Set during 02x18 when Mark Sloan first appears. This has been edited, didn't care for the first version after reading it again.
Disclaimer: I don't own Grey's Anatomy. If I did Mark & Lexie would have had a happy ending, Owen would not have cheated on Cristina, and crap stuff would stop happening to Meredith & Derek.
He catches her arm as she walks down the empty hallway late at night and pulls her into the on call room despite her protests.
"Derek, what do you think-"
His mouth slants over hers with a bruising force, and every thought from the past few months about how it was wrong to still love him and of his wife and Mark Sloan drift away. His unyielding lips pry her mouth open and forces his tongue into her mouth. Her hands slide beneath his top caressing the muscles she'd missed these last months. His hands are in her hair pulling her tightly against him.
And she loves every minute of it.
It doesn't matter that he's married. It doesn't matter that he lied to her. It doesn't matter that she told him he that she loved him and got no response back. It doesn't matter that he chose Addison. It doesn't matter that anybody could walk in any moment. It doesn't matter that right now she is a dirty mistress like Mark Sloan said they were.
Her only thoughts are of him, how she's missed him, missed this.
As long as he keeps kissing her, everything outside of this room ceases to matter.
It's only when she feels his cold hands tugging off her top does she realise what they're doing. She pulls away from him with a sound of disgust and backs away hastily. The satisfied bliss that she normally gets after kissing Derek Shepherd is missing. The shame and disgust seeps in soon after. She can't look at him. She knows what his face will look like. The sad puppy dog eyes and the guilt written all over his face. She can't bear to see him look at her like that once again.
She's only thankful that nobody did walk in. It would be around the whole hospital by the morning and she would deserve to be called a slut. She hadn't known that Derek was married before, but this time she did. She snatches her top off the door and turns away from him as she puts it back on.
"Meredith I-"
"No."
"Can I-"
"What is wrong with you?" She doesn't give him a chance to answer. "No, what's wrong with me?"
She's Meredith Grey, daughter of world renowned surgeon Ellis Grey, and nobody lets her forget it. She'll always have her mother's shadow hanging over her. Ellis Grey didn't sleep with her secretly married boss. Ellis Grey didn't have one night stands to try and cure her broken heart. Ellis Grey wasn't a dirty mistress who had the whole hospital calling her a home wrecker or a slut. She can already imagine what her mother's reaction would have been if she'd known any of this. She'd be disappointed, angry that her daughter had let something as insignificant as emotions and a man control her.
"Nothing is wrong with you."
She scoffs, looking anywhere but at him. "Yes there is. There must be. Why else do I keep torturing myself like this?"
"Meredith-"
She spins around and looks at him for the first time. She glares at him to try and keep the self loathing tears at bay. "Stop! Just stop! I can't do this anymore!"
"Do what?" he asks in exasperation.
"This back and forth. Trying to be your friend. The lingering glances. I'm done. I'm done pretending that I don't love you. I'm trying to stay away from you, yet you ask for me as your intern, you corner me in elevators, you're always looking at me. Stop it. Stop looking at me! You're married. You chose her. You know all of this yet you dragged me in here anyway! What on earth were you thinking?"
"I'm sorry." She can tell that he means it. But that means nothing to her right now.
"You're sorry? You're sorry that this happened or sorry for cheating on your wife. Is this some kind of thing to get even with Addison? Figured that because she fucked somebody else you should have a free pass?" He flinches. "But what about me? Do you have any idea what you're doing to me? Seeing you with her breaks my heart everyday, but I left you alone. And then you drag me in here and do this! You're killing me here!"
"I'm sorry. I wasn't thinking-"
"You never think, Derek. Just like you didn't think about decking Mark Sloan-" She stops talking when all emotions disappear from his face and a hard look comes to his eyes.
She laughs in disbelief. "That's it. This is about Mark Sloan isn't it? You see him talking to me, get jealous and decide to stake your claim!" She shakes her head in disappointment, but she isn't sure who disgusts her more, herself or him. She makes for the door but he grabs her, clutching the top of her arms.
"No, Meredith. I'm sorry. I didn't intend for this to happen. But this has nothing to do with Mark!" She can feel the tears coming. "Mer, look at me. Please." He tilts her head up when she doesn't respond. His hands frame her face and she tries to ignore the tears in his own eyes. "This had nothing to do with Addison. Or Mark. I just acted on instinct. I'm sorry."She rests against him as the tears finally spill over. "Why are you doing this? Why do you keep doing this to me?" she whispers. She receives no answer.
"You're everything, Meredith." He presses his lips to hers and she lets him for a moment before she pulls away and whispers, "I can't."
"Meredith, don't do this."
She raises her hands and backs away from him until her back hit's the door. Her hand fumbles for the door handle as she says, "I'm done. You made your choice Derek, so stick to it. You can't have us both. This thing between us, is over." She gives him no chance to reply. She's out of the door before her resolve crumbles and rushes down the empty hallway before she goes back into that room and begs him to never let her go.