"Hi! You're 501?"

He turned around at the question to see a young woman with long dark brown hair, currently pulled back in a knot at the base of her neck, standing in the open doorway of his new apartment, wearing nothing but a large sweater – clearly a man's size – that hung down to almost her knees and he saw that her toenails were painted a pink usually found only with candies.

"I am," he frowned. "And you are…"

"502," she answered with a bright smile. "I live right across the hall from you." She came into the apartment without asking for permission and looked around though he assumed that her apartment was laid out exactly the same way as his was. She spun back around to look at him. "You're not a serial killer, are you? Because this building is new and so far, you and me are the only ones on this floor and I really don't think anyone would hear me if you did try to kill me so I just want to know now if you're a serial killer. Are you?"

He felt one corner of his mouth pull in a smirk. Who was this girl? "Not at the moment," he answered, opening a cardboard box in a stack of three.

"Well, thank god for that," she smiled and he lifted his eyebrows when she made herself at home, plopping down onto the black leather couch and propping her feet up on the coffee table in front of her, the hem of the sweater inching up her bare thighs. She had incredibly pale – and very smooth looking – skin, he noticed. "I am so glad someone else moved on the fifth floor. I mean, I work all of the time but it was still slightly scary to come back to a completely deserted floor every night. Hey! I'm making lasagna tonight. Should I bring you some lasagna?"

He looked at her and she was smiling brightly, sitting up almost like an eager puppy.

"I make the best lasagna," she added, standing up.

Again, he can't help but smirk, somewhat amused with this mysterious girl. "Is that so?" He asked. "Well… a man's gotta eat."

"Yes, he does," she smiled with a firm nod. "What do you do, 501? Will you be of use to me?" He blinked at her and she laughed. "Are you a plumber for instance? If I have a clogged drain, will you be able to help me?"

"Do I look like a plumber?" He frowned.

She tilted her head from one side and then to the other, as if she was inspecting him closely. "I'm not sure. I have met some very sexy plumbers in my day."

That made him smirk. "Well, I can help you with your pipes any time you want."

It took her a moment but she recognized the innuendo and she rolled her eyes, making him grin. She moved from the couch and his eyes zeroed in on those impossibly smooth looking legs of her as she made her way into his kitchen. She opened one of the boxes on the counter and for some reason, he didn't tell her to stop. She smiled and pulled out a red mixing bowl.

"You own Tupperware," she said. "You don't seem like the kind of guy to have Tupperware. Did you go to a Tupperware party?"

"No," he frowned. "What the hell is a Tupperware party?"

She laughed, moving onto the next box, pulling apart the flaps and peeking her head in to see what that one contained. "Oh, I like this!" She pulled out a white ceramic mug with green and red stripes and held it up for him to see. "Very… Christmas-y."

"Exactly what I was going for," he replied dryly but she didn't catch onto the tone.

She put the cup down and went back to the apartment's front door. "I have to get everything ready for dinner tonight now that I'm making it for two." She smiled softly at him from over her shoulder and he couldn't help but stare. Her smile was almost hypnotizing. "As they say in Louisiana… bayou," she said and then she was gone, the doorway empty again.

He blinked, staring at the spot where she had just been standing and then he shook his head slightly. He had no idea what the hell that was.

The instant the door to the Chief's office opened and he stepped out, Derek sprang off of the wall he was leaning again.

"Well?" He instantly pounced. "Did you sign it?"

Mark smirked. "I already rented an apartment and moved in. Did you really think I wouldn't sign it?"

Derek sighed deeply and then grinned. "Oh, thank god," he laughed slightly, slapping a hand on Mark's back. "You're staying then. Really?"

"Looks that way," Mark nodded and again, Derek clapped him on the back.

"Good. Because I have a case for us. Man was in a car crash and he has a perforated ear drum you get to fix," Derek said and approaching the nurses station, he grabbed the patient's chart and handed it to him.

"501!"

Mark instantly lifted his head and saw her coming down the hallway towards him with a wide smile on her face and he couldn't help but smile in return. Her smile was infectious. It was only when she was standing directly in front of him did he notice the light blue scrubs she was wearing.

He lifted an eyebrow. "You didn't tell me you worked here."

"And you told me you were a plumber," she laughed.

"Lexie?" Derek said, having watched the scene with confusion.

She turned her head away from Mark and smiled at Derek. "Hi, Derek."

"You know Mark?"

"Mark?" She was confused for a second and then realization dawned on her face and her eyes widened. "Oh! 501! Yes, I know him."

"Lexie, huh?" Mark smirked. "I kind of like 502 better."

"Good, because I'm still calling you 501," she laughed and then her eyes caught the white lab coat he was wearing. "Dr. Mark Sloan," she recited the stitched name on the breast. "Oh! Derek's Mark! I have heard all about you."

Again, he raised an eyebrow and he looked at Derek, who was still watching the exchange with both amusement and confusion. "What have you been telling her?" Mark asked and then looked back at Lexie. "And how do you know Shep?"

"He's dating my sister," Lexie shrugged.

"You're Meredith's sister?" Mark asked, remembering the woman Derek had brought to New York three months earlier for him to meet and apparently get the best friend approval, which he must have given considering Derek and Meredith were still dating one another. "You are nothing like her."

Lexie laughed. "I thought you were a New York boy. What are you doing here?"

"I work here now."

"He just signed a contract with the Chief," Derek jumped in. "He's now head of plastics here and I'm taking him out for celebratory drinks later tonight. You should definitely come with us, Lexie. Especially since you and Mark are such good friends," he suggested and then grinned when Mark threw him a non-amused look.

"Oh, but I'm making 501 dinner tonight," Lexie said.

"What is with the numbers?" Derek asked, completely confused. "How do you two know each other already?"

"I mean…" she corrected herself and shook her head. "Of course I would love to come out tonight." She then looked at Mark. "Only if you want me there."

Mark opened his mouth to respond but he wasn't sure what to say.

"Three!" Another doctor suddenly shouted from down the hall and Lexie suppressed an eye roll but sighed heavily.

"I have to go. My resident is foaming at the mouth." She was still looking at him, searching his eyes for something, and then as if she had found what she was looking for, she nodded. "I'll save you some lasagna. Bye Derek. 501… bye you," she said and then skirting past Mark, she hurried down the hall, Mark turning to watch her.

"Ooooo-kay," Derek said, coming up beside him. "Do you want to tell me what that was all about?"

Mark shook his head slightly as he watched 502, who was apparently named Lexie, follow her resident into the elevator, the doors sliding shut behind them. "I am still trying to figure that out."

For a moment, he thought he had made the mistake in bringing someone home with him the night before because when he woke up the next morning, he felt fingers soothingly sifting through and stroking his hair. But when he opened his eyes, he wasn't lying in his bed with a strange woman next to him. Instead, he was sprawled out on his couch and it was Lexie who was sitting on the coffee table, leaning into him, stroking his hair.

"Oh, god," he groaned. "I think I'm dying."

"How much did you have to drink?" She asked softly, laughing slightly.

"I was trying to keep up with your sister," he said and she laughed again.

"Such a rookie mistake," she shook her head. "I have water, Tylenol and a trash can. What do you want first?"

"Death."

She rolled her eyes and held out the cup of water which he propped himself up on one elbow and took, gulping most of it down.

"Why didn't you come last night?" He asked, taking the two white caplets she was holding out to him. "You could have come."

"I would have gone… but I don't drink," she said.

"Never?"

"Never."

"But Derek asked you… why would he ask you if you never drink?" Mark frowned.

She smiled. "Because he doesn't know." She held up the small trash can but he shook his head before throwing tossing the Tylenols in his mouth and swallowing them down. "My dad's an alcoholic so I stay away from everything like that."

"Oh." He paused. "I'm sorry."

"Why?" She asked, tilting her head slightly to the side, staring at him.

He smirked, shrugging. "I don't know. Isn't that what people say in situations like this?"

She laughed slightly. "You really don't seem to be the kind of guy who does what most would do in situations."

"And you don't seem like that kind of girl." He raised his eyebrows, looking her up and down, noting that her hair – which was a lot longer than he thought it was – was worn down that morning with the ends in a slight curl and she was wearing nothing but panties (hopefully) and a long-sleeve tee-shirt that was clearly not hers because it was so much bigger and practically swallowing her. "Do you actually own any pants?" He asked.

"I do," she smiled. "But I like being comfortable when I'm not at the hospital and really, what am I doing right now that requires pants?"

"How did you get in here?" Mark suddenly asked, realizing that she was in his apartment.

She rolled her eyes and grabbed his keys that she had set next to her on the coffee table. "I know we're the only two people on this floor but you really shouldn't leave these in the door. That's why I came in here. I wanted to make sure you were still alive. You're welcome by the way."

"Thank you," he said and then took another gulp of water.

"I also brought some lasagna if you want some," she said.

"God, yes. I am starving." He watched as she stood up, his eyes instantly going to the exposed skin of her thighs and he couldn't help but reach out and touch her.

"Whoa," she laughed, surprised, looking down at him. "What are you doing?" She asked but he noticed that she didn't move away from his hand.

"Your skin is really soft," he observed, his fingertips sliding across her thigh, down towards her knee, his eyes fixated on what he was doing.

"And apparently, you are still drunk." She laughed once more, shaking her head and then moved away then, heading into the kitchen with the empty water glass. "You should brush your teeth. And take a shower. And change your clothes."

Mark smirked, slowly standing up, making sure not to rush since he head was still spinning. "You know, just because you randomly burst into my apartment whenever you want really doesn't give you the authority to boss me around. There's a reason I'm single."

"I'm sure there is," she smiled sweetly at him and he couldn't help but smirk to himself as he headed down the hallway to the bathroom to do as she said though he wouldn't admit that he was doing it because she told him to.

Mark stormed into the on-call room, slamming the door shut behind him and then leaning back against it, he dug the balls of his hands into his eyes in complete frustration. "Interns are complete idiots," he grumbled to himself.

Soft laughter – familiar laughter – filtered into his ears and flipping on the light switch on the wall, he saw Lexie, now squinting from the sudden light, lying on the bottom bunk.

"Well, all interns have their moments," she smiled at him. "Even me."

"Not you, 502," he said and she smiled at him, rendering him still for a moment. No matter how many times he saw that smile, it still amazed him just how beautiful it was, which was weird because a smile wasn't exactly what he first noticed when he looked at a woman. "What are you doing in here?"

"What do most people do in on-call rooms?" She asked.

"At this hospital? Apparently have a lot of sex," he said and she laughed, rolling onto her side, still facing him, tucking her arm underneath her heard and using that as a pillow instead of the one on the bed. "You taking a nap?"

"Trying to," she nodded.

He instantly flipped the light off, the room returning to darkness. "Sorry about that." He didn't leave and instead climbed up the ladder to the top bunk above her and stretched out on his back, linking his fingers behind his head and staring up at the ceiling. "You having a better day than me?" He asked.

"How is your day?" She inquired.

"Interns are idiots," he reiterated.

She was quiet for a moment and then sighed softly. "Yang hates me and I have no idea what I did to her. She is so hard on me. All of the time. She doesn't bother the other interns as much as she bothers me."

Mark rolled onto his stomach and moving his head over the edge, he looked down at her, Lexie rolling onto her back to look up at him. "Did you ever think that Yang is so hard on you because she sees that you have the most potential?"

Lexie didn't say anything to that immediately. Instead, they stared at one another, their eyes now adjusted to the darkness and then, the faintest of smiles crossed over her lips.

"I hate when you do that," she informed him, shaking her head slightly and at his quizzical expression, she smiled again. "You make me feel happy whether I want to or not."

He smirked almost bitterly at that. "Trust me. If that's true, you are the first person I have ever made happy."

It was her turn to look at him with questions in her eyes but he only shook his head before rolling back onto his back, sighing heavily. He laid there until he heard her breathing slowly even out and deepen beneath him and then slowly, he climbed back down and looked at her for a moment as she slept. Then for some reason – a reason he didn't even want to dwell on and think about – he took a blanket and covered her with it before slipping from the room.

"So what's going on with you and Lexie?" Derek asked as Mark handed him a beer bottle and then sat down next to him on the couch, the baseball game just about to start that they were going to spend the afternoon watching on Mark's 56-inch Plasma television that was absolutely a necessity in his opinion.

Mark had just taken a chug of beer and at Derek's question, he froze, looking at his best friend. He remembered to swallow and he did so, almost choking. "Why would you ask that? Did she say something's going on?"

Derek couldn't help but smile at Mark's deer-in-the-headlights expression. "Because I always see you together at the hospital. And you have nicknames for each other."

That made Mark roll his eyes and visibly regret. "Calling each other by our apartment numbers aren't really nicknames, Shep."

"Maybe not but something is definitely going on with you two," Derek smiled, highly amused at how uncomfortable Mark was becoming. "You seem comfortable with her. Have you ever been comfortable with a woman you haven't been screwing?"

"Sure. Your mom," Mark smirked and Derek rolled his eyes. "Trust me, Derek. There is absolutely nothing going on with me and Lexie Grey."

"Mark!" The apartment door swung open and Lexie rushed in, this time in nothing but boy shorts and one of her tank tops. Derek quickly adverted his eyes but Mark hardly blinked at her attire. It was the beginning days of summer and already, he was used to seeing her wearing that type of outfit. "Please tell me you have an extra toothbrush. I just dropped mine into the toilet and I am running late for rounds and I can't go without brushing my teeth!"

"Just use mine," he shrugged.

Lexie hesitated and then shook her head, scrunching her nose up. "That's disgusting," she said. "Who knows what kind of cooties you have."

"Cooties?" Mark smirked with amusement. "No wonder Yang is so hard on you. Who under the age of six uses that word?"

He laughed when Lexie leaned over and punched him in the arm though it didn't even make him flinch and then with an exasperated sigh, Lexie turned and hurried down the hallway towards his bathroom.

"I'm using your toothbrush!" She called back to him over her shoulder and seconds later, she came rushing through again towards the door, blue toothbrush firmly in hand. "Hi, Derek. Bye Derek." And then she smiled at Mark over her shoulder. "Bye you."

And then she was gone and Mark smiled to himself before he realized that Derek was watching him. He then quickly took a swig of beer and pretended to focus on the game that had just started.

Derek smiled, shaking his head. "Oh, no. There's nothing going on there at all."

Mark stared at her, crossing his arms over his chest, refusing to budge from his spot by the counter that separated that kitchen from the living room. "I don't dance," he told her.

Lexie rolled her eyes. "Well, I do when I have had a crappy day and guess what? Really crappy day today!"

"So dance in your own apartment," he said though he knew she wouldn't and deep down, somewhere he wasn't ready to explore yet, he didn't want her to leave.

She ignored him and turning to his stereo, she began seeking through radio stations, smiling when she heard "(If You're Wondering if I Want You to) I Want You To" by Weezer playing. Instantly, she turned the volume knob up and Mark watched her as she began to dance around his living room in nothing but a pair of short – the shortest he had ever seen – plaid boxers and a tight tank top, her hair whipping as she spun herself around, dancing and losing herself to the music.

Mark couldn't stop watching her and slowly, he began to listen to the lyrics as well.

Then I said, "Girl!
If you're wondering if I want you to,
I want you to!
So make a move!
'Cause I ain't got all night!"

He wasn't sure what it was but suddenly, he found himself standing in front of her and Lexie stopped dancing long enough to tilt her head up to look at him. Mark lifted a hand to touch her but he stopped himself before he could come in contact with her and Lexie smiled faintly, taking another step towards him. That smile of hers made something in him snap and suddenly, he grabbed her so unexpectedly, she nearly fell into his chest but then his lips were fused to hers, kissing her so hard on the mouth, he instantly caused a moan to rise from her throat and he felt her fingers tunnel through his hair before she wrapped her arms around his shoulders. She stood up on her toes and he kissed her harder, hungrier, feeling her body pressed against his.

He finally admitted to himself that he had been wanting this, her, for a while now.

They couldn't even make it to the bed and Mark took her right there up against the wall of the living room, the stereo still blasting and her moans soft in his ear. He stripped them both completely naked and then proceeded to run his hands and lips over her body, feeling her soft skin, listening to her gasps and pleas for him to fuck her, and when he did, it was hard and fast because he knew that she had been wanting it just as badly.

He kept one of her thighs hiked high against his hip as he thrust in and out deeply, Lexie moving her hips to match his speed. Her upper back was pressed against the wall, moving up and down each time he pounded her deep and her hips knocked against his. Her hands gripped his biceps, pulling him closer, opening her mouth, begging him to kiss her and he did, hard and with tongue and when she came, it was hard and loud and she called out his name for all of the fifth floor – if anyone else lived on that floor with them – to hear.

And when Mark came, all but collapsing against her as he emptied himself inside of her, he felt Lexie's arms around him, her hands running soothing circles on his sweaty back. In the back of his mind, he realized that he was probably crushing her against the wall but he couldn't seem to move and Lexie wasn't protesting.

"Derek thought there was something between us," he told her, finally catching his breath, and pulling his head back from where it had been resting in the crook of her neck, he found that she was smiling.

"Actually, the whole hospital kind of thinks that," she said, now almost laughing. "The nurses who have tried hitting on you really hate me."

Mark smirked, shaking his head. "As if any of them stood a chance."

That made her smile and her hands went to his cheeks, pulling his head back to hers for a kiss and he smiled against her lips as she moaned pleasurably at the feel of his beard scratching against her chin sensually, her back arching off the wall and her arms circling around him tightly once again.

"Lexie?"

Suddenly hearing her name from across the hallway, Lexie pulled away with a gasp.

"Oh, no!"

"Who is that?" Mark frowned because it definitely sounded like a male.

"Lexie, are you home?" A female voice asked this time followed by knocking on Lexie's apartment door.

"Oh, no!" Lexie groaned softly again and then before Mark could react, she pulled away and began to get dressed as quickly as possible, finding her clothes scattered all over the floor. "I promised some of my friends that they could come over and we would study for our intern exam together. I completely forgot." Mark stood there, still naked, still wondering what the hell had happened because one minute, he was getting hard again, wanting her again and the next, she was rushing around like the hurricane she usually was. Pressing her hands on his chest, she stood on her toes and gave him a quick kiss on his mouth before racing towards the door. "Bye you," she smiled over her shoulder at him and then, she was gone.

Lexie laughed softly, pressing flatly against the locked door and gripping his hair with her fingers as he kneeled in front of her, his mouth and lips and tongue doing the most incredible things to her between her legs. "I thought you said you hated when people had sex in the on-call rooms constantly."

"This is our first time doing this," Mark reminded her, pulling his mouth back just for a second so he could smile up at her. "And right now, we're not having sex. This is me, going down on you."

He put his mouth back on her, sucking on her slowly like a succulent peach, his hands on her ass pulling more of her to him, and in the back of his mind, as Lexie pulled on his hair so tightly, it almost hurt, Mark wondered if this meant that now, there was definitely something going on between them.

"I don't know anything about you," Mark realized one night as they laid tangled together on the floor of his kitchen because once again, the bed had seemed just too far away. His fingers slowly circled her belly button before crawling their way up her body.

Lexie smiled up at him, bending her arm back behind her head, propping it up slightly. "Do you want me to open my book for you, 501?" She teased and he smirked before lowering his head to hers, kissing her. "What do you want to know?"

"Anything." He then shrugged. "Everything," he modified and she smiled.

"And will you open your book for me, too?" She asked.

Mark paused at that and looked at her. He was a private man by nature. Already, he had been at the hospital for six months and Derek was still the only one to know anything about him. Even Lexie, who barged into his apartment nearly every single day for one thing or another didn't even know him.

"I'll show you mine if you show me yours," Lexie whispered with a teasing smile and he smirked, she lifting her hand and rubbing the scruff at his jaw. "Will you open your book for me?"

Again he hesitated but looking at her now, naked and sweaty and looking as if someone has just thoroughly fucked her – which he had. Twice. – Mark felt himself nodding his head before settling his body on top of hers again for round three, she naturally parting her legs for him.

"To any page you want," he said and she smiled as he thrust himself inside of her.

"So there is something going on between you two," Derek said with a smug smile during a surgery they had scrubbed in on together. "I knew it."

"Yeah, Shep. You're a genius," Mark said behind his mask, concentrating on the bleeding he was trying to stop.

"So what is it? Is it a relationship?" Derek continued to press and Mark stilled for a second at the question.

"I don't think so. We're having sex everywhere in my apartment if that's what you mean," Mark answered and then smirked. "Which reminds me. You might want to bring your own chair to sit in next time you come over to my place."

Derek looks at him for a moment and then shook his head slightly. "That's disgusting," he almost groaned and Mark laughed. Derek was quiet for a moment and then glancing at him, he added, "You seem happy. You haven't been happy in a long time."

Mark didn't know what to say to that because until Derek said that, he hadn't realized that he was happy. Or that he hadn't been happy. But when he scrubbed out three hours later and he saw her rushing down the hallway with a stack of charts in her hands, he couldn't help but smile.

"Hi, 501," she smiled brightly and then stopped just long enough to give him a quick kiss, surprising him – and everyone else who was around them – before she was rushing off again but not without smiling over her shoulder and saying, "Bye you," like she always did and as Mark continued on down the hallway, he realized he was still smiling.

Mark had Lexie bent over the counter in the kitchen, his hands on her hips so tightly, he was probably going to leave bruises but really, neither of them cared. He plunged in and out, hard and fast and it was almost brutal and later, he knew he would apologize for being so rough with her even though she was handling her own, pushing back towards him, begging him to go even faster.

When they are both finished, having reached their ultimate highs before crashing back down, she remains bent over the counter, panting, and he is resting his forehead between her shoulder blades, his arms wrapped tightly around her waist.

"You had a bad day," Lexie said softly, still trying to catch her breath and it was a statement, not a question, because she already knew the answer.

Nonetheless, Mark nodded his head. "I lost a patient today. Someone I shouldn't have lost," he said and he felt her slide a hand down his forearm, covering one of his hands with her own.

She didn't say she was sorry like most people would have in that situation and Mark couldn't have been more grateful for that because he knew he couldn't stand it if she apologized for something she had nothing to do with. He hated when people did that.

He squeezed his arms tighter around her and they didn't talk any more the rest of the night. It should have scared him that she knew him well enough already to know that talking was the last thing he wanted to do.

"501, I need your help," Lexie said, bursting into the apartment, holding two dresses.

"With what?" Mark asked, standing at the stove, scrambling eggs for dinner. He would have offered her some but he knew she was allergic.

"Which one should I wear for my date tonight?" She asked and held up a black dress and a red dress, not noticing that Mark had gone completely still. "I kind of like the red one but you know what they say about women in red dresses. Trouble. But the black might be too plain. What do you think?"

"You have a date tonight?" Mark finally managed to ask, his throat tight and his jaw clenched. "With who?"

She shrugged, still not noticing his sudden change in mood. "Just a guy at the hospital. I think I will wear the black one. Thanks, Mark," she said, hurrying back towards the door but not without her usual smile over the shoulder and a "Bye you."

This time though, Mark didn't smile.

He didn't understand why he was so pissed off. She was going out on a date. Why did he care? It wasn't as if they had talked about what they were. They weren't in an exclusive relationship despite what Derek seemed convinced of. If she wanted to go out with some guy then she could. She could do whatever the fuck she wanted to do. Mark didn't care.

But he knew one thing. He wasn't going to just sit home and wait for her to get back. He quickly pulled on some dark jeans and a button down shirt, getting himself ready to go out to Joe's. He knew there were plenty of women at the hospital who wanted him if the flirting he dealt with on a daily basis was any indication and damn it, he would take advantage of that tonight.

"Mark?" He heard Lexie enter the apartment but he didn't answer her. A moment later, the heels she is wearing tapping on the hardwood floor, she appeared in the doorway of the bedroom, looking at him, wearing the black dress, her hair pulled back in a simple knot at the base of her neck. "Hi," she smiled. "Are you ready to go?"

Mark frowned at her. "Don't you have a date?"

She kept smiling. "With you."

"With me?"

"Of course with you," she said, laughing slightly. "Who else would I go out with on a date?" He stood with his arms crossed over his chest, staring at her. "Okay… Why would I want to go out on a date with anyone who wasn't you?" Still though, he kept staring and she sighed. "We don't have to go out. I just thought we could because we really don't do anything except work and have sex and it might be nice. Maybe?" She added unsurely.

He shook his head slightly. "If you wanted to go out on a date, you could have just come out and said that instead of letting me think…" he sighed heavily. "You want go out on a date with me?"

Her smile came back and she nodded. "Please."

He didn't say anything. He simply took her hand in his, she instantly linking their fingers together and he led them out of the bedroom, grabbing his wallet and car keys on the way.

"I don't like games," he told her as they stood in the hallway between their two apartment doors and Lexie tilted her head up towards him, lifting her arms and wrapping them around his shoulders. In her heels, she was more at an even height with his eyes than usual. "I mean it, Lexie," he said, his hands naturally going to her hips. "No more games."

"No more games," she nodded and he brushed his lips against hers, her eyes instantly falling closed. "I promise," she murmured and then he kissed her.

Things changed but not by much. She still burst into his apartment wearing shirts too big for her and panties that he now recognized from personally taking them off of her and she danced it out in his living room whenever she had a bad day. She made him lasagna and he took her out on dates whenever she wanted to go and after Mark promised that the couch was clean and he and Lexie hadn't had sex on it, Derek started coming over again. She still gave him quick kisses in the hallways at the hospital, not caring who saw, and she gave him smiles from over her shoulders with her usual "Bye you" parting.

She still called him 501 and he still called her 502 and late at night, when they laid tangled together in his bed, the sheets wrapped around their tired, sweaty bodies like vines, she would open him up to any page she wanted and asked him a question and he always answered. And when she would fall asleep with her body sprawled across his and her soft exhales of breath warm against his neck, that was the time Mark admitted to himself that he was happy.