It all started with a call. One of Derek's sister, Kathleen is getting re-married and she wanted Addison to be one of her bridesmaids. For a minute, she thought about saying no. Her and Derek were divorced, she had no obligation on saying yes. But they were also her family, though the divorce ended her and Derek – her relationship with his sisters remained the same. So ultimately, she said yes.

Of course, she knew the consequences of saying yes brought. She knew that she'd have to go back to the place where memories of her past lied – the place where memories of Addison-and-Derek lied. But she didn't mind it, Kathleen was family. And besides, she didn't even have to stay in New York for long, she'll only need to fly there the day before the wedding and leave the day after the celebration. Everything was set, everything was okay until it wasn't…

A week before she had to fly back to New York, Kathleen had told her that the hotel where all the bridesmaids and the other guests were going to stay in was fully-booked. So, she asked her if maybe Addison could stay in the Shepherds home in Manhattan instead? Addison hesitated but Kathleen (and the other Shepherd sisters) persuaded her on saying yes. Promising her that they'd do their best in keeping Carolyn Shepherd away from her.

She laughed, thinking about what to say. After all, Derek had given her the brownstone when they got divorced. She could stay there instead. But after weighing the pros and cons of the situation, she decided on choosing to accept Kathleen's offer. It was going to be hard – being with people that are a part of her past. But then again, it was easier than letting herself drown in memories of her and Derek. It's easier to be stuck with his sisters than to be stuck with the Derek that she used to love.

Which brings her to where she is right now – outside the big oak doors of the Shepherds residence. Her and Derek's sisters were close, they considered her as the fifth Shepherd sister. But still, they haven't seen each other since the last time she went back to New York – before going to LA, she had decided to go back to New York so she could say goodbye to Savvy and her family. And to collect some things from the brownstone, like the rest of her clothes (and maybe a few of Derek's shirts). It's been months since they've all met and it's making her heart beat so fast. It's making her…

"Addison." Her heart almost stopped beating as she met her ex-husband's eyes as he opened the door.

It's been seven months since they last saw each other. She still remembered that night in Seattle. She went to his trailer to say goodbye before she went to New York; they shared a bottle of scotch while looking out the lake in Derek's land. This of course ultimately led to one to many rounds under the sheets with her ex-husband.

"One last time, we deserve this. We deserve a proper goodbye." that's what Derek told her before kissing her. She wanted to say no, to tell him to go screw himself. And tell him that he didn't deserve it, that he didn't deserve her. But she couldn't. Not when a part of her heart still beats for Derek Shepherd. Not when she knows that there wasn't supposed to be a one last time because they were supposed to have every day until eternity. So even if it was a bad idea, she still kissed him back.

"Derek, hi. I didn't expect to see you here." She chuckles lightly, leaning in to hug him.

"Why wouldn't you? I live here." He says teasingly, embracing his ex-wife.

"Well, you sure do look like it." She comments, eyeing his house clothes critically as she pulls away from the awkward hug with her ex-husband. "Are you here for Kathleen's wedding too?"

Derek hesitates for a moment. He has no obligation to tell her. Except he can't lie to Addison, especially not when they're in the city where they fell in love and fell apart.

"Not technically…" He shrugs. At Addison's encouraging nod, he continues. "I actually left Seattle. I've been staying here for almost five months now. Two months after you left, I uh, I moved back here. Permanently."

"Oh." She says quietly. "Why…"

But before she could say another word, Nancy and Kathleen came rushing towards her to give her a hug while Derek stood in the corner, looking at them with a mixture of amusement and sadness. His sisters really loved Addison, there was no denying that. Especially when they defended her to him when he started ranting about Addison, and that's also when he found out what really happened that night.

"So, Addison." Nancy begins, looking between Addison and Derek. "Kathleen forgot to tell you who you'd be sharing a room with. So, I guess I'll do the honors. The house is full, as always so you and Derek will have to share his room…that's going to be okay right?"

"I, uh…" She stammered. This is not what she expected when she'd agree to stay in their home but it's peek season for hotels in New York and she didn't want to be alone anyway. Besides, she didn't want to ruin Kathleen's day so she pulled her best smile. "Sure, it's okay with me. As long as it's okay with Derek."

"It's okay with me." Derek nodded, giving her a small smile.

"Well then," Kathleen beamed. "Derek why don't you help Addison bring her things to your room? We'll be in the kitchen. Liz and Amelia are competing on who's the better baker, you don't want to miss that."

His sisters hugged Addison one more time before leaving them in the foyer. Neither of them knew what to say. When they said goodbye to each other that night, they thought it would actually be the last time that they'll see each other. But faith seemed to have different plans.

"So…" She trails off uncomfortably.

"Let's go to my room." He suggests, taking her luggage.

"Yeah, I think that would be great." She agreed as the two of them went upstairs to Derek's bedroom.

Upon opening the bedroom, Derek felt his ex-wife's eyes lingering around the room. And he knew why, his room looked drastically different from the last time they went there. Instead of posters of The Clash, the walls of his room were filled with films and teared up pages from medical journals. Instead of old comics, his book shelf were filled of neurology books (and a few neonatology ones that Addison had left in the trailer). And then there's his desk, his old textbooks were replaced by a laptop and a picture of him and Addison.

"I didn't know you still had this." Addison mumbled softly as she eyed the picture. It wasn't a recent picture of them – actually, far from recent. It was a photo of them when she first stayed the night in his room.

"Oh, I uh, I wanted to personalize." He stammered. And I want you to be a part of my room. A part of my life again. He thinks, but he can't bring himself to say it outright. She just got there. It's too early to scare her off. "Mom moved to Connecticut and I had nowhere else to stay, so I asked her if I could use the house. It's just me most of the time but Kathleen's getting married in Manhattan so I volunteered to cater everyone here."

"That's very nice of you." She says softly, meeting his eyes. Addison could see something in them, he was looking at her the way he used to look at her. But before she could get lost in them, a nagging thought came to her mind. "Is Meredith okay with you moving back to New York?"

"No, but it doesn't matter what she thinks because we're not together anymore." He says, his eyes searching her face for some kind of sign.

"Oh." She says quietly. "I'm sorry. About you and Meredith."

"I'm not. But I'm sorry about us." For a minute, he thinks about pulling her in his arms to kiss her but one look at her made him decide not to. He can sense that he's making her uncomfortable so he changes the subject. "You know, I think we're going to be okay. I mean, we've slept in here before. It'll be just like the old times."

"Yeah, but we were married before." She retorts, and hopes that he didn't catch the shakiness in her voice.

"We weren't married either when we first shared this room." He reminds her smugly. Derek glances at Addison once again before giving her a reassuring smile. "Everything's going to be okay, I won't do anything to hurt you."

…

"Are you sure it's okay for me to sleep here?" Addison asks her boyfriend of six months once again as she emerges from his closet, clad in only her underwear and Derek's 'The Clash' t-shirt.

"It's going to be okay." He assures her, pulling her in bed with him. "And besides, it's not like we have any other choice. It's pouring really hard out there and we didn't bring a car with us."

"Which is your fault, by the way." She mutters through gritted teeth.

"My fault? Why is it my fault?" He asks defensively.

"You let Mark borrow your car when I told you not to and now, it's still getting repaired." She spats. Mark became Addison's best friend too when she started dating Derek but the two of them rarely got along. Especially when his 'escapades' involves ruining her and Derek's time together.

"You have a car too." He points out smugly.

"Yeah, I do." She concedes. "But Naomi borrowed it because my brother crashed Sam's car. Which by the way, I think Sam still doesn't know that Archer was the one who actually broke his car. And neither of us can tell him because Archer asked us nicely."

"See? We both have cars but other people are using it." He says teasingly, trying to ease the tension between him and his girlfriend.

A betraying chuckle escaped Addison's mouth. "That's true." She agrees, most of the tension disappearing as her lips twitch in to a smile. "Which is why even though I don't really believe in destiny, I think we belong with each other."

"Some things are meant to be." He says softly, returning the smile. "You know, I agree with you. I think you and I…we're meant to be."

"Yeah, me too." She murmurs, burying her face in Derek's chest. She settles there for a moment, soaking up her boyfriend's presence until something came into her mind. "Derek?"

"Hmmm?"

"Are you sure your mom's okay with me sleeping in here?" She asks worriedly. Addison knows a thing or two about facades (since she was literally born into a world that revolves around it). That's why even though Carolyn Shepherd always greeted her with a warm smile, she knew that Derek's mother is anything but warm towards her at all. She can't imagine his mom beaming with joy when Derek had told her that he'll let Addison sleep in his room.

"Why wouldn't she? We're not going to do anything." He says with feigned innocence but Addison caught a mischievous glint in his eyes.

"Oh no. Not tonight, Derek Shepherd. Absolutely not." She declares, untangling herself from Derek's arms. "I'm still trying to win over your mom and I don't think she'd appreciate it if I have sex with her son under her own roof."

"Oh come on, Addie, you don't need to win her over. My mom loves you." He insists. "And besides, that wasn't what I was thinking about."

Addison looked at her boyfriend in confusion as he walks across the room to get something from his desk.

"A momento." He explains as he walks back to his bed with a camera in his hand. "When mom finally gives me this house, I want a photo display on my desk."

"Okay." She says softly, moving behind Derek as he clicked a few photos of them together. "Hey, let me see." Her smile grew bigger as she scrolled through her and Derek's photos. "We should print these for our future offices or uh, your desk here."

"Yeah, we should." He agrees, smiling at her adoringly as she continued to stare at their photos. "Hey, Addie?"

"Yeah?"

"You know, I really think we're meant to be." He says softly, his piercing blue eyes meeting her pale blue-green ones. "Because you're you…and I won't do anything to hurt you. You're just…I never want to lose you; you get that right?"

"Yeah, I do." She breathes, leaning in to kiss him. And all of her fears of Derek's mother walking in on them disappearing.

…

"I won't do anything to hurt you." That's what Derek told her. Twice. In the same room. And Addison finds it funny because of the irony. Derek promised not to hurt her but he still did. More than anyone could do in a lifetime. She of course knows that she's at fault too and she's also caused him pain. But sometimes she feels like she's hurting more because of how Derek treated their marriage…because during the time when Derek was already loving someone else, she was still mourning the demise of their marriage. She had to go through it alone while Derek moved on.

Though it still hurts thinking about him, being in the same room with him but not having the same rights that she had when they were still married, he somehow fulfilled his promise – he gave Addison her own space most of the time. Which she's thankful for because she wouldn't know what to do if she continued to drown in the smell of his Tom Ford cologne or the feel of his elbow when he accidentally moved onto her side of the bed in the middle of the night.

She just keeps telling herself that it will all be over. The wedding was over, and now all she had to go through is the reception and another night with Derek before she goes back to LA. She just needs to wait it out because it will all be over before she knew it. And when she goes back to LA, she'll drown whatever happened and will happen with a few bottles of wine and a few boxes of chocolate with Naomi.

"Hi, everyone so, uh. Some of you may not know me. I'm Derek, Kathleen's brother." Her thoughts were cut off by Derek as he took the mic and stood in front of everyone. "I don't know what possessed her to ask me to do this but it's her special day. So I'd like to ask everyone to bear with me as I sing a very special song. To Kathleen and Jeremy…and to the woman I wrote this song for, this is for you."

Addison winces because she knows what's about to come. People from Seattle didn't know that Derek played the guitar. They didn't know that he could write songs but she did. Especially because he even wrote a song for her. He wrote her, her own love song and sang it to her during their own wedding in front of their friends and family.

Our eyes met over the cadaver

And I knew I had to have her

Has the mitral valve gotten too thick?

Is that what made our cadaver so sick?

She closed her eyes. Trying to shake the memories of that summer out of her head. But she couldn't. All she could see was Derek's piercing blue eyes as he looked at her adoringly while she made perfect incisions. They both mesmerized each other the moment they met, from being two of the smartest people in their gross anatomy class to simply being themselves. It wasn't a surprise that they fell for each other that easily.

What surprised a lot of people though is the fact that Columbia med's golden couple separated – divorced actually. They knew about the infidelity of both spouses, of course, but no one ever expected that to happen. Because Addison-and-Derek (or Derek-and-Addison, depending on who you asked) were perfect together. Everyone always said that they were meant to be. Together they made magic, they made a lot of people believe that it could be possible to meet the love of your life during the most unexpected times. They made people believe that two young, jaded yet successful people can make it work.

Addison Montgomery, I met her in the summer she –

Was cutting up a very dead body

And in her eyes, I saw my life

I knew that she would be my wife

Addison felt the eyes of the guests on her as Derek mentioned her name. From the mixture of amusement and hope in Derek's sisters' faces to the disapproving look that she was getting from Carolyn, it was suffocating. Especially because it was combining with her thoughts – about how Derek used to insist that he would marry her even when they were still only in med school.

"When we get married…" That's how he always starts. Whether they were studying for quizzes or just lounging around together, he'd always find a way to bring that topic up. He'd always tell her what he imagined their life would be like when they get married. He used to say that he had a feeling that they'd have children before their tenth anniversary. And they'd be spending their 15th year anniversary as a married couple in the Hamptons, when they buy a house there (which they did).

All of those plans didn't happen of course, because of the accumulation of his indifference and both of their infidelities. And that made Addison's heart ache, it wasn't supposed to be like this. They weren't supposed to be divorced. They weren't supposed to cheat on each other. She wasn't supposed to end up alone and unhappy. He wasn't supposed to fall out of love with her. And she wasn't supposed to miss him because he was supposed to be there. They were supposed to be together. It was supposed to be their twelfth anniversary that year and they were supposed to celebrate it.

And she would breathe the life back into me

From every day until eternity

Addison's breath hitched as Derek sang the last line. Every day until eternity. She used to tease him about that so many times during their marriage. She'd tell him how cheesy it was and he'd always insist that it isn't and he actually thinks they'd last until eternity. And after that, she'd stop teasing him to kiss him and tell him that she agrees. That she also thinks that they will last until eternity because she's her and he's him. They were Addison-and-Derek. A couple of clams in a shell, a couple of peas in a pod. They were always meant to be.

But through the years, Addison is thinking if maybe they were just meant to meet so they could teach other a lesson – to never take for granted someone you love. She's surely learned that lesson and she hoped that Derek does too because she wants to believe that the sacrifice that she made for him to be happy was worth it. That letting Derek go was worth it.

She doesn't know what's going to happen if Derek ends up hurting someone else, she could take it but she's not sure if someone else will. And she doesn't want Derek to end up alone and unhappy because even after all the pain he's caused her, all she wants is for him to be happy because lately she's been thinking that maybe love means wanting the other person to be happy even if it means that they can't stay with you.

"I'm just going to the bathroom." She murmurs as Derek stops singing and reality finally hit, that's when she realized that Derek was looking at her during the entire song. And it's intoxicating, he's intoxicating.

With that, she stands up and leave, not bothering on looking back at the people sitting next to her. Or when she felt Derek going after her. She can't look back, not when he's looking at her the way he used to. When he's singing to her the song, he wrote for her. Not when he's promising not to hurt her but it's all he ever does. Her heart was beating for Derek Shepherd but she also knew that if she didn't stop herself, he could also be the reason why her heart would stop beating.

"Addie." He calls after her as they reach the mini-garden outside of the plaza. "Addison, let's talk. Or at least just look at me, please."

She sighs before stopping to face him, "Why would you do that? Why would you sing our song in front of everyone, in front of me? And for the love of God, please stop looking at me like that. It's all you've ever done since I got here and it's absolutely intoxicating."

"Addison, I didn't know you were coming to the wedding and Kathleen asked me so I said yes." He explains, running his hand through his hair. "And do you really think that I want to look at you? That maybe I'd rather look at other single women that I didn't have a history with. I want to do it so badly but I can't. Not when I'm still in love with you."

"You're in love with me?" She scoffs. "Well you have a great way in showing it, Derek. And it's too late for this. Do you know how long I've been waiting for you to say that? Years even before the affair. And now it's all over."

"No, we could…we could." He swallows the lump forming in his throat, trying to wrack his brain for something to say to his ex-wife. "Stay in New York with me, Addie. We can start all over again here. Just you and me."

"Derek we've already had our chance in Seattle, we've already tried…"

"No, you tried. I didn't because I wasn't ready but I am now." He promises. "Just give me a chance and I promise you that I'll always be there. I'll never let you drown again."

Addison's eyes widened in surprise. If it was anyone else, she would've disregarded what he said but with the way he's looking at her, she knows that he knows.

"Did Mark…it's not his story to tell." She says shakily, feeling her knees began to buckle.

"My sisters told me." He explains, dodging the bullet for his best friend. "Why didn't you tell me that you almost drowned in our tub when Mark came to see you that night?"

"Derek…"

"I'm so sorry, Addison." He says softly, his apologetic piercing blue eyes meeting her pale blue-green sad ones. "I didn't remember what day it was, and you had to go through Martin's first death anniversary alone…Addie, that night and the other one wasn't your fault. We didn't know that you'd develop post-partum psychosis – "

"Stop." She cuts in harshly, tears streaming down her cheeks. "Stop saying that because it will never change a thing. Martin drowned and it's my fault. He's gone and we're…we're…"

But before she could get anything out, her words dissolved into sobs. She fell into Derek's arms as her knees finally gave up on her. This not what she expected. Not at all. Being reminded of the night she failed to save their child and the night their marriage was destroyed was too much. And she can hardly breathe.

"I won't say anything about it anymore." Derek says quietly, running his fingers through her hair to sooth her. "But you have to believe me when I tell you that it's not your fault. And that I want to try again with you. We can still fix us, Addison."

"Why do you do that?" She asks, regaining her strength.

"Do what?" He asks confusedly as their eyes meet.

"Take back everything you say." She clarifies, sighing in defeat. "You promised me you'd love me for every day until eternity but that barely lasted eleven years because things change and I'm not the love of your life anymore. And now you're here, asking me for another chance because you're still in love with me. Really, Derek, you're the most indecisive person I have ever met."

Derek looked at her – really looked at her – and realized how much damage he's caused. Addison never falls off her feet, she always held her head up high. And the Addison in front of him was nothing like her at all. Even though she was arguing with him, her voice was raw. Defeated.

"I was okay with you changing your mind the first time because even if I wanted to, I can't stop you. I'd never stop you from leaving if that's what you wanted." She continued when he stayed silent. "But this…I can't be okay with this. I can't be okay with you playing with my heart again. Because even if you've hurt me so damn much, I still love you. I love you so much that I had to move across the country because seeing you love someone else was worse than the pain you've already inflicted."

"Addison, I..." He couldn't think of anything to say, so instead, he pulled her in and kissed her softly…hesitantly, hoping that it would be enough to make her feel his love.

His heart soared so high when he felt her kiss him back, wrapping her arms around his neck, deepening the kiss. It was soft and sweet. Loving, even. And even if he knew that Addison still felt a little hesitation, maybe this could be a start for the two of them.

"Derek, we can't. Not anymore." She breathes, untangling herself from his arms.

"Addison, we can still have a chance." He insists.

"But what if we ruin it again?" She asks sadly. "I know you think that this is some kind of sign from the universe. You and I seeing each other again means maybe we can still have another chance at this. But what if faith brought us back together not because we deserve happy ending but to give us another shot at ending it right? Or what if I say yes and you fall in love with someone else again? It almost killed me the first time; I don't think I can go through that again. Derek, what if…"

"What if we can make it work?" He interrupts. "What if I tell you that I'm so in love with you that sometimes I forget how to breathe? Because you're the only person who can breathe the life back into me. What if I tell you that I don't think I can ever fall in love with someone else again because you're still the love of my life? Addison, I know it's a lot to ask and maybe I don't deserve to ask you. But I want it, I want to spend the rest of my life with you."

"I want that too…" She says quietly. "But Derek, I can't move across the country for you again."

"So, don't." He says softly, taking her hands in his. "Extend your stay for at least a few weeks, just to let me prove to you how much I want to be with you. After that, I'll let you decide."

She wants to say no because staying meant opening herself to a chance of getting hurt again. But she can't. She said it herself, don't say no to an opportunity that could've changed your life. So even if it's a risk, it's a risk that she's willing to take. Derek was worth it.

"Okay. I'll cancel my flight." She declares, her lips curling into a soft smile.

"Really? You'll cancel?"

"Yeah." It's Derek's turn to smile at that. And before Addison knew it, his lips were on hers.

She immediately responded in kind, pulling Derek closer as she wrapped her arms around his neck. The kiss was soft and slow until their tongues meshed with each other. Their kiss becoming sensual and languid.

"Do you want to get out of here?" He asks, breaking away from the kiss.

"Yeah." She breathes, knowing that it's only a matter of time before the two of them end up in a truly compromising position.

…

After a few weeks, they stop counting because Addison chose to stay in New York with Derek. And besides, why would you count days when you had every day until eternity with the person you love?

Derek really proved himself to Addison. Especially after she made the decision to stay permanently. He almost never left her side; he was always right there – ready to give her what she needs. And she did the same with him. The two of them spend their days learning how to love each other again. By doing the simple things; going on dates, lounging in the Shepherds living room with a bottle of merlot after a week of work, and sometimes cleaning the house together, they were able to somehow repair their relationship.

Then there were the bigger moments for them. Like when Derek kneeled down once again to ask Addison to marry him, using his father's ring to propose because he knew that Addison was the right woman; the sheer happiness on their faces when Addison walked down the aisle; the shock and delight on their faces when Nancy confirmed that Addison was pregnant; and then to recently, watching their daughter's milestones.

Katherine Martina Shepherd was born two years after her aunt Kathleen's wedding. And she was truly the perfect combination of her parents. From her father's dark hair, to her mother's pale blue-green eyes then to the dimples that she definitely inherited from her father. She was absolutely beautiful, and based from her parents' observation, she was also smart because at 11 months old she was already a master at crawling and she can already say the words "mama" and "dada" (much to her parents delight).

"Come on, Kath. You can do it. Walk to daddy." Derek coaches his daughter as she wobbles around his mother's – no, his and Addison's living room (Carolyn finally gave him the house).

"Honey?" He hears Addison call out from the foyer.

"In the living room." He calls back from his place on the couch, holding a digital camera as their daughter's eyes wandered to find her mother.

Addison smiles widely as she enters their living room, the sight of her husband looking at their daughter adoringly as she took wobbly steps from the other side of the living room making her heart melt. She never expected this to happen when she attended Kathleen's wedding. The life that she and Derek had right now used to be a pipedream. And she can't help but think that if she had said no in sharing a room with Derek or if he hadn't sung the song that he wrote for her, this would've never happened. So she's grateful that it did. Beyond eternity grateful.

"She took her first steps without me?" She asked her husband as she sits down beside him, her voice laced with a mixture of excitement and disappointment.

"Not yet." He shakes his head, wrapping an around Addison's shoulders. Derek glances at his daughter before giving his wife a teasing smile. "I think she's waiting for her mama. Isn't that right, Kath? You're waiting for mama to come home?"

"Of course she is." She agrees, fixing her attention to her daughter who was looking at her expectantly. "Mama's here, Kath. Come on, come here so mama can hug you."

For a minute, the two of them thought their daughter would end up crawling towards them like she does all the time. But to their surprise, Kath was able to stand up, using the table as her leverage like she always does… but this time it's different. Little Katherine Shepherd alternated from a fast to a slow pace as she took wobbly steps towards where her parents were sitting. Beaming when she finally reached her mother's leg, wrapping her arms around it.

"You're so smart, Kath." Addison says softly, standing up to scoop her daughter in her arms. "I love you. You make mama so proud."

"Hey." Derek chimed in, wrapping his arms around his wife's waist from behind. "Dada loves you too, Kath. You know that right?"

"Of course she does because dada spoils her with toys." Addison says teasingly.

"And mama spoils her with shoes." He reminds her smugly, resting his chin on her shoulder as he made funny faces to their daughter.

And as the three of them stood together, Addison can't help but smile. Her and Derek weren't a perfect couple, they'd always have a tainted past. And all their plans from when they were in med school never happened but she'd settle for this. Her and Derek's life right now is more than enough to heal the pain. Their lives weren't over yet, they still have a long journey to go through but Addison didn't mind it. The life that they were living was simple – it was a simple yet beautiful life and it was more than worth it to fight for. Derek and their family was worth it. But besides that, she's really glad that she's going to have Derek to share every day until eternity with because she can't think of anyone else that she'd willingly choose to spend the rest of her life with except him.

"Derek?"

"Hmm?"

"I love you." She whispered, tilting her head to meet his eyes.

"Yeah?" He smiled softly.

Addison leaned in to kiss him gently. "Yeah, for every day until eternity."