A/n- Hey thanks for the reviews. Hope you all have a good time reading this next chapter.

"Is the baby yours?" She asked again.

Derek stood and looked at her solemnly. "Yes."

Meredith's breath hitched in the back of her throat. "How could you?" she asked angrily.

"Well Meredith you see it is called the birds and the bees." He spat sarcastically.

"Shut up! You think this is funny? I can't believe you! When did you knock her up? Was it in New York?" She folded her arms across her chest.

"Yeah it was, and I didn't knock her up. She got pregnant, and it was a mistake." He said bitterly.

"You can say that again. Everything with her is a mistake."

Derek's blood boiled as he listened to Meredith trash talk Addison. "You know nothing about her!"

"Yeah? Well I know that she is a two faced hoar! She claims to be out of your life and then seduces you into bed so she can hold it against you! I know how she operates." Meredith stepped up closer to him her blood pressure rising.

"That is not how she 'operates'! She didn't seduce me. We were both drunk and we had sex together. It was a mutual decision." Derek ran a hand through his hair trying to calm down when it hit him. "How did you know about the baby?"

"What?"

"How did you know about the baby?" he asked as his voice rose. "I didn't tell you, in fact I had planned on telling you tonight, but someone bailed on dinner. I know Addison didn't tell you, and she isn't showing yet, so how do you know about the baby?" He stepped up close to her.

"I read your conversation." With that she held up his Blackberry.

"You what?" he yelled as he yanked it from her hands. "How could you? The conversations I have with Addison are none of your business. I don't go and tell her everything we talk about."

"Yes you do! Every time something goes wrong in our relationship you run crying off to her!"

"And she tells me to come and talk to you about it, but you never want to talk. God, Meredith will you ever accept the fact that Addison is a part of my life? Will you?" He shoved his hands through his hair frustrated.

"No, because I don't trust her! She wants you Derek. I can see it in her eyes; why do you think she slept with you?"

"Addison and I were married Meredith, married…not dating or engaged, but married. That night in New York was like any other night to us, but this time she begged me not to mention anything to you, because she didn't want our relationship screwed up. She kept silent for you and me, not for herself!"

They both stood still breathing heavy from all of the arguing. "She is having this baby whether you like it or not." Derek said in a controlled tone.

"Fine, but I don't want you to talk to her or hang out with her anymore." Meredith said firmly.

"What? Are you kidding me? She is carrying my child, but I am not supposed to see her and speak to her?"

"Yes. If you want to remain in this house then you have to abide by those rules."

"Then I'm out of here." Derek grabbed his duffel bag and began to pack. He shoved some clothes in and grabbed his leather jacket and keys.

Meredith stood in shock and watched him pack his stuff. "Where are you going?" She asked angrily.

"I'll be at Addison's, so don't call me." He slammed the door in her face and left. Meredith slammed her fist against the door. She had not thought that he would actually leave, and she had definitely not planned on him running to the arms of the woman he was 'forbidden' to see.

-Addison's Apartment- 2:30am-

Addison slowly shuffled into her hallway and to the door. She had no idea who could be coming to her house at this hour. She looked through the peephole and saw a disheveled looking Derek standing in her hall. She opened the door and stared at him. "Someone better be dying." She said groggily.

He gave her a small smile. "Can I come in?"

Addison noticed the solemnity in his demeanor and let him in. "Are you okay?" She asked as he stood frozen in her living room.

"I can't lose you Addi." He said barely above a whisper.

She walked in front of him and took his hands in hers. "I am right here. I hadn't planned on going anywhere."

He looked into her green eyes and a tear rolled down his cheek. "Meredith knows about the baby." He bit his bottom lip. He had never been the type of man to let his emotions show, but tonight he was going to cry. "She read my, our Blackberry conversation and put two and two together." He looked down at his feet. "She told me that if I wanted to stay with her that I couldn't see you or talk to you, and so I left."

Addison was touched by his devotion to her. "Derek…"

He shushed her. "No Addi, I am not going to apologize to her for this. I will for sleeping with you, because it was a mistake, but I won't say I am sorry for caring for you." He lovingly caressed her face. "Addi without Meredith I am miserable." She felt a sharp pain in her heart at his confession. "But without you…without you I would die."

She smiled up at him and blushed lightly. "Thanks."

"I mean it Addi. You know how a pair of Birkenstocks will fit anyone to begin with, and they aren't really comfortable until they mold to your feet and then they feel bad to everyone else?" Addison nodded her head, unsure of where he was going with this. "My heart is like that. It was new and then it molded to you, and it will always have an imprint of its original owner, no matter how hard Meredith tries to change it." He looked down and then back up at her. "Can I stay with you until this thing with me and Meredith is resolved?"

"Sure, I can always use the company. You can share the bed with me."

"No, I'll just sleep on the couch."

"Derek don't be ridiculous. That couch is not good for sleeping on. We are adults, we can share a bed. I mean we did share one for eleven years."

He sighed. "Fine, you are right, as always." He muttered.

She chuckled and patted his head. "Atta boy, you catch on fast. Come on, I am exhausted and so is your kid." She took his hand and led him to her bedroom.

At the mention of the baby he smiled. "How is the baby?"

"Good, I haven't had any morning sickness yet, so maybe I will luck out and not have any."

They both crawled into bed and lay down on their respective sides. "So when is your next doctor's appointment?"

"Next week why?" She asked as she turned out the light.

"I thought maybe I could go with you. I mean I want us to do this together."

Even though he could not see it he could hear the smile in her voice. "I would like that."

They pulled the covers up around them and unconsciously moved closer to one another. "Goodnight Ad."

"Goodnight Derek."

Derek wrapped his arms around her and smiled. He had had a bad day, but being with Addison at that exact moment had made the pain worth while.

-2 Weeks Later-

Derek was still staying with Addison and had made little conversation with Meredith. Addison had begun to have morning sickness, which she blamed on Derek. He would just nod and listen to her rant on and on as he held her hair back. He didn't understand why when they were married they could not talk like they were now. This confused him more than anything else in his life. Their baby was healthy and happy, and the doctor was pleased with the pregnancy. "Addison hurry up or we are going to be late!" Derek yelled as he stood at the front door waiting on her.

"I'm coming, gosh! I was putting on my makeup." She grabbed her bag and took her coat from his hands. It was mid- December which meant you had to wear a coat, gloves, hat, scarf, sweater; you name it you had to wear it. "Okay we can go now."

"Thank you." He said as he hurriedly ushered her out the door.

They had both fallen into a pattern that was much like it had been in New York. On the way to work they would talk about this and that, then in the evening Derek would cook dinner, they would work on their cases or watch a movie, and then go to bed. Addison knew that having Derek around at her house would not be a permanent thing, but she was enjoying it while it lasted. "So are you going to Adele's Christmas dinner?" Addison asked as they walked into the doctor's lounge.

"Yeah, I had planned on it. Are you?"

"Yep, she threatened me with bodily harm if I didn't attend." Their laughter was interrupted by a knock at the door. "Come in."

Meredith slowly cracked the door open. She was shocked to see both Derek and Addison changing into scrubs, together. Addison pulled her top on the rest of the way and smiled. "Don't worry, nothing happened." She looked between Meredith and Derek and saw that they wanted to be alone. "I have to go make rounds. I will see you later Derek. Meredith." She quickly left the room.

Meredith came in and shut the door. "So you two change together now?"

"Meredith I have seen everything she has to offer, and I have changed in front of her a million times. Trust me there is nothing sensual going on when we change. Now did you come in here to start another fight?" He asked as he sat down on a bench.

"No, actually I came to end one. Look I am sorry about what I said. I was and still am angry at you for sleeping with her, but I will get over it. I promise to not say anything about you seeing her as long as you promise to talk to me more." She stuck her hand out. "Deal?"

"Deal." He shook her hand and pulled her down next to him on the bench. He kissed the top of her head and smiled. "You want in on a major neuro. case?"

"You bet." They stood up together and walked out into the hall.

Derek saw Addison leaning against the nurses station with several of the nurses huddled around her. He jogged over towards her. "Addi?"

She looked up at him. "Derek…something…something is not right." At that moment her eyes rolled up into her head and she collapsed onto the floor. Her body began to seize.

Derek rushed over to her and placed her head in his lap so that it would not bang against the floor. "Meredith get the chief, and call Dr. Masterson her number is in my locker. Go Meredith!"

Meredith ran off down the hall to do as she was told. Derek pulled Addison's body into his arms and walked towards an elevator. Right as he stepped on she stopped seizing. "Come on Addi wake up, wake up." Derek held her limp body. She was so light, and pale. As the elevator doors opened he was met by the Chief and a stretcher. He laid Addison down on the stretcher, and prayed that she and their baby would be okay.

A/N- Okay I know that it is a cliffhanger, but I got to leave you wanting more. Remember more reviews…more motivation.