A/N: So I was going to make this into a chapter fic, but I already have two so I combined and did other stuff and made it into a oneshot. Takes place right before the affair then after…you'll see.

It's Addek. And I own nothing.

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Addison's hand shook as she saw the pink plus sign on the pregnancy test. She was crying, but out of joy. A baby. She was going to have a baby. Derek's baby. She practically ran up to the OR where Derek was doing surgery and paced around. The twenty remaining minutes of his surgery were days, Addison was sure. When he finished she ran down to him.

"Derek, I have news, big news."

"Addie, not now. I have things to do."

"But Derek, you'll want to hear it."

"Addison, I don't care right now. I'll talk to you later. Aren't you off by now anyway?"

"Derek, just listen to me."

"Damn it, Addie. Just leave me alone. Go tell Mark."

Addison was unbelievably hurt. She felt like crying. Her husband didn't care about their baby. Well, he might care. He didn't care to hear the news though. Addison looked down at her stomach.

"I'm pregnant," she yelled down the hall. But no one was there.

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"Mark, can you…could you come over?"

Addison's voice was urgent. Mark was concerned immediately for her well-being. "Addie, what's wrong?"

"Can you just come over?" She said it though tears.

"I'll be right there."

Twenty minutes later and Addison opened the door to Mark. He engulfed her in a hug and she immediately started crying.

"Addie, what's going on?"

"I'm pregnant. I tried to tell Derek, I told him it was important and big but he didn't care. He told me to leave him alone. Not to talk to him."

"Oh, Addison. Congratulations." He offered her a crooked smile. "When did you find out?"

"Today. After work. I suspected, but I figured a cheap test could tell me. And then I waited for his surgery to be over and I tried to tell him…but…"

Mark hugged her tightly. "I'm so happy for you. So happy, Addie. I know you've wanted a baby."

Addison smiled and looked up at him. And there he was. The eyes were the same. And before she knew what she was doing, before she cared, she kissed him.

Mark was surprised but quickly held Addison's face with his hands and kissed her back. What he had wanted for so, so long. And here she was. Kissing him. He inhaled deeply, and traced his fingers in her hair.

They broke apart, and Mark waited to gauge Addison's reaction. She stood on her tiptoes and leaned towards Mark's ear. "Take me to bed," she whispered. "Let me forget."

And Mark knew this was one request he wouldn't deny any woman. He picked her up gently and began his ascent up the stairs, to the bedroom. And Addison started her descent into hell.

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"Derek, you can't do this."

He said nothing, only picked up their bedspread and added it to the pile of clothes.

"Derek, we have to talk about this, you have to give me a chance to explain. What are you doing? What are you doing with my clothes, Derek?" She was hysterical now. "It was one time. I know that's what people say. I know that's what always gets said. It's just, I don't even know how it happened, I don't know what I was thinking, he was just here, he was just here-" And you weren't. You weren't ever here. You weren't ever anywhere near where I was.

"You screw my best friend and all you can say 'he was just here?'" He threw the clothes outside. The rain was pouring. "Get out."

"No."

"Get out."

"No, no, I'm not going. We're going to talk about this, we're going to discuss this."

"Get out of my house. Now!"

"No. I'm holding my ground. I'm holding my ground. We don't quit."

"Get out."

"What are you doing?" And then he threw her. Outside. Into the storm. "Derek. No."

His wife. Pressed to his best friend's body. His wife, fucking his best friend. Derek couldn't breathe. It didn't make sense.

He was throwing his child out in the rain. Did he know that? He didn't. He didn't because he didn't talk when she had the biggest news to tell him. "Please." She cried, because it seemed the only thing to do now.

He opened the door to his wife.

"I'm sorry. I'm sorry. You have to give me a chance. You have to give me a chance to show you how sorry I am." She tried to touch him, to show him, but he pushed her away.

"I'm going to go. You stay. I'll get my clothes in the morning."

"No no no no no no. We can survive this. Derek. We can survive this. We're…we're AddisonandDerek." And once, that had meant so much. Once that had signified so much.

"I can't look at you. I look at you and I feel nauseous. I just…we're not DerekandAddison anymore."

Addison stopped. Her tears, gone. "If you go now…if you go now, we are not going to get through this. If you go now, we don't have a chance. We don't have a chance, if you go now. If you go…"

And the door slammed.

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That was two months ago. And now, Addison was sitting on a plane. To Seattle. She was three months pregnant. Three and a half. She was showing. Not enough, but everyone who knew her knew she was pregnant. Nancy, Savvy, Mark, her boss. Everyone in New York. Derek still didn't. No one knew where he was. Until Addison had gotten that call from Richard that morning. Derek was in Seattle. Seattle. A tiny little dot on a map that meant nothing to her before yesterday.

Mark was fully aware the child was Derek's. He was the first person Addison had told. But he also said he'd be willing to raise it as his own. Addison was touched, she really was. She and Mark were closer now, after Derek had left. Once again, Mark had been there. He had been there, and Addison felt comfortable with him. But she didn't know if she could continue sleeping with him, living with him, whatever the hell she was doing with him.

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She was pregnant. Derek looked at his wife and knew it in an instant. She was in all black, she was wearing a long coat, but Derek knew. She was pregnant. Mark had knocked her up. How convenient for her. It would make divorce all the easier though, if she was pregnant with Mark's baby. She strode over to him, Meredith looking at him confused.

"Hello," she said, sticking out her hand. "I'm Addison Shepherd."

Oh, she was good. Derek watched her lips curve into an evil smile as Meredith was running through a mental list of possibilities. Sister? Cousin? Pure coincidence?

"And you must be the woman who's been screwing my husband."

Meredith looked at Derek, who had no words for Meredith.

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"Addie, is it Derek's?"

Addison bowed her head. "Yes."

Richard nodded slowly. "What happened?"

"I slept with his best friend."

"Did Derek know about the baby?"

"I was going to tell him. He brushed me off. He doesn't know. So I slept with his best friend. It wasn't revenge, really. Mark was just there. Mark knew before Derek did."

"Are you going to tell Derek?"

"I don't know."

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It was her last day. She was leaving that night. Her case had gone wonderfully. Derek hadn't said a word to her after the first night. Addison had divorce papers ready. She figured it was what Derek wanted. She caught him talking to Meredith outside an elevator. She strode up. "Can I join in, or are you not into threesomes?"

Meredith left and Derek looked disgusted. "You really are Satan, you know that?"

Addison said nothing and took out the folder. She shoved the papers at Derek and watched him open the folder.

"Divorce papers."

"The ball's in your court. If you sign, I'll sign."

Derek pulled a pen out of his pocket. "Let me do that right now."

Addison nodded slowly, trying not to cry. She would be okay. Mark would make things…okay. He would make things okay.

"So have you and Mark picked out names for the baby you two have created?" He said, the pen poised.

Addison shook her head angrily. "Derek, did you ever think for just one second that maybe the baby isn't Mark's?"

Derek looked up and dropped the pen. "If the baby isn't Mark's…then whose baby…" he watched Addison's face, "I can't…it's not…oh my God."

"As much as right now I wish it was Mark's, the facts don't lie. I'm three and a half months pregnant. The only person I was having sex with three and a half months ago was-"

"Me." He massaged his temples. "You were pregnant and didn't think to tell me. Thanks a lot, Addison."

"Derek, I tried to tell you. The night I slept with Mark. That afternoon, I said I had news, big news. You brushed me off. You said you didn't care. You said to tell Mark. I tried to tell you. You didn't listen."

Derek recalled that afternoon. His face burned with shame. "Oh, Addie." He strode forward and hugged her. "Oh, sweet Addie. I'm so sorry. I'm so, so sorry." Derek was crying now, holding his wife tightly in his arms.

Addison didn't give into the hug at first, but then she saw the genuine tears and felt her own eyes getting wet. She held on tight and let go of her anger for the moment. She buried her face in the crook of Derek's neck and he held her tightly.

"I'm so sorry. Oh, Addie. I'm so so sorry. You have to give me a chance to show you how sorry I am."

Addison looked up at Derek at that and recalled the night which had been so painful in her memory. He leaned down after a moment of hesitation and kissed her, fusing his lips to hers.

"I love you, Addison. I'm so, so sorry. It's all my fault. If I had just stopped being such a self-absorbed bastard for one second and listened to you, you wouldn't have slept with Mark."

"It wasn't all your fault. Yes, I wouldn't have slept with him that night…but if you had continually been absent…but you didn't kiss him, Derek. I kissed Mark, and I-"

"Addie, enough. I didn't listen and I almost lost you. I'm so sorry."

Addison sniffled in response.

"Let's go home," Derek whispered quietly in her ear.

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One Year Later

"Lucy, smile for Daddy now. Come on. Come on, sweetie. Smile for Daddy."

A six-month old Lucy stared at her father from her mat on the floor as Addison walked through the front door of their New York brownstone. "Mommy's home."

Derek waltzed into the front room carrying Lucy. He kissed Addison quickly on the lips and she smiled. "How was your day with Daddy, little one?"

"It was wonderful, Mommy," Derek said in a mock baby voice. "I love Daddy, way more than Mommy."

"Is that so?"

"Don't worry, Addie. She'll come around for you too."

"I'm glad you're so positive of that fact."

"You know what else I'm pretty positive on?"

"What?"

"Lucy needs a sibling to keep her in line. You didn't have any siblings and look how you turned out."

Addison laughed. "Yeah, I'm terrible. A sibling, you say?"

"Just one. Maybe two. Or three."

Addison smiled. "I don't want to go through three more births."

"What about two?"

"We'll have to talk later."

"Right, sorry. We have small ears around, don't we?"

Addison smiled. It was the anniversary of the day Derek had found out she was pregnant and left Seattle. He had broken it off with Meredith, perhaps too harshly, but once he realized what he had put his wife through, Meredith's issues paled in comparison. Derek was sorry, he was, and once or twice Meredith crossed his mind. But compared to his wife, she was just a girl he met at a bar. Addison and Derek had had many fights involving Mark and Meredith and screamed at each other more often than not. But a few weeks after Lucy was born Derek finally forgave her once and for all, and two weeks after that Addison let go of Meredith. This wasn't to say that their life was by any means perfect now. But they made it work. Lucy Allison Shepherd had been born at 1:43 in the morning April 28th in a quiet wing of Mount Sinai hospital. Derek had cried, his sisters had laughed at the pictures of Derek crying, and Addison had been speechless. Suddenly she was the patient and someone else was delivering her baby.

She had broken it off with Mark. Derek and Mark were by no means friends again, but they talked when they had to and could be heading on that path if they so chose. Mark and Addison hadn't spoken since the phone call in which she had told Mark that Derek was back. Addison had told Derek that she had been staying with Mark, and it took Derek a while to get over it. But he had. He had. He swore over and over again that he wouldn't hold it against her, except in arguments, which was acceptable. Addison held Meredith against Derek in argument still.

Being AddisonandDerek (DerekandAddison if you were talking to Derek) meant something again. It signified a hell of a struggle for a beautiful relationship. It signified love.

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A/N: Cheesy, unrealistic, and random. But I needed a bit of that. You did too, I know it.