This chapter was very rushed, unfortunately, and I do not enjoy writing confrontation. It was intended to only be the first half of a chapter, but the length got out of hand. Besides, I'm going on a trip tomorrow and wanted to get one last update in.
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In his muddled mind, Mark heard the door open. It was a distant click and bounce of the handle, something that his mind did not allow itself to fully register. Still, he heard it all the same. But he was focused solely on where his hands were on Callie's body and how his lips were mingling with hers, He couldn't bring himself to focus on anything else, even when he tried – when he did, he just remembered Kevin and why he was in this situation in the first place.

So, even after the door opened, he kept kissing Callie, unable to tear his concentration from the distraction at hand. His choice was beginning to show its true colors, starting to feel empty and inadequate. A terrible heavy feeling, possibly guilt, was manifesting itself deep in his chest. But he couldn't stop, because this awful feeling was still better than what would come with acknowledging that Kevin was dead. He just needed to put it off for as long as possible, and if he kept moving with Callie, lips parting and sighing, he would be able to.

But, then, he realized that he was kissing her on the corner of her mouth instead of full on the lips. She had twisted her head to see who the intruder was, and when Mark saw the color drain from her face and saw her eyes double in size, he made himself look.

When he did, he was hurled back into reality so violently that it actually made him dizzy. The bottom of his stomach dropped out and his mouth turned desert-dry. He tried to form her name, but he could only think it.

Lexie.

He instantly removed his hands from Callie's half-bare body and moved away from her, but it was too late. The damage had already been done. A hot and prickly sensation traveled from his cheeks to his fingertips, and then down to his legs. Dread. He had done it. He had hurt her. He swallowed. Two conflicting ideas waged war in his head. Of course he had hurt her, he was Mark Sloan. But he hadn't wanted to hurt her, he didn't want to sabotage the great thing they had. He tried to swallow again but couldn't.

It all happened so quickly, a matter of seconds, but it felt like a lifetime. He was frozen in place, impulsively running his tongue over his lips, staring at Lexie. He saw the subtle changes in her reaction: the initial sheepish and apologetic glace to the side, essential to catching someone in a compromising position on an on-call room. Then, the faint eyebrow-quirk and head-tilt of recognition. Then – Mark winced as this one happened – her mouth fell open and her eyes widened in an expression of sheer shock and hurt. She wasn't breathing, and her face had gone totally pale. Her heart was breaking, he could see it.

A whirlwind was cycling through Lexie's body, out of control. There was no way this was happening, this couldn't exist. She couldn't feel her body as she stared at Mark, dumb disbelief filling her and pricking at her eyes. She felt the beginnings of fight-or-flight in her system, heart rate and breath quickening and skin heating. Her stomach squeezed uneasily and it hurt.

Tendrils of dismay curled in Mark's core as the uncomfortable impasse persisted for what seemed like way too long. A single thought kept repeating itself in his head: he had hurt so many people this way already. First Derek, then Addison, and now Lexie. How many more would there be? How many more could there be?

Heart in his throat, he shifted his gaze to Callie. Her eyes were closed, her head was turned, and she was biting her lower lip, trying to block everything out – shame for what she had done, guilt for having been an enabler, and embarrassment and humiliation for having been caught and injuring someone else. She knew from the beginning that it would be a mistake. And she could have stopped it.

Lexie watched Mark look at Callie with an expression of something vaguely familiar to confusion on his face. The image of the two of them was emblazoned in her mind for good, and it was playing itself over and over like a bad song on repeat. Her skin burned and crawled. She had to get out of there before she broke; she could feel it coming. She couldn't stand here and look at them for any longer. Her face was scorching and her stomach was in knots. She took a tentative step, testing her wobbly knees (somehow they held) before bolting. By the time Mark looked back in her direction all he saw was a blur of light blue scrubs on the edge of the doorframe.

He snapped into action too. "Lexie!" he called after her, finally able to use his vocal cords. "Shit," he swore huskily, scrambling off of Callie and the bed. He snatched his shirt from the floor and yanked it over his head, tearing out the door and beginning to follow her. At that point, an explanation would most likely be futile. But he sure as hell was going to try. Lexie was keeping just out of reach, flitting around every corner with desperate double-steps. Mark pushed harder to reach her, realizing that she could move pretty damn fast when she was upset.

Mark finally managed to catch up with her on the bridge. Out of the corner of his eye, he could see through the enormous windows that it was only twilight. The day, which had been indescribably awful so far, was still far from ending. Lexie was so close now, striding quickly away from him with her shoulders hunched over and her eyes on the ground. "Lexie," he said firmly, out of breath, closing the gap and grabbing her arm. She tried to jerk out of his grip and keep going, and he did lose his grasp, but he recovered and caught her again, by his fingertips on the coarse fabric of her lab coat's sleeve. She was whirled around by the force of his grab against the force of her trying to get away.

"Let me go," she told him – it began as a demand, but melted into a pained whimper by the end. She struggled with him for another moment, keeping her eyes away from his face. "Just let me go!"

He held her there, moving his fingers to tightly encircle her wrist; he didn't want to hurt her, but he couldn't let her get away. She recognized that she wouldn't be able to escape at that point, and ceased her resistance. She chewed on her lip and closed her eyes, tucking her chin into her shoulder. Her heart was hammering against her ribcage, rattling so loudly in her own ears that she was sure everyone else could hear it was well. "Lexie," Mark said hoarsely, placing his other hand on her shoulder (she tried to shrug away), "listen to me-"

"No," she replied. She raised her eyes to glare at him, steeling her jaw. A chill ran from Mark's spine to the rest of his body. "You know what? No." Her voice sharpened tenfold into a tone that Mark hadn't known she was capable of. It made him cringe and he saw just how much this had wounded her.

He tried to speak despite her stiff rejection. She cut him off before he could form the first syllable. "What is this, Mark? What are you doing?" she asked incredulously, narrowing her eyes in injured confusion. She shook her head and began again on a different thought.

"I can't believe you!" she cried, finding it difficult to keep her emotions in check even with their fellow employees moving around them. Mark swallowed hard but still kept his hand steadfast around her delicate wrist. When she continued, her voice was very bitter, a defense mechanism designed to hurt him right back. "Then again, I know what your reputation was, so should I really be surprised?" She paused, even though the question wasn't mean to be answered. He stared at her, dumbfounded. "After everything, I thought you had changed. I really believed that you were turning into a new you, on your terms. But apparently, you haven't changed after all." She sighed sharply and shook her head. "Was it a lie? Was I just another notch in your bedpost that you became attached to for a while?" It had been such a sharp regression from the happiness and daring not to speak those three words to fucking Callie in an on-call room, where Lexie was sure it would have gone if she hadn't stumbled in upon them. The thought disoriented her for a moment, making her queasy.

The words cut him like tiny shards of shattered glass; small things that caused more pain than they should have.

"Why do I always have to try and see the best in people? Why do I constantly make that mistake? All it brings me in the end is shit," she spat. "You know, I wondered why Derek tried to keep you from me. I wondered why everyone had the notion that you were a bad guy. Now I'm seeing it. Maybe Derek and everyone were right about you." She knew how terrible that was to say, but she wanted to make him hurt too.

The pain was in Mark's heart, then, a hollow blow that ached in his ribs. Bringing Derek into this was uncalled for. It was the one thing she knew he wouldn't be able to argue or come back at. He could see that she was firing with every poisonous thing that she could think of, but that fact didn't take any of the edge away from her words. She was slipping away from him with every passing second and he was helpless to stop it.

"Or is it not that at all?" she went on abruptly, swiping his hand from her shoulder with disgust. "Is some self-destructive thing where you're so afraid to be happy that you wanted to sabotage it? If that's it, then it's even worse because you're not just hurting one person, you're hurting two." She gave him a pointed glare. "I'm embarrassed because I should be stronger than this, but if you did this to push me away," she said more softly than before, "it worked."

By that time, they had attracted a small crowd. Their colleagues stood around them, at an acceptable distance, trying to be inconspicuous about their curious and confused whispering.

"That wasn't it at all," Mark heard himself tell her in a voice bordering on desperate. He felt disconnected from his body, like he was watching everything fall to pieces on a television screen.

"Then what was it?" Lexie demanded. She waited exasperatedly for an answer and Mark just stared at her, opening his mouth and then closing it again. He hadn't expected her to actually let him speak.

At last, he collected his thoughts and answered. "I was hurting," he murmured, moving the slightest bit towards her (she moved the same distance away), "and Callie was there. I thought it would help me hurt less, but it didn't. I didn't want to."

Lexie scoffed. "You wouldn't have done it if you didn't want to."

"That's not true." His voice hardened as he was unable to calm a sudden swell of anger.

She ignored him and went on. "It's not even that you almost…" She swallowed her words because they would have stung on the way out. "You let her be there for you, Mark." The truth was pouring out. "You let her be there for you when I wanted to be there for you." She looked up at him, and her chestnut eyes showed such sudden sadness that it knocked what little air he had left from his lungs. "I was willing to give you whatever you needed. I wanted to help you! Even after all we've been through, were you afraid of scaring me away? Would you ever let me be there for you?"

He blinked at her, begging his mind to come up with an acceptable answer. Passable, even. "Yes-"

"I thought we had gotten past this," she said. "All the fear and issues and…I really must be an idiot. I've just made one stupid decision and after another and suffered through too many rejections since I came here. First Meredith, then Alex, then George, and then the one thing I thought wasn't going to be a failure, you. I don't think I can do this." She bit her lip, embarrassed.

Mark ran a hand through his hair, sighing deeply. "Lexie," he said dejectedly, shaking his head at her.

When Lexie made eye contact with him, all she could see was him entangled with Callie on the rickety bed, allowing her to be with him when he needed it most; the same time that he shunned her away. It was unbearable. She winced and glanced downward, speaking barely above a whisper. "God, I can barely even look at you."

Mark had nothing to say to that. He watched her closely and she avoided his gaze, mentally willing her not to leave. He was so intent that he didn't notice when she slipped her wrist out of his grasp.

"But that doesn't matter," she said in a tiny voice. "Because I'm done. I'm done," she declared, a scrap of strength finding its way into her shaky words. With one final sorrowful, pathetic, poignant look at him, she turned and, biting her lip against the intense pain of tearing herself away, began determinedly away from him. There was no goodbye, no final sting, or no sound-off line. It was simple and definitive. Done.

His feet were rooted to the ground. He tried to stop her, but all that came from him was a hoarse breath. His heart was pounding in his ears and he didn't even notice the looks that the bystanders were giving him, some sympathetic and some that made it seem like this was karmic.

She disappeared quickly down another hallway. He felt warmth leaving his face. She was gone. Another was gone. One that really mattered was gone.

Fury quickly replaced the numbness. Holding in a snarl, he tore himself from his frozen position and went back in the direction from which he had come, forcing his way through the people who had been discreetly watching them. He acknowledged none of them.

Halfway down the next hall, he found a small and dark supply closet. He ducked into it. Once inside, he clenched his jaw and stood there, shaking and seething. He had done it again; he had managed to fuck up yet another thing that he had been trying his damnedest not to. Maybe he was the idiot for thinking he wouldn't this time. What was there to stop him? Nothing. He would continue to do it and do it again, into forever.

With a wave of rage, he kicked the set of metal shelves on the wall across from him hard. His ears were deaf to the piercing metal clang and his foot was numb to the sharp pain. Plastic-packaged instruments and supplies cascaded from the shelving and littered the floor around his feet.

He couldn't stand being in his own skin.

The door opened and he whirled around to see who the intruder was. Callie stood in the doorway, hesitating for a moment, before cautiously making her way over to him. Looking at him apologetically and almost timidly, she reached out to touch his arm. Before she could make contact, he let out a hissing sigh and jerked away from her. Then, with a scathing glare at her, he stomped out of the closet and slammed the door behind him. She jumped at the loud bang, spooked by the whole situation. In the darkness, she rested her back against the wall and slid a sitting position on the floor, resting her elbows on her knees and placing her hands on her head. She stayed that way for a long time.

It all had begun on an out of control path, moments and emotions slipping through their fingers and being scattered through the air like infinitesimal grains of sand.

Neither Mark nor Lexie knew how it could get any worse from here.