A/N: Sorry about the wait between chapters. I hope this chapter makes up for it; it's a long one, and all of the couples get a decent amount of time devoted to them. I hope you like it, and thank you so much for reading and for all your great feedback. I really appreciate it!

Addison smiled contently as she quietly made her way out of the twins' room. She had just put Carter and Colette to bed, and both had gone down easily, a rarity lately. She headed down the stairs, and made her way towards the living room, prepared to spend some time with Derek and Willa; but the sight in front of her caused her to linger a moment.

"So, wait," Willa began, looking up at Derek in confusion. "Is it left, together, right, together? Or is it right, together, left together?"

"Let's see," Derek smiled, taking Willa's little hand in his own. "It's right, together, left together. Right, together, left, together."

Addison couldn't help smiling as she watched her husband and daughter practice the wedding march together in the living room. "Do people still walk down the aisle like that?" she finally asked Derek with a chuckle.

Derek looked up at his wife and shrugged. "I don't know," he admitted, smiling down at Willa. "But now she's prepared either way."

"We're practicing for Uncle Mark and Aunt Lexie's wedding tomorrow," Willa explained to her mother.

"You're doing a very good job," Addison complimented.

"Do you want to practice too, Mommy?"

"Oh, I," Addison chuckled.

"You can practice with Daddy," Willa offered. "He taught me."

"I think that's a good idea, Willa," Derek approved, linking arms with Addison, as Willa climbed onto the couch so she could watch her parents together.

"She's amazing," Addison smiled, as she and Derek practiced the wedding march around the living room.

"I know," Derek agreed, smiling at his wife lovingly, before glancing over at Willa, who was watching her parents in delight. "I still can't get over how incredible she is."

"You know, I'm pretty sure that nobody does the wedding march anymore," Addison laughed.

"Yeah, you're probably right," Derek chuckled. "But if they do, she's prepared. Hey, Willa," he said, turning his attention to his daughter. "How's Mommy doing?"

"Good," Willa approved with a smile. "Very good."

Addison smiled at her daughter lovingly before leading Derek over to the couch and sitting down next to Willa. "Are you excited for tomorrow?" she asked her daughter, pulling Willa onto her lap, and hugging her close.

"Yeah," Willa nodded. "Really like being a flower girl."

"You're getting a lot of practice, aren't you?" Derek chuckled. "First Aunt Izzie and Uncle Alex's wedding, and now Uncle Mark and Aunt Lexie's wedding."

"Yeah," Willa agreed.

Derek smiled widely as he watched Addison cuddle Willa closer. Alex and Izzie's wedding had been just under a year ago, but since then, so much had changed. He and Addison had gone from being parents of one child to parents of three, and he felt incredibly lucky. But thinking about his family also reminded him of a conversation that he still needed to have with Addison – a conversation that he'd been putting off for four days now. The conversation he'd had with Richard.

"Daddy," Willa said, cutting into Derek's thoughts.

"Yes, Sweetie?"

"Want to practice more with me for Uncle Mark and Aunt Lexie's wedding?"

Derek met Addison's eyes and smiled. "I love her persistence and dedication. She definitely gets it from you."

"Really?" Addison laughed. "You think so?"

"Definitely," Derek nodded. "It will serve her well in med. school," he winked, before turning his attention back to his daughter. "Sure, Willa," he grinned. "Let's practice the wedding march some more."

xxxxx

"So, you have the rings, right?" Mark confirmed, smoothing down his tux.

Derek chuckled. "Of course I have the rings. I'm a wonderful best man."

"Good," Mark nodded. "So…" he trailed off. "Any words of wisdom?"

Derek grinned at his friend mischievously. "Lexie's great," he began with a chuckle. "But one woman for the rest of your life…it's not what God intended."

"Coming from the man who's married with three kids," Mark shot back with a smirk. "Did I really say those types of things to you at your first wedding?"

"Hey, I'm just getting started," Derek teased. "I still haven't fed you back your line about how God intended for us to have many, many women. A staggering number of women."

Mark shook his head in amusement. "I really was a terrible best man."

Derek shrugged. "Your pep talk wasn't the best," he admitted with a smirk. "I mean, it ended up being more about you than about me and Addison. But you're a good friend, Mark…the best friend I could ask for."

"Thanks," Mark grinned.

Derek smiled at his friend warmly. "You're going to be a great husband too," he continued earnestly. "Lexie's very lucky."

"Thanks man," Mark said sincerely.

"I mean it," Derek insisted, patting Mark's shoulder. "Now, come on. Let's get you married."

xxxxx

"I'm so proud of you," Carolyn beamed, as she and Mark prepared to make their way down the aisle together.

"Thank you," Mark smiled. "And thanks for being here today. And for walking me down the aisle. And for raising me."

"Mark," Carolyn chided. "You're like a son to me, and a brother to Derek. I couldn't imagine not being here for you today. Now, come on," Carolyn grinned, linking her arm with Mark's. "The music's starting. Let's get the show on the road."

Mark and Carolyn walked down the aisle first; followed by Izzie and Alex. And Mark couldn't help smiling as he watched the Karevs together. He knew that this past week had been hard on them; but based on the way they looked today, you'd never guess it. Today, they looked like the picture of happiness.

Addison and Archer walked down the aisle next. "Mommy looks pretty," Willa whispered to her father, as Derek lifted his daughter up so she could watch her mother and uncle walk down the aisle together. Derek could only see his wife from the back, but he knew Willa's assessment was spot on. And he couldn't help chuckling to himself as he remembered the song he'd written about Addison so many years ago, and how Mark had pitched in, rhyming gross anatomy class with Addison's fine ass. All these years later – and three kids later – the lyrics still held up.

And as he watched Addison and Archer, he couldn't help thinking about their relationship, and how he hoped that his own children had the close bond that Addison and Archer had. Sure, Archer could be an arrogant, self-righteous ass; but he was a good brother to Addison. There was no denying that.

Sam Bennett and Lexie's sister, Molly, walked down the aisle together next. And as they made their way towards the altar, Derek put Willa down, and kneeled down to her level. "You ready?" he asked his daughter with a smile.

Willa nodded eagerly, and Derek couldn't resist smiling at how adorable she looked in her little white dress with a deep purple sash around the waist; her dark brown hair, in loose waves, pinned half up and accented with hints of baby's breath flowers.

"You look like a princess," Derek complimented; and as Willa smiled her thanks, he firmed up his long-standing resolution – no dating for her until med. school. "So, remember, Willa," he continued. "Once you walk down the aisle, you can either sit with Grandma, or stand up on the altar with Mommy, okay?"

"Okay," Willa nodded earnestly. "Gonna stand with Mommy."

Derek smiled at his daughter lovingly, figuring that that would be her choice. "Okay," he agreed. "It looks like it's almost time for you to start walking, so get ready."

"Okay," Willa nodded, looking at the wedding planner, and waiting for her signal. "Hey, Daddy," she said, turning to face her father.

"Yes, Sweetie?"

"You look very handsome."

"Thank you, Willa," Derek chuckled, watching as the wedding planner gave Willa the go-ahead to begin walking down the aisle.

"Your daughter's precious," the wedding planner complimented, ripping Derek from his thoughts, as he proudly watched Willa walk towards the altar.

"Thank you," Derek smiled, reluctantly turning his attention away from Willa for a moment to meet the wedding planner's eyes.

"You two can start walking down the aisle," the wedding planner said, gesturing towards Derek and Meredith.

Derek nodded, and linked arms with Meredith, and they began making their way down the aisle.

Derek had always known Lexie was smart. A certified genius with a photographic memory, and a doctor – there were no two ways around it, Lexie was smart. But he hadn't realized just how intuitive she was. It was a fact that had become glaringly obvious as he and Meredith walked towards the altar. Lexie had worried that him and Meredith walking down the aisle together might be awkward or a bad idea; but he, Addison, and Mark had brushed her concerns off as nothing. But Lexie had been right.

And as Derek walked arm in arm with Meredith, he felt a dull pain in his stomach. Suddenly the faint scent of her lavender shampoo – a smell that he'd once loved – was overwhelming, and he swallowed the lump that had formed in his throat as he thought about the type of life he might have had if he'd stayed with Meredith, and not given him and Addison another shot. The type of life he might have had if he and Meredith had walked down the aisle, not as best man and maid of honor, but as husband and wife.

Maybe they'd be happy. But he knew that their happiness wouldn't even come close to the happiness that he and Addison had. Maybe they'd have a kid or two. But these kids wouldn't be Willa, Carter, and Colette; and that thought was unbearable. Maybe he'd build their dream house on the land he used to own. But it wouldn't be the home that he and Addison had made – the place where Willa had taken her first steps and said her first words, the place where Carter and Colette were conceived, the place where he'd proposed to Addison for a second (and final) time.

He swallowed hard and met Addison's eyes, feeling his heart melt a little as he took her in; she was holding Willa, her eyes reassuring, focused on him, making him feel like he was all that mattered to her.

Izzie must have picked up on the feeling too because she leaned in towards Addison and discretely whispered, "Hey, are you okay?"

Addison nodded, still keeping her eyes fixed on Derek. "I'm fine," she whispered back. "I just, I'm in love with my husband."

Izzie smiled. "I can tell that. Um, if you two are planning on getting a hotel room…or a bathroom stall…or a coat closet during the reception, I can watch Willa."

Addison blushed, amazed but not surprised that Izzie had the guts to say something like that inside a church, in the middle of a wedding. "I'll keep that in mind," she whispered.

The words had barely left her mouth when everyone's attention turned towards the back of the church. Lexie had begun to walk down the aisle.

To Lexie, it all felt like a dream. She was walking down the aisle towards the man of her dreams. When she first started working at Seattle Grace, she quickly learned about Mark Sloan and his reputation – a man-whore who was good for a quick screw, but nothing serious. But, over time, she got to know the real Mark Sloan – the kind, giving man, who wasn't just a world-class doctor, but an incredible guy as well. He was the type of man she dreamed of marrying. The type of man she dreamed of starting a family with. And the type of man she imagined herself growing old with.

She loved him. That went without saying. But as she took in the look of pure awe and adoration on Mark's face as she walked toward him, she loved him a little more than usual.

From there, everything happened so quickly. Vows were exchanged, happy tears were shed. And before she knew it, the minister was smiling at them fondly. "I now pronounce you husband and wife. You may kiss the bride."

xxxxx

"Hey, what do you say, we get out of here?" Mark whispered seductively into Lexie's ear, as they danced together.

"Mark," Lexie chastised. "It's our wedding. People will notice that we're missing."

"Not if we're quick," Mark disagreed

"Mark, there are a lot of people here celebrating with us."

"I'm not suggesting that we have sex in front of them," Mark defended. "But what kind of newlyweds would we be if we didn't have sex at our wedding reception?"

"Perfectly respectable ones," Lexie answered.

"Come on, Lex, we'll be quick."

"Not possible. This dress is ridiculously intricate. You wouldn't be able to bustle it back up."

"I hate to break it to you, Lexie," Mark smirked. "But I'm a surgeon. And I happen to be very good with my hands."

"Well, I'm not going to argue with that," Lexie grinned. "But, still, how many wedding dresses have you bustled lately?"

"I don't really know what you're asking me," Mark admitted. "I mean, I'm kind of hoping that that's some type of sexual innuendo or-"

"Mark," Lexie scolded, as they continued to dance together.

"Okay, fine," Mark conceded. "So I've never bustled a wedding dress before. But we can just call Addison or Izzie in to do it for you."

"And while we do that, I may as well just announce to them that we had sex…because they're obviously going to know."

"Well, I'm not sure an announcement is really necessary," Mark chuckled.

"Mark."

"I can guarantee you that Addison won't care," Mark insisted. "And I'm pretty sure Izzie won't either. So, let's just-"

"Dance," Lexie filled in quickly. "Let's just dance."

Mark smiled widely before leaning in and kissing her softly. "Will you at least think about it?" he bargained when they broke apart.

Lexie looked at her husband and gave him a mischievous smile. "I guess there's no harm in thinking about it."

xxxxx

"Okay, so what exactly did your husband say to my husband?" Izzie asked Addison, as they watched Derek dance with Willa. "Because whatever it was, it worked."

"I don't know," Addison admitted, reluctantly turning her attention away from her husband and daughter to meet Izzie's eyes. "Derek just said that he and Alex drank a couple of Blue Hawaiians and talked. He didn't go into specifics."

"Well, whatever he said, I appreciate it."

Addison smiled at her friend warmly. "I think that Alex just needed some time to realize what everyone else has already known…that he's going to be such a good dad. And he's going to be so good with a son. I guess Derek just kind of sped up the process."

Izzie smiled at the thought of Alex and Derek having a heart to heart over a couple of Blue Hawaiians. "Hey, I was thinking-." But she quickly cut herself off, a wide smile spreading across her face. "I'll, uh, I'll catch up with you later."

"Is everything okay?" Addison asked, confused by the abrupt end that Izzie had just brought their conversation to.

"Yeah, everything's fine," Izzie nodded. "I just, I'll see you in a little bit," she said, oblivious to the confused look on Addison's face as she turned and walked away.

She quickly spotted Alex in line at the bar, and made her way towards him.

"Hey," she smiled. "Come to the hotel lobby with me for a second?"

"I was just gonna order a drink," Alex said. "Can I meet you out there?"

"Lobby first, drink later," Izzie bargained.

"Okay," Alex agreed, smiling at his wife adoringly, as she led them out of the banquet hall and into the lobby.

"So, what's up?" Alex asked once they were alone.

"I…just a sec-." But she cut herself off, her hand immediately flying to her stomach.

"Hey, are you okay?" Alex asked, eyes widening in concern.

"Yeah, yeah," Izzie confirmed with a smile. "It's just…here," she said, taking Alex's hand, and pressing it against her stomach, over the spot where their son was kicking.

"Oh my god," Alex breathed, a wide smile spreading across his face.

Izzie felt her heart flutter as she watched the awestruck look on her husband's face. Feeling their son kick for the first time had rendered Alex – a man who had a response or a smart retort for everything – speechless. And she couldn't help smiling as she continued to watch her husband. The fear and doubt that had been so clear in his eyes just days earlier were nowhere to be found; the only thing she detected now was pure happiness.

"So, um, you wanna go back inside?" she asked, once their son had stopped kicking. "Maybe get that drink you were talking about?"

Alex shook his head. "Let's just wait out here a little longer," he suggested, pulling Izzie onto a nearby couch and gently rubbing the spot where he had felt their son kick moments earlier. "Maybe he'll start up again."

xxxxx

"Hey," Derek smiled, wrapping his arms around Addison's waist and leading her out onto the dance floor. "So, I just called the nanny to check in on Carter and Colette. And she said everything's going smoothly. And I didn't hear either of them crying hysterically in the background. So, I think we're good."

Addison smiled at her husband's words before pulling him in a little closer as they danced together. Sure, their marriage was strong, but seeing him walk down the aisle earlier in the day with Meredith had affected her in a way she hadn't expected. "I love you," she murmured, kissing him softly.

Derek met her eyes and smiled. "You're the only person I'd want to end up with," he whispered against her hair. "You know that, right? You and our kids…you know that?"

"Yeah," Addison nodded, smiling contently.

"Speaking of which, where's Willa?" Derek asked.

"Oh, she's with Archer," Addison laughed, motioning across the dance floor to where her brother was dancing with Willa. "Apparently, he's using her to pick up women."

"Oh, and how's that working out for him?" Derek asked in disgusted amusement.

"I don't know," Addison admitted. "It's still too soon to tell."

Derek chuckled, as he watched his brother-in-law with Willa. "You've got to admit, it's one of his better pick-up moves. He's actually a pretty good uncle to her. And she clearly loves him."

Addison nodded in agreement.

"And…it looks like he has a taker," Derek laughed, as an attractive blonde began making her way over to where Archer and Willa were dancing and began striking up a conversation.

"Now the real question is what is he going to do with Willa now that someone's showing interest in him?" Addison muttered, as she watched her brother and daughter closely, her heart melting a little when she saw Archer grab Bailey's son, Tucker, to dance with Willa.

"Derek," Addison chuckled, feeling her husband immediately tense up. "Come on," she laughed, as she watched her daughter dance with Tucker. "You've got to admit it's kind of cute."

"Mark my word, I'm going to chaperone every single school dance that she ever attends," Derek resolved adamantly.

Addison smiled at her husband adoringly; she loved how protective he was over Willa.

"Shepherds!" Bailey's voice cut in harshly; and Addison and Derek turned to look at her.

"I know, I know," Derek nodded, as he followed Bailey's gaze over to where Willa and Tucker were dancing like little grownups.

"I like Willa," Bailey began. "She's sweet and calm and well-mannered. But she's also one half McDreamy…and that's what worries me."

"Oh, come on, Miranda," Addison laughed. "It's adorable and you know it."

Bailey gave a slight concessionary nod before fixing her attention on Derek, a small smirk on her face. "Just wait until she's a teenager," she chuckled. "You're not going to know what to do with yourself."

"I'm struggling now," Derek admitted with a laugh.

"And I'm enjoying every second of it," Bailey grinned smugly before walking away to keep an eye on Willa and Tucker.

Derek watched her retreating form before fixing his attention on his wife. "So, uh, I need to talk to you about something," he began hesitantly.

"Is everything okay?" Addison asked in concern, registering the serious tone of her husband's voice. "Do you want to have this conversation outside?"

Derek shook his head. "No," he said, as they continued to dance together. "Because I'm pretty sure I know what I want to do. If I didn't, it would be a more serious conversation. But I think I made up my mind."

"About what?" Addison asked in confusion.

"Richard's retiring," Derek confided. "He wants to save his marriage, so he's stepping down as Chief so he can spend more time with Adele."

"And he offered you the position?" Addison asked.

"He did," Derek nodded. "Only, I don't think I can take it."

"Why not?" Addison asked in confusion.

"Because," Derek began, as he tucked a stray piece of hair behind Addison's ear. "Because Richard was a workaholic and it destroyed his marriage. You and I already got a glimpse of what that type of life looks like…and I could never do that again. And then today when I was walking down the aisle with Meredith, I just kept thinking about how happy I am that I ended up with you…and with our kids…and with our life. And I don't want to destroy what you and I have. Ever. In any way."

"So, you're going to turn Richard down?" Addison asked gently.

Derek nodded. "I think so. What do you think?"

Addison kissed her husband softly. "I think you're an incredible doctor, who worked really hard to get where he is. And I think you should take the position."

"You what?" Derek breathed in surprise.

"I think you should take the position, Der."

"But what about us?"

"Derek, you and I…we're strong. And I've never met a father who loves his children the way you love Willa, Carter, and Colette."

"So you don't think that me being Chief is going to change anything?"

"You may have more work," Addison conceded. "But I don't think it's going to change anything. Because you've shown time and time again where your priorities lay. And at the end of the day, if a person doesn't want to spend time with their family, they'll find an excuse not to…a work-related one, or a completely different one. And that's not you, Derek. That could never be you anymore."

"So, you don't think Richard should retire," Derek assessed knowingly.

Addison smiled at her husband warmly; Derek had picked up on the subtext of what she had just said. "I don't know," she admitted. "He's got to do what's right for him and Adele. But I'm telling you that as far as you and me are concerned, if you want to be Chief, I'm behind you one-hundred percent. And the kids are behind you too."

Derek smiled at his wife adoringly. "I-I don't know what I'm going to do," he confessed. "I mean, up until a couple of minutes ago, I was prepared to decline. Now…now…I guess I have to think about it." He met Addison's eyes and smiled. "You're incredible, you know that?" he whispered before kissing her softly.

"I'm proud of you, Derek," Addison murmured against his lips. "Really proud."

Derek smiled before drawing her in closer and kissing her deeply; and both he and Addison allowed themselves to get lost in the kiss.

"Uh, sorry to interrupt," Mark cut in, as Addison and Derek pulled away from each other, their eyes still clouded with desire. "I can see that you two are clearly having a moment, but I kind of need your help."

"Sure, Mark," Derek grinned, patting Mark on the shoulder. "I'm your best man, so whatever you need today, I'm your guy."

"Um, actually I need Addison," Mark admitted with a chuckle. "Or whichever one of you is better at bustling a wedding dress."