I was hoping to have this up sooner but it's been a hectic couple of weeks. It is the longest chapter in the story by far, so hopefully that makes up for the delay. Hope you enjoy.

Naomi swallowed nervously and then took a deep breath before saying, "You're pregnant, Addison."

Addison's eyes widened in shock and Derek's jaw dropped. "No, that's not possible," she insisted.

"I had them run the blood sample twice. I have both sets of results. They both say the same thing."

"No, Naomi, you told me I'm infertile. You said it would be nearly impossible to get pregnant, even with medical intervention. You said it would be the most shocking miracle of modern reproductive medicine."

Naomi nodded, "I did say that," she started. "And now that you are repeating it, I realize that it must have come across quite harsh. I'm sorry. I was clearly wrong."

"Wrong? How could you be wrong about that?" Derek asked, some sense of protectiveness surging from within in him. "You're a fertility specialist. Your job is to be right about people's fertility."

"The lab mixed your results with another patient. Allison Montgomery. I got the wrong results with your name on it."

Addison covered her face with her hands. "How? How does that happen?"

"I don't know, Addie. I'm sorry."

"What about this Allison woman? Does she know about the swap?" Derek asked. "Is that poor barren woman walking about thinking she's fertile? Can you imagine how she feels if she's been trying to get pregnant, and she thinks she can, but it's just not working? She must be going through hell, Naomi."

"The lab was supposed to contact her gynecologist to tell them about the mix up."

"How does that happen?!" Derek exclaimed. "How can they mix up the samples and how can you not know before you tell patients their results."

"It's just human error, Derek. I wish I had a better answer for you," Naomi explained.

"You need a new lab. What if it were pathology results? Do you know how dangerous that could have been? A false positive for a negative patient or a false negative for a positive patient? It would have killed someone" He rambled in concern, still gripping Addison's hand in his.

"I know. You are right. We will stop working with them after this," she promised. "But this already happened so we have to focus on this."

"So I'm not infertile?"

"No," Naomi mumbled anxiously, realizing that neither Addison or Derek is taking the news as well as she thought they would. "I'm sorry, Addison. It was a mistake."

"Naomi, I've spent the last few months thinking I won't be able to have any children. I built my new life around that news. I gave up on having a second child. And some poor woman is out there trying to get pregnant and failing because she thinks she's fertile when she's not."

"I know," Naomi agreed. "It's a terrible situation."

"You're sure she's pregnant? You're sure it's not someone else's results?" Derek asked.

"Yes," Naomi nodded. "But we can confirm with a home pregnancy test."

Addison's heart was pounding in her chest as she stared blankly ahead.

"Addie?" Naomi said softly.

"Nai, I think we need a few minutes," Derek told her.

Naomi nodded and excused herself to give the two of them their privacy. Derek moved to sit on the coffee table across from her so he could see her face. "You okay?"

"I'm pregnant."

"I heard."

"I thought I was infertile."

"I know."

"I didn't lie to you when I said that. I really thought I was infertile."

"I know."

"But I'm not infertile. I'm pregnant."

Derek nodded. "You are."

"How? I've had sex one time in the last few months. One time. How does someone go from infertile to instantly pregnant the one time she's had sex in recent history?"

"Could be worse. Could have been the shoe in rectum guy if he had played his cards right."

Addison couldn't help but laugh. "God, that would be awful."

"But it's us. We're having a baby."

"I can't believe this is happening," she sighed in disbelief, covering her face with her hands.

"Are you upset?" Derek asked unsurely. He couldn't help but think back to the last time she found out she was pregnant. Christopher hadn't been a planned pregnancy, per se. They weren't explicitly trying for a baby. They had just agreed that she'd stop taking birth control and they'd just go out their lives as usual. They assumed it would take months and months for her to get pregnant, especially because there was no special planning around her ovulation schedule. To their surprise, only three months later, Addison received the news of her pregnancy when she went to see her doctor for a routine pap-smear.

"Derek," she started, standing in front of the table he was seated at with his attending in the cafeteria. They were residents at the time, still young enough to believe they could have it all. "Do you have a minute? I need to tell you something and I know you're busy with surgeries for the rest of the day."

"Dr. Ford and I were just going over notes for my next surgery. He's got another case scheduled so he won't be with me." It wasn't his first solo surgery, but he still liked to have his attendings mentorship to prepare for the best outcome.

"I know. I'm sorry for interrupting," she said apologetically to the man at the table with Derek. "I promise it will only be a few minutes."

Dr. Ford looked at him. "You heard your wife, she needs to speak to you."

Derek pushed back his chair and got up to follow Addison to the leading outside of the building. "Honey, it's snowing and my coat is in the locker room. Can't we have this conversation inside?" he asked. He was in a pair of scrubs, rubbing his arms for warmth. "Aren't you cold?" he asked. Like him, she was in a pair of scrubs but had an extra layer of warmth from her lab coat; not that that was enough to protect her against a cold, snowy day in New York.

"No, I'm too distracted to be cold."

"Too distracted by what?"

"I just got some information that left me kind of surprised. It wasn't anything like I always thought it would be."

"It's too cold to flip girl into normal conversation. I don't know what we're talking about," Derek admitted.

"I just had a routine appointment with my gynecologist."

"Okay…" Derek seemed confused at first, but then very concerned. "Is everything okay? Is there something to worry about? You're only 28! Oh my god, I was not prepared for this today. How bad is it? What is it?"

"Derek, calm down. It's nothing bad. This is really not how I saw myself delivering this news but I have to tell someone and you have to be the first person I tell."

"Are you sick? Is something wrong? Please just tell me. You're freaking me out, Add."

"I'm pregnant."

"What?" he asked in disbelief.

"I'm pregnant."

"But you only got off the pill like three months ago. I thought it would take more time."

"So did I," she admitted. "But I guess we were wrong because I'm pregnant."

It took a few seconds for the words to sink in before a smile grew on his face. "Addie!" he practically squealed in her ear as he wrapped his arms around her and swept her off her feet.

She giggled at the unexpected gesture, wrapping her arms around his neck and pecking his lips before he could put her down. "I was so worried you'd be upset."

"Upset? Why would I be upset?"

"I don't know. We didn't expect it to happen so quickly. I didn't want you to feel like we rushed."

Derek shook his head, "I don't feel like we rushed and I'm not upset. I'm really happy, Addison. Are you upset?"

She could feel the tears glossing her eyes and she tried to blink them away before anyone could see her getting emotional in public. She shook her head to answer his question, "No, I'm not upset."

He reached up to her face to wipe away the tear that was rolling down her cheek. "Let's get you back inside. We can't have you freezing my baby out here," he teased.

And now here he was, 9 years later and asking her the same question. "Are you upset?"

Expect, unlike the first time, her answer was, "Yes, upset is an understatement. I'm furious."

"Addie…"

She cut him off before he could get passed her name. "I know I shouldn't be. I know I should be thrilled because I wanted this and this way, my kids will have the same father and be full siblings instead of half. And I actually know the father instead of using a sperm donor, and he's actually a decent person who wants to be present in the baby's life. I know all that. I know I should be grateful for it. But I'm just so fucking angry."

Derek nodded, gently rubbing her shoulder as she vented her frustration.

"I thought I was infertile. She told me I had no child bearing potential. I had spent months coming to terms. I was so angry at myself, at my body, for taking away my dreams of the future. And then she just comes back in here and tells me it was a lab error? My months of turmoil, months of feeling like my body betrayed me, months of therapy, were all for no reason? How does that even happen? And how does it keep happening to me? I spend over a decade thinking I'm married when I'm really not, I spend months thinking I'm infertile when I'm really not. Is there anything else that I think to be true about my identity that is not? And that poor woman, Allison, how is she supposed to process this news?"

"I know it's a lot to wrap your mind around," he admitted. "Are you considered...not keeping it?"

Addison turned to look at him in surprise, "No! Of course I'm keeping it. This is everything I wanted. I didn't exactly see it happening this way but still, the end result is what I wanted."

Derek nodded understandingly. "That's good to hear. Details aside, this is what I wanted too."

"But uh, maybe we can ask Naomi how the other woman takes the news. If she can't really afford to, maybe I can cover the cost of her fertility treatments or her adoption fees."

"That's really sweet of you, Add," he told her softly as he kept rubbing her back for comfort. "I'm sure she will appreciate the gesture. For now though, let's just focus on you. Do you want me to drive you home so you can get some rest?"

Addison met his eyes and nodded.

That night, he let Addison get her rest and process the news Naomi had given her while he made dinner, helped their son with his homework, and then got him ready for bed. As he was tucking their son in, Christopher looked up at him and asked, "Why is Mommy crying in her room?"

"She's just had a hard day, buddy. She needs some time to herself. She will be okay."

"She used to cry like that in her room when you didn't come home when we were living in New York."

"She did?" Derek asked, surprised that he'd never known that before.

Christopher nodded, "All the time. I stopped checking cuz I just knew why she was crying. It made me sad when she cried," he admitted. "But you're here now so why is she crying?"

"She just had a hard day at work."

"Did she lose a baby?"

"No," Derek assured his son. "She did the opposite, actually."

Christopher gave his father a confused look, "She found a baby?"

"Kind of. I guess you could say that," Derek replied, then tactfully changed the subject because he did not want to deliver the news to their son without Addison. "Hey, how about we go downstairs and watch an episode of Married with Children?"

"You said I'm not allowed to watch that."

"You're allowed when I'm with you and I give you permission."

"I watched an episode with Mom last week when I was sick."

"Oh, well you're allowed to watch with her when she lets too."

Christopher gave a satisfied nod at his father's response and got out of bed to go downstairs and watch his favorite show with his father. On the way down the stairs, Chris stopped and turned back to his father who was a few steps behind him. "But where did Mom find the baby?"

The next morning Addison tried to pull herself together and head into work. For Addison, that meant putting on an outfit that flaunted every curve while still maintaining intimidating professionalism. It meant perfectly coiffed hair and impressively precise make up to hide every bit of remnants of emotion from her breakdown the previous day.

"Woah, what's with the suit of armor?" Derek asked when she came down the stairs. He had already prepared a plate for her- plain toast, her go to breakfast throughout her first pregnancy.

"I just needed to feel more like myself," she explained as she took a bite of the toast.

He knew that what she really needed was a suit of armor to make herself seem more invincible than she felt. He knew that her clothing had become a type of defense mechanism for her. As far as he remembered, the last time she'd put so much effort was for her arrival in Seattle. "Well, you look beautiful."

"Derek," she warned tiredly. "Stop flirting."

"That wasn't flirting. I was just complimenting the mother of my child. I mean, children."

A look of annoyance (or was it anger?) flashed on her face. "I don't want to talk about that right now. I don't even want to think about it right now."

He nodded in response. "I know you don't. But we do have to talk about it. I'm going to be at the hospital for most of today to prep for surgery tomorrow. Then I've got an OR booked for 7:00am and I'll be at the hospital most of tomorrow. Then I will be here monitoring a only about a day before I have to head home."

"I'm not ready to talk about it right now and I don't know if I will be ready to talk about it before you leave and I need you to stop pressuring me"

Derek sighed, trying to be as understanding as possible. "I'm not pressuring you. I'm not trying to pressure you. I'm just trying to support you in the only way I know how."

"I know."

"I want to have a plan before I leave."

"Well, I don't want to feel rushed to make plans or decisions and I'm the pregnant one so my vote decides," she told him firmly.

Christopher coming down the stairs in his school uniform signaled the end of their conversation. Addison sent her former husband a firm glare to drop the conversation so their son doesn't catch on to what is happening.

"You ready to go, sweetheart?" Addison asked as she passed a banana to him. "You can eat that in the car. We are running late and I've got a patient."

"Hey, Chris, what do you say you go to school a little late today?" Derek asked him, earning a glare from Addison. Tardiness and truancy was not something she'd encourage onto their eight year old son. "I have to be at the hospital by 9:00 to prepare. So he won't be too late. We'll just have breakfast together and I'll take him right to school," he assured the woman glaring at him disapprovingly.

"Fine," she sighed. "Chris, do you want to go have breakfast with your dad and get to school a little late?"

"Yeah!" The child exclaimed happily.

"Great, it's settled them," Derek smiled at his son. "Chris, I'm gonna walk your mom to her car. You stay here and decide where we're gonna go for breakfast, okay?"

Chris nodded as Derek followed Addison to the door.

"Derek, as chivalrous as it is, I don't need an escort to my car," she told her ex as he followed behind her.

He reached for her car door to open it for her before she could, then gave her a charming smile. "Have a good day at work. I won't be there to check up on you today so be sure to listen to your body. If you feel tired or unwell, be sure to take some time to rest."

Addison sighed, "Please don't treat me like I'm suddenly disable."

"I'm not, I'm just trying to take care of you. Everyone needs someone to take care of them."

"We're divorced, Derek. It stopped being your job to take care of me a long time ago."

"We're not divorced because we were never legally married. Yet I took care of you for almost 12 years anyway. Well, if I'm being honest, it's probably more like the first 10 years that I paid enough attention to take care of you. Those last two years or so… they weren't my most attentive."

Hearing him admit his fault in the downfall of their marriage was refreshing. He had been more reflective about his own faults, more willing to own up to his mistakes and it was a relief for Addison to finally know he didn't place the blame solely on her and her affair.

"So I think we can agree that it's not a marriage license that determines if you care about someone."

"Not a valid one anyway," Addison teased with a small smile.

Were they already at a point where they could laugh about that?

As soon as Noami heard the sound of Addison's heels clicking against the floor, she left her coffee on the kitchen island and rushed toward the other woman's office. She stopped at the door in time to see Addison shed her black coat to reveal a knee length pencil skirt that clung to her frame and an equally, dark blue fitted blouse that revealed a perfectly tasteful amount of cleavage.

"What's with the outfit?" Naomi asked.

Addison turned to see Naomi at her door. "Nothing. Just felt like dressing up."

"You're already normally dressed up compared to everyone else."

"Yeah, the business casual thing was okay for a while but I'm over it. I'm more of a business formal kind of gal," Addison replied as she took a seat behind her desk. "Is there something you needed or are we just talking about fashion?"

"I wanted to check on you. You didn't answer my calls last night."

"I didn't feel like talking. I needed some space."

"I thought you would be happy about this," Noami admitted. "But you seem upset. Are you upset with me?" she asked unsurely.

Addison took a deep breath but didn't say anything. "I don't know," she admitted finally.

"You don't know if you're upset about this news or you don't know if you're upset with me?"

"Both."

"But you wanted a second child…" Naomi sounded confused. "I thought you'd be happy."

"Yes, I did. But you told me I couldn't have one. So I grieved this loss of a dream I had. I was so angry at myself for so long because I felt like my body was failing me and holding me back from having my dream. I had to come to terms with all of that. And I did. I learned to be happy with just me and Christopher and Derek and I finally found a balance to co-parent effectively. It was working. And then you show up and tell me you had the wrong test results and my months of inner turmoil were pointless? How do you expect me to react? Did you want a high five?"

"It wasn't my fault."

"But it was, Nai! If you had taken my desire to have another child seriously, you would have done more to help me. You did one blood test for a hormone panel and that's it. If you'd done an ultrasound, you may have realized the test results don't match up to what's on the screen. But you didn't do that! You told me to give up because it's a lost cause and I trusted you."

"I didn't want to give you false hope by running more tests."

"And look how that went…"

Naomi nodded, "You're right. I'm sorry. I really am."

"This changes everything I built my life around in Los Angeles."

"It doesn't have."

"Nai, I can barely keep Derek at arm's length when we're co-parenting an eight year old. He calls every single day, sometimes twice a day. And he doesn't just call and ask for Christopher. Do you know how hard it is to move on from a man who calls daily to check on you? And then he visits and he stays in my guest room and takes care of our son and pays attention to me and I keep telling myself that I can't let him get close to me again. We already failed as a couple once, I can't do that again."

"You don't have to do any of that again. You keep the same arrangement on parenting when the baby comes."

Addison almost rolled her eyes, "Derek can barely stay away from one child, you think having a second one is going to make the distance any easier? Because it's not. He's going to want to be here for the whole pregnancy, he'll want to be at every appointment. And once the baby comes, he will want to be there for everything. The first time it rolls over, the first smile, the first laugh, the first time it eats baby food. He's not a hands off father."

"Addie, people would kill for a man like that to father their children."

"You think I don't know that?!" Addison raised her voice.

"Then what's the problem."

"How do I move on from my failed marriage with a man I'm still in love with when he's constantly around, doing things that remind me why I love him in the first place?" Addison asked. "You and Sam barely get along and you hate working with him. Imagine having to be around him if he were constantly saying and doing all the things that made you marry him in the first place."

"Okay, I get that it's less than ideal but isn't that a small price to pay for getting your miracle baby?"

"It's not a miracle baby. It's just a baby because I'm not the eggless wonder I thought I was," Addison reminded her. "Nai, can you just please give me space? I need space."

After spending a majority of his day at the hospital preparing for his big surgery the following morning, Derek went over to the practice to check in on Addison before heading back to her house to get some rest before the next morning. He went into the kitchen to find Cooper, Violet, and Naomi standing around looking at Cooper's laptop.

"What's going on here?" Derek asked.

"Facebook stalking the new girl Pete is going out with tonight. She's a bartender."

"She looks like she's a porn star," Violet mumbled disapprovingly. "No way her boobs are real. What are those? Gs? Does it go up that high?"

"Why do you care about who Pete is seeing?" Derek asked as he poured himself a mug of coffee.

"That's what we do here," Cooper shrugged.

"Okay," Derek mumbled, choosing not to ask anymore questions even though he was still curious about what was going on. "Have you guys seen Addison?"

"I saw her this morning. She's dressed like an Upper East Side house wife who is hosting a charity fundraiser at her country club," Violet replied.

"It's kind of hot," Cooper added in a whisper. "No offense. Is it offensive to tell a guy that his ex-wife looks hot?"

"I meant, have you seen her lately. She ignored my texts all day."

"Oh, she's had patients all afternoon," Naomi told him. "I think she's doing a D&C now but I'm not sure because she hasn't really been too social with us either.."

"She's doing a termination?" Derek asked.

"No, early miscarriage."

Derek's eyes widened. "Is she okay?"

"Why wouldn't she be? She's been practicing medicine for twelve years. She's never seen a miscarriage before?" Violet asked, confused by Derek's concern.

"She has. Of course she has," Derek replied, looking at Naomi for help. When Naomi didn't say anything Derek added, "She just tends to get attached to her patients and she takes it really hard when things don't go well."

"Dude, you have got to cut the cord with your ex-wife," Cooper told him seriously. "Let's go get drinks tonight. There is this bar on La Cienega that I've literally never left alone. It never fails."

"Cooper, the man has a child."

"So? So does Sam but I took him there to meet girls and it worked," Cooper replied earning a glare from Naomi. "Oh, sorry. Forgot you're here."

Derek shook his head, "As great as that sounds, I have surgery early tomorrow morning and anytime outside of that I want to spend it with my son."

Cooper waited until Derek was out of earshot before turning to the two women in the room with him. "He's still in love with Addison, isn't he?"

"You recognize what being in love looks like? Wow. I'm impressed." Violet replied sarcastically. "What gave it away? Was it the way he looks at her? The way he talks about her? The fact that he comes out here to see her every chance he gets?"

"No, I didn't notice any of that. It was when he turned down guaranteed, no strings attached sex with a hot stranger."

Violet rolled her eyes, "Of course that was your give away."

So most of you guessed right! She is indeed pregnant. I was hoping it wouldn't be such a predicable plot twist but almost every review guessed it so I was clearly wrong haha.

Thoughts on the plot twist? How would you like to see it play out?