Title: On the Other Side

Author: Sara and Lizzie

Rating: T. We like to use language, excessive drinking and sex.

Disclaimer: As much as owning Grey's would be nice, it's merely a fantasy.

Summary: Life didnt come down on the side of the dirty mistresses, so the dirty mistresses came down with each other. Mer and Mark learn the hard way that loving the one you're with doesn't change the one you really love. Eventually MerDer and Maddison. Set after Yesterday.

But we're never gonna survive, unless we get a little crazy.

His face was so hopeful. Undaunted, not jaded, full of bright hope. It was probably what her own face had looked like a few months ago when she sat in this very bar, praying that the next person through the door would be Derek. She had been hopeful then, she was sure. But Mark, Mark had the kind of hope she wished she could still hold on to. It was pure pick me, choose me hope. He still thought she was coming. The hope hurt her, because it was a hope that had long since died for Meredith Grey.

"She won't show you know." She said, thinking that maybe if she killed his hope a little bit, she might feel a little less empty. "He's not the kind of guy you leave if you can help it."

Mark looked at her, intensity flashing in his eyes. "What if you're wrong?" he asked her. "What if just this once, life comes down on the side of the dirty mistresses?" Meredith looked him, allowing herself to hope to for just one short second. If Addison went back to Mark… she shook her head to herself and drained the contents of her glass. That was never going to happen.

"That's never going to happen. Addison and Derek? They're some kind of golden couple. I almost died, and all he could do was stand in my foyer."

"I see the way he looks at you." Mark said, gripping her should as he sipped his drink. Meredith turned her head to face him and smiled at him softly.

"I hope it's kind of like the way she looks at you." She whispered. She bit her lip and sighed. They sat in heavy silence, each nursing their drink each hoping against hope that Addison would walk through the door. Meredith thought about what she would do if Addison came, if she gave up on Derek, and came to run back to New York with Mark. She knew she would abandon all notions of pride and go crawling back to him. She needed Derek like she needed oxygen. She had been suffocating slowly without him.

Minutes passed, and neither of them spoke as they gave way to an hour, then two. Finally Mark looked over at her, an ironic smile on his face. "Wow." He said simply. "She's really not coming."

Meredith shrugged and took a sip out of her new glass, her full drink. "We can't win, Mark." She said softly. "We can't take action. If we tempted them, if we tested them, we would be the bad guys and then we wouldn't even have hope. All we can do is wait." She said, sighing.

Mark took a long swallow of scotch. "God, that's depressing." He said. Meredith smiled a little, in spite of herself. Mark shook his head. "You know what, Grey? You're absolutely right." He said. "And you're completely wrong." Meredith arched an eyebrow at his glass, and he brushed her off impatiently. "I'm not drunk. I just realized what we can do."

"I'm not sleeping with you." Meredith said. "It would kill Derek. He would… he would never.." she trailed off. Mark smirked at her.

"That, Meredith, is where you're wrong. They only way to do nothing and something at the same time is to hit them where it hurts." Meredith shook her head.

"We can't." she said decisively, although the more she thought about it, the better it sounded. Jealousy was a powerful motive.

"We can." Mark said. "Derek and Addison are over. They're just too damn noble to admit it. The only thing keeping him trying is the idea that you'll still be waiting for him when she throws in the towel. Take that away, and they'll both panic." Meredith bit her lip, lost in thought.

"We have to have something." She said slowly, working it out in her head. "Not just a one night stand, something real. Something that looks real."

"You're not going to fall in love with me, are you?" Mark asked. Meredith considered him seriously. She was hurting, she was vulnerable. She wanted Derek. She raised her eyebrows at Mark and shook her head.

"I'm not going to fall in love with you." She said, rolling her eyes.

Mark smirked. "Fair enough. Are we doing this? Taking matters into our own hands?" he asked her. She thought about the way Derek had looked at her when he told her about the last time they had kissed. She thought about the way he looked when Addison leaned in for him to kiss her cheek. She took a long swallow of her drink and slapped her hand on the bar.

"We're doing this." She decided.