Author's Note: Okay, I'm a MerDer fan writing an AdDek fanfic because on the show I want Meredith and Derek to be together, but in fanfics I sometimes like Addison and Derek together. So, I'll write a MerDer fic next and maybe keep alternating if I'm inspired enough. This is my first Grey's Anatomy fanfiction, so I don't know if it's any good, but hopefully some people will like it! I have three chapters written and a plan of where this is going, so hopefully it'll turn out well! The title is from the Carrie Underwood song, "I Just Can't Live A Lie." I'll probably post the next chapter mid-week and the third one by next weekend. Hopefully I'll have time to finish it by then and start the fourth one. I have finals over the next few weeks though, so it may take a bit longer, but I'll try not to let it take too long! I'm not sure about this fanfic at all; I don't know ifit's any good so I wasn't going to post it, but I nver have confidence in my own writing, so I decided I'd give it a try. This first chapter isn't too exciting, I guess it's kinda setting things up for the future. I have some more dramatic things planned for Addison and Derek as I go along though.Please read and review!

Disclaimer: I don't own Grey's Anatomy or any of the characters.

Addison sat on the edge of the hotel bed, staring out the window. 'What have I done?' She thought to herself.

"Hey hun, sleep well?"

"Fine," She smiled weakly. "I'm just going in the shower; I have a shift in an hour."

She went into the bathroom and shut the door.

-- Flashback --

Mark pulled up to Seattle Grace Hospital to pick up his paycheck for the job he'd done that week and was ready to head back to New York after the weekend.

While he was walking to the door he noticed a woman sitting on a bench alone looking somber and upset.

He immediately recognized her and walked over, "Mind if I sit down?"

She shrugged, still staring straight ahead.

He took a seat, "What's wrong?"

"Nothing," she replied quietly, fighting back tears, knowing that Mark wasn't the person she should be talking to.

"Come on," he coaxed. "I know you too well. Something happened."

She was tired of putting on a brave face and Mark was one of the few people who had seen her fall apart back in New York, so she figured she had nothing to lose. "Derek and I had a big fight this afternoon." She let a few tears roll down her cheeks.

"About what?"

"He was annoyed that I was talking to you earlier. I think he's afraid I'll cheat again, he still doesn't trust me. I told him I was just being civil to you and there's absolutely nothing between us."

"Isn't there?" he asked, clearly hurt.

"What?" she asked, taken aback by his response. Her sadness turned into anger.

"Come on, there's history with us."

"Yea, not good history. And Derek and I have been married for eleven years!"

"Are you going to deny your feelings for me?"

"I'm sorry Mark. I just don't have any feelings for you. I love my husband and I'm trying very hard to keep him happy and he doesn't seem to care and I don't know what to do." The tears began to sting her eyes again.

"That's just it. Derek doesn't see what a great wife he has. If he can't see it, then he doesn't deserve you. You're a New Yorker at heart, I can see you're not happy here. I'm leaving tomorrow. Meet me tonight at Joe's if you still care about us and want to start over again, back in New York."

He wiped her tears, then looked her in the eyes and walked away.

A few hours later Addison found herself walking into Joe's Bar. She didn't know why she was there; she loved Derek, not Mark, and wanted to reconcile with him. Yet she felt like she wasn't ready to go home and face him.

'A drink will take the edge off.' She reasoned. 'And it'll give me a chance to talk to Mark and explain that I just don't love him and can't go back with him. Maybe he'll stop asking me about it.'

She sat down next to Mark with the intention of telling him that she never wanted to speak to him again, but as he talked and she drank, something seemed to change.

She was lonely in Seattle, where she thought everyone hated her, and Mark was there and saying all the right things. He was comfortable and familiar. By the time he suggested that she come back to his hotel room, she was drunk and her judgment was poor. He wasn't as drunk as she was, but he would have done this even if he was sober; he loved her and wanted her back. The rest of the details were fuzzy for Addison. She vaguely remembered sleeping with Mark, without even protesting, and after that she just remembered waking up in the unfamiliar place, next to a somewhat familiar man.

--End Flashback--

She hoped he'd be gone by the time she got out of the shower, but unfortunately for her, he was still there.

"Addie, I ordered room service so we can have a nice breakfast."

"I don't have time. I already told you I have to get to the hospital," she said, annoyed.

"You have a half hour Addie."

"Stop calling me that!"

"Last night you said you loved it when I called you that. What's wrong?"

"I have to get to the hospital early to check on some patients," she replied, dismissing the question.

"Okay, how about dinner tonight then?"

She sighed. "Look, we can't do this. Last night was a mistake. I'm in love with another man and you know it. You took advantage."

"You're not really in love with him. You know that you're a true New Yorker. What are you doing in Seattle?"

"He likes it here and we're trying to make it work, so as long as he's happy then I'm trying to be happy here. You are just getting in the way…again."

"Hey, last time you came on to me. And you see the way Derek looks at her. He's not in love with you anymore. He loves her now."

"Mark, get out!' she shouted.

"What? I'm paying for this room! Besides, we belong together Addie."

"No! I'm with Derek. And I'm leaving for work. Goodbye Mark. Go back to New York and move on," she said firmly. She turned around and left the room.

"Crap!" She had reached the parking lot and realized that her car wasn't there.

Mark followed a minute later. "How nice of you to hold the elevator for me," he said sarcastically.

"No problem," she replied, no emotion in her voice.

"Come on, I'll drive you." he relented.

"You're the last person I'd want to show up with at Seattle Grace!"

"Fine. I'll drop you a block away."

"No. There's a cab, I'm taking it."

Again she walked away from him, this time headed towards the taxi. She approached the cab, only to find out that he was off-duty. Suddenly, her pager went off.

"Damnit!" she stamped her foot.

"I'm still offering that ride," Mark said, walking up behind her.

"Fine," she said through clenched teeth.

The car ride to the hospital was mostly silent, despite Mark's numerous attempts to start conversations.

Addison was distracted by her own thoughts. 'What did I do? Why did I do it? How could I do this to Derek?'

He pulled up in front of Seattle Grace Hospital.

"Thanks for the ride," she said coldly, as she got out of the car.

Derek was walking through the parking lot when he saw a familiar car. 'Mark.' He thought angrily. 'What is he stilldoing here?'

Once he got closer to the hospital, he saw that a woman was getting out of the passenger side of Mark's car. As she closed the car door he saw her red hair fall onto her shoulders. 'Addison.' He gritted his teeth. 'I can't believe her.'

Addison started walking towards the entrance when Derek crossed in front of her. "Addison." He greeted her, harshly.

"Derek…" she said, startled.

They continued to walk. "What were you doing in Mark's car?"

"I don't think that's any of your business."

She knew that he would be angry no matter what she said, and she was still annoyed at the way he acted yesterday, so she tried to avoid the question.

"So that's who you were with last night? I was sitting at home, waiting and worrying, and you were off fooling around with Mark!"

"By home you the trailer!"

"Stop changing the subject. I called all our friends, looking for you." The fight had now moved into the elevator.

The elevator beeped and stopped at the second floor. They were going to the fifth floor, so they stayed on. The doors opened and Meredith Grey stepped in.

Both of the Shepherds immediately stopped talking. Addison stared straight ahead, while Derek looked at the floor and then the wall.

'Good morning," Meredith said, unsure if she should say anything, as she could feel the tension in the elevator.

"Morning Dr. Grey," Addison replied, even-toned.

"Good morning Meredith. How are you today?" Derek asked smiling and quickly glancing at Addison

It was obvious to Addison that he was trying to make her jealous.

"Fine thanks, you?"

"Yea, I'm doing well." He glanced at Addison again, looking for some sense of regret in her eyes. He was hurt, although he didn't know exactly what happened with her and Mark, and he was determined to pretend it didn't bother him. He expressed his anger, but kept the hurt hidden.

Addison sighed as the three of them exited on the fifth floor. 'Today is going to be a long day.' she thought.