dating Lexie. And then one day, I realized I'd been with the same woman for two whole years, and I wasn't even bored. I figured if I could do that, why not give marriage a shot?"

"I guess I'm just surprised you went for someone so…I don't know, intelligent. I've heard her present at conferences, Mark, she's brilliant."

"Yeah, I know. I think I should be insulted by that comment."

"I didn't mean…"

"I know exactly what you meant, Derek. No, she's not the typical blonde bimbo I went for when I lived in New York. Seattle changed me, even before I met Lexie."

"Right." Derek nodded awkwardly. "So, why exactly does your wife not like me?"

"Because she's Meredith's sister and she knows that you're her nieces' deadbeat dad."

"I am not…"

"Yeah, I get it, you didn't open the damn letters. I heard. And I really don't care. Fact is, the story Lexie knows is that you're a deadbeat dad who walked out on her sister when she needed you the most."

"And that's…that's what my girls think too?"

Mark clenched his fists at Derek's use of the term 'my' but kept them firmly in his lap. "No," he said slowly. "They grew up thinking that Meredith didn't know who you were."

"What do you mean?"

"Meredith told them the story of how you two met, only she stopped at the point where she woke up in the morning and didn't remember your name. Until Annie saw a copy of her birth certificate, both those girls thought you'd been a one night stand who had no clue they even existed."

"Wait…you expect me to believe that Meredith let people believe she'd had a drunken one night stand and didn't even know who the father of her baby was? Even though she could have told people I didn't want to be part of their lives?"

"I don't really care what you believe, Derek. That's the truth."

"But it makes her look terrible…why would she do that?"

Mark frowned and stared at Derek for a moment. "You really didn't know her at all, did you?"

"Of course I knew her!"

"Tell me about her family, then. Tell me about her childhood."

"Her…look, just because I can't…"

"Meredith's parents divorced when she was five," Mark interrupted, putting an end to Derek's stammering. "Her mother moved her to Boston when she was seven, and she didn't see or hear from her father again until over twenty years later. Her mother's version of parenting was telling Meredith that she was useless. Meredith grew up believing her parents didn't want her, and she swore that as long she had any say in it, her daughters were not going to know that feeling. So if that meant she looked bad, so be it."

"Still, she didn't have to do that."

"Don't waste your breath. I had that argument with her the whole first year of their lives, Derek. Trust me, when Meredith sets her mind to something, you're better off staying out of the way – especially when her children are involved."

Derek sighed and nodded. "I wish I'd opened that damn letter."

"Would have saved us all a whole lot of trouble," Mark agreed.

"They're my kids, Mark," Derek said quietly. "I know I don't know them…I barely saw Annie for five minutes, and I've never met Evelyn…I don't know what she looks like, I don't know what sort of people they are, what they like, what they dislike…I don't know them, but I do love them, Mark, and I want to fix this."

Mark sighed heavily, running a hand over his face and staring out the window as Derek pulled up to the curb at the airport.

"I can fix this, can't I?" Derek hesitated when Mark didn't respond. "Mark?"

"I don't know," Mark admitted as he opened the car door. "I just don't know, Derek."