Summery: I think this will eventually be an Addek, but I am not certain yet. It is about Derek cheating on Addison and the fall out of that instead of her cheating. Enjoy!

AN: I know I dont own any part of Grey's Anatomy other than some scrub pants. You should get some they are uber comfy.

Prologue.

"Today was supposed to be a great day. Why has it turned out so wrong for me?" thought Addison. Her hands shook as she poured herself some wine. "Damn it." She said as she threw the bottle and glass in to the sink shattering both into a thousand pieces. She didn't care about it she just crumpled into a ball on the kitchen floor unable to get the images out of her head. They were beginning to haunt her.

Earlier that day

Addison bounded up the steps toward Derek and Mark's private practice. She was going to surprise her husband take him out to a celebratory dinner because of the great news she had for him. When she walked in she said hello to Sammy the receptionist like always and headed back to wait in his office. Before she reached the office Mark came out of an exam room with a look of pure shock on his face.

"Addie, what are you doing here?" Mark replied quickly trying to think of a way to get her far away from Derek's office.

"I am surprising Derek." Addison lost in her own world of cheerfulness.

"Weren't you supposed to be at the hospital?" said Mark.

"Um, I had a non-emergent surgery this morning and then I took off the rest of the day for personal reason," Addison could tell something was not sitting right with Mark. He never wondered if she was supposed to be at the hospital. He loved her visits. "Mark what is going on?"

Now they were standing in front of Derek's office door. "Addie, don't." She looked at Mark with a quizzical look. Then they heard it a rhythmic banging coming from the other side of the door. Addison opened the door to confirm her worst fears. "Addis-" Derek said, but at that point it was completely pointless. She was gone.

Derek just stood frozen in place, unable to move.

About an hour later he showed up at the house where he knew she would be. He stepped into the house slowly. "Addie-" he called out in the darkness. "In the kitchen," came the short reply. "Ad, I am so sorry." Derek began apologizing immediately for the affair. "How long?" Addison still hadn't met his gaze. She couldn't face him. "A couple of months." She took a moment longer before she replied, "Why, Derek?" she said quite firmly. She had finally found her back bone and looked up at him with a face of such pain and disgust that made Derek wanted to kill himself for hurting her that badly. He also noticed the obvious tear tracks on her cheeks. "I thought we were happy, Derek. I though we were trying for a baby? Have I been thinking wrong for the last couple of months?" Tears began streaming down her face again, and they had just begun to fall on his own face. "I...I...I am just so sorry, Ad." "No you don't get to use a nickname with me. You don't have that right or the right to be standing in this kitchen now. You don't get to hold me, apologize, and make it all better. Get out of my house. You can get your stuff when I'm gone tomorrow. Goodbye Derek." she said all of that with a freakish calm in her voice. After a moment she stood from the kitchen table and went into her office. She shut the door and just cried for a long while.

Now she was sitting in front of the sink bawling her eyes out. Derek had left after their conversation. She never heard the door open, but suddenly she felt arms around her. Silently she prayed that it wouldn't be Derek. When she looked up she was relieved to see that Mark was the one holding her. Suddenly she got at angry at him as well for letting Derek get away with hurting her. "Mark let me go." She had surprised him when she had spoken. "Why are you here? How could you not tell me? You knew he was screwing a nurse, and yet you didn't say a word to him or me. You and him are both cowards!" by this point she was screaming at him. Suddenly Mark just bear-hugged her, and she fought him hard. It wasn't until her strength finally gave out that she heard him whispering into her hair, "I am so sorry, Addie. I am sorry. Oh Addie forgive me. I am just sorry." She just cried in his arms for what seemed like forever. When she had calmed down some he finally spoke again. "Look Addison, Derek called me upset saying you had kicked him out, and that you were just as if not more upset than him. Then he made me promise to come over and take care of you tonight because he can't."

"How could he do it, Mark, How?" Addison was saying it as if maybe she asked just the right way her question would be answered. "I don't know Addie. I just don't know." She was just crumpled up in his arms broken. Not the Addison he was used to. Finally after holding her for awhile he gently picked her up and carried her upstairs to the bedroom. He stayed by her until she fell asleep was not very long. Then he marched back downstairs, and began cleaning out the glass of the sink along with picking up the living room, which looked like someone had ransacked it.

That is when he noticed the small gift bag. It had obviously been thrown across the room. Suddenly, he remembered seeing her carry it into the office earlier. He opened it curiously as to what was in the small package. First he found a note written in Addison's "trying hard to write pretty" handwriting. It said:

D-

Rose are red,

Violets are blue,

Here are their first pictures,

and I love you!

-A

Next he found 2 little onesies in a green color obviously picked out by Addison. Then he saw the frames they were small and held the ultrasound pictures one saying, "Twin A" and the other saying "Twin B."

Things began to quickly turn in Mark's brain, and everything began to fall into place. Why she had been so cheery when she came to the office, why she was randomly there, and why Derek told him that their weekly dinners would depend on how Addie felt. She went to tell him that they were going to be parents, instead she was greeted with a sight that would possibly scar her for life. "Derek, you big jackass." Mark stated suddenly becoming with his best friend since kindergarten.