Author's Note: I downgraded the rating for now, because the R rating doesn't kick in until the last chapter.

The warning for heavy discussion of the afterlife and ghosts, discussion of canonical character death stays intact.

Mark popped one of Callie and Arizona's frozen casseroles into the oven one night; he paced circles around the kitchen as it cooked. He had almost put everything from the strange nocturnal visit out of his head. Almost a week had passed with no further incident, to the best of his knowledge. An occasional odd, unexplainable thing had happened, like his car keys being on the nightstand when he had sworn he had put them on the counter last time he went out, or the one morning when he woke up to find a fresh pair of clothing set out for him to wear. Even if he did not tend to set his clothes, nor would he have chosen the ones that were selected - although he did end up wearing them that day. Things like that. Unnerving, maybe, but nothing to lose sleep over at night.

He continued pacing back and forth. Ten more minutes.

From behind him, he heard some sort of strange noise. It almost sounded like gurgling, or as if someone was pouring something. He turned around, and gasped.

A glass bottle of Diet Coke hovered in the air above the kitchen table, pouring out brown carbonated liquid into two glasses below. Invisible hands guided the bottle with laser-guided precision. He looked closer. "Who's there?" he called out, stepping closer to the table. "Who -"

The bottle dropped and shattered into a thousand pieces on the tabletop. A shadow of a person flitted in the background.

And then - he looked again, and the faintest edge of facial features were visible on the shadow's form. He grabbed for the edge of his counter to regain his balance, because he was certain that if he did not do something soon, he would faint. He would recognize the face anywhere. Even if he lived to be a thousand years old and never saw another face again, he would recognize it without question.

"Lexie?" he called out. "Lexie! Lexie!" The form extended its arm toward him, but it dissipated into a fine mist, before it disappeared altogether, leaving him staring at a blank wall across the room. Tears flowed down his face. "Lexie! Come back! Please! Lexie!"

Of course it was her. It could never be anyone but her. If he had thought that his strange nocturnal visitor could have been anyone else, he would be deluding himself. If only it could be just a delusion. Then he could stop the worrying and wondering about what it was that Lexie wanted out of him.

After all, why else would she be haunting him?

"He saw me!" Lexie said, throwing herself against the ground and pounding her fists against the dirt. "He saw me, and he called out my name, and I couldn't do anything! George, why have you let me visit him all these times? I'm only going to make his grieving process even worse. Why do I even bother?"

"Because," George said. He rubbed large circles with the flat palm of his hand on her back and tried to comfort her. "Because you want to see him. You want to know that he's surviving day to day without you, and that time will march on eventually, despite the fact that he loves you and you obviously love him."

"He's miserable, George. He barely leaves his apartment, and Callie and Arizona have to bring him frozen dinners for him to stockpile, like he's a new mother or an invalid or something! And I feel so responsible for that. I should have been able to find it in me to live. He's not the same Mark, and I'm the reason why."

"Mark was always somewhat nicer when you were a major part of his life," George stated. "If he's not the same Mark as he once was, it's because you changed him for the better. I promise you that." He paused for a moment, the full impact of Lexie's words sinking in. "Wait. He saw you? Like, saw you, saw you? With his eyes?"

"No, George, he saw me with his penis. Of course he saw me with his eyes! He looked straight at me, and he called out my name - Lexie! - and then I was back here with you." She turned over and looked up at George's concerned face. "Why? You said it was bad, but -"

"It's bad."

"How bad?"

"Seriously bad. Like, I've heard it described as the bonds between life and death are dissolving and no one's safe, but that was some crazy guy ranting and raving, not - not anything I'd take seriously, I don't think, but - that's not good." He paused. "I'd lay low and avoid visiting Mark for now. Or anyone that you know, really. I hear Tahiti's nice this time of year?"

She grumbled and flopped back over to bury her face into the dirt. "But I don't want to go to Tahiti. Dead people can't tan. Not that I ever tanned much, but, if I was going to Tahiti, I'd want the opportunity to."

"I understand, but, just promise me, you won't visit Mark any time soon." He was not sure if he could keep the promise for himself and Izzie, but he would try. After all, there was no guarantee that just because Lexie could be seen, that he would be as well.

"I promise," she said, an acidic tone tinging her voice. "Not that I want to, but - for now."

Izzie sat on her couch and flipped through the channels. There was never much on when she wanted to sit down and watch something, but there was always a ton on whenever she was too busy or not in the mood. At last, she came upon an old black and white movie that she had watched a few times at a babysitter's, but never since she was a child. It was already about halfway through, so she pulled the blanket around her and settled into watching.

The heroine of the film was lifting her leg to show the hero how to hitchhike, and Izzie found herself enraptured. It was so easy for her to lose herself in movies, when she let herself relax like that.

Out of the corner of her eye, she saw a flash of movement. She ignored it at first. It was a trick of the eye. That was what it had to be. Just a trick of the eye, nothing to worry about.

And then she saw someone striding across her room, walking in front of the television and continuing on past, ignoring her or the two characters talking on screen. She blinked - once, twice - and looked back. Was it -? She rubbed her eyes and looked again. It was. It was him. It was George, acting as though he was walking through a room like any normal human being would.

George was Casper. Casper was George.

And it all made so much more sense now.

Being doctors in the same hospital for a period of a few years, Izzie had seen Mark in just about every imaginable state. However, the one state she was not used to was the one that greeted her after his door swung open: his eyes were red and bloodshot, and he was wearing a beat-up old rag of a U-Mass t-shirt and ratty sweatpants. "Can I come in?" she asked, running her fingers through her hair. She was anxious and nervous, not knowing for sure how he would react to her visit. At his nod, she took that as the closest thing to an acquiescence as she was going to get and she walked on in, settling down on the couch; he took the easy chair, and looked over at her.

"What are you doing here?"

It was a question that she still was unsure on how to answer, regardless of how many different answers she had run over through her head on the drive between Tacoma and here. What answer could be given with any sort of satisfaction? It was not as though she had come back calling when that mass shooting happened, and it was not like she had ever been that close to Mark - or Lexie, for that matter. "I - I thought I would say I'm sorry. In person, I mean. You were - you were dating Lexie, weren't you?"

"No." His initial answer was brief and succinct, and he rocked back into the chair. Pressing the tips of his fingers together and bowing his forehead to touch them, he continued. "I wish - You didn't answer my question. What are you doing here? None of us have heard from you in years and now, after all this time, you come to my place to tell me you're sorry about - about Lexie. And that happened months ago." His eyes flashed in anger for a moment before settling to the dull dusk that they had been.

"When George died," she started, choosing her words with an even and slow temperament, as she closed her eyes and lost herself in the memories of the time, "I - I lost someone important to me too. And not everyone thought about my reaction as such, and I've debated on if I wanted to get in contact with you and how -"

"You and O'Malley were friends, weren't you?"

"Best friends, from practically the first day we started at Seattle Grace." She hesitated before continuing. When her and George were together, the people who knew had not reacted well, and she knew that Mark and Callie were very close and tight-knit. Their friendship was by no means a well-kept secret, although not much was in the water cooler environment of their hospital. He may or may not have had pre-conceived notions about what went on between them. This was heightened with more potential negative emotions in regards to how it affected Callie in a negative manner. "We were together for a while, too."

"As in - oh. That."

"It could have been better timing, I guess. We never had good timing." She offered a tentative smile, and hoped that it was not going to lead to him kicking her out in anger. Maybe he and Callie had had a falling out. Maybe it did not matter, now that it was in the past? Callie had probably found someone new. She was dating that blonde peds surgeon when she left, after all.

"I can't agree with what happened back then between the three of you," he said, choosing his words with caution. "But I - I can't fault you for what happened either. The past is in the past, and Callie is married with a kid now, so - she's moved on. You can too."

Izzie breathed a sigh of relief. "Oh my gosh, thank you. You don't know how much that means for me to hear it - especially coming from her best friend."

"You still haven't explained what George's death has to do with you coming here." He exhaled a sharp breath and continued, "George's death had nothing to do with Lexie's, and if you wanted to extend a sympathy call - well, her funeral was a while ago."

"Three and a half months. It's been three and a half months," she said. "And I've spent - not every day, but quite a few of them - debating if I wanted to reach out and say anything to you, and if so, how and what to say. And then, the other day -" she paused. Her throat felt dry and parched. If Mark had no experience with what she was talking about, then he was going to think she was crazy and needed a straightjacket and a nice white room with padded walls. "Actually, uh - before I get into that -"

"Yeah?"

"Do you remember when I was dying of skin cancer?"

"I think everyone does. Your shotgun cancer wedding to Alex and you almost dying on the same day George did - those kind of left an impression. And it's not like our hospital was a dry, boring place on even the best of days."

She nodded and drummed her fingers against the side of the armrest. "One of - one of the initial symptoms that something was wrong with me was that I was having very - very powerful hallucinations. Vivid. Not only seeing, but feeling, touching -" she said, blushing at the memory, "- tasting. It was a complete sensory overload in every sense of the word."

"But what -"

"Let me finish before you start asking questions, because then it will all make more sense then. I didn't realize something was actually wrong until I ran some tests on myself, etcetera, yay, cancer diagnosis, you know most of the rest of the story from there."

"What was the point of telling the story to me, then, if I already knew most of it?"

"Because the hallucinations I told you about? They were of Denny. I - I don't remember if you know about Denny, but he was a patient that needed a heart transplant really badly - I fell in love with him in spite of everything - I cut his LVAD wire so that he would go to the top of the transplant list and he ended up dying because of what I did - and it was really screwed up and bad and, yeah, that's the basic story there."

"Okay, so what do seeing hallucinations of Denny and your subsequent brain tumor have to do with anything? Besides the fact that you have really crappy luck when it comes to falling in love with guys who don't die."

"I thought Denny was a ghost at first. I thought I was - you know - having sex with a ghost, and then it ended up being a hallucination, a product of my own body fighting against me. And it shook me to the core, Mark. I - I think Alex had a hard time trusting me after that, and I - I haven't been with anyone since I divorced Alex. I was afraid of letting myself fall for anyone and have this happen all over again."

"Is this all about your lack of a love life? Because coming to a man who is grieving for someone whom he loved more than life itself and asking him to have sex with you - or even worse, fall in love with you - by talking about your tumors is a new low in the history of lows. Like, grab a shovel and prepare to have lo mein and moo goo gai pan for lunch in Beijing tomorrow because you're about to end up in China with how far down you're going."

"No!" she shouted, almost in hysterics. "Mark, that's not what I'm saying. Not at all. I - I - I'm seeing ghosts again. And it's different this time, because it feels more real."

"Is it Denny? Are you seeing him again? Because, if you're seeing someone whose death you caused -"

"No," she said with additional emphasis. "And that's - that's why you got the capsule version of my relationship with George, because it's him. I'm seeing George again, Mark. George. He walks and acts so much like you or I that I can't believe that he's not really there, until he's not anymore. I wouldn't be surprised if I came home from being here with you and found him kicked up on my couch, resting his feet on my ottoman and reading the morning newspaper with a cup of coffee. That's how real it feels."

"How can you be sure your brain tumor has not returned, then? How is this any different than what you said you happened back then? With Denny, except now, it's with George and you're - you're not having sex with George's ghost too, are you? Because if you are -"

"Because you see her too," she whispered, placing her hand on top of his and closing her eyes. It was hard to look at him when she was about to say something that had the potential to shake his world down to the core. It was even harder, considering she was not certain with complete totality that what she was about to say was even true. "You see Lexie. That's the difference. And no, I'm not having sex with George's ghost. I'm not going down that rabbit hole again."

His eyes went blank and cold again, and he gripped the side of the easy chair with bare knuckles. "H-How did you know?" he stammered. He had not told anyone about seeing Lexie, because admitting to seeing Lexie meant getting treated with kid gloves and having discussions with the psych attendings that he did not want to have; he's Mark Sloan, damn it, and he has more pride than a group of lions. Seeing Lexie was supposed to be his dirty little secret that he did not share with anyone, let alone someone who had not been a part of his life at all in a good three years or so.

"You see Lexie. I see George. There - there has to be a pattern, or a meaning, or something. There just has to be. Things don't just happen for no reason, and I highly doubt both of us suddenly have tumors like the one that I had. Nor are we tripping on some really weird drugs."

"I love Lexie. You were married to Alex when George died."

"When I - when George and I broke up - we told each other - maybe someday, we could give us a chance again. And someday never came. Not for us."

His lips turned downward into a frown at her admission. "You know, I told Lexie - if she lived, that we could get married and have a family. Boys. Give Sofia - Callie's kid - brothers. Siblings, actually, a whole fucking family. There'd have been a girl too. She'd have been daddy's little princess." His laugh was caustic and bitter as he remembered the conversation the two of them had shared in her last moments alive. It was all he could do to stop from crying. "I would - I would have promised her anything in the world if it would have kept her alive for just that much longer."

"Mark."

"Izzie."

"We both loved someone who died."

"Love," he corrected her. It was an automatic gut instinct to still think of Lexie in the present tense. After all, his feelings about her had not changed. "I still love her." For him, it had been the first time since his last conversation with her that he had managed to say those words.

"I know," she said, because there was nothing more she could say. For Mark, the scars were so much more fresh than they were for her. Anything she could say to try to sympathize with his situation would come across as trite and stock sentimental, like the sentiments on dime store greeting cards: "deepest sympathy" or "your loved one will be missed." There would be nothing that she could do that would do anything to help in his situation. "I know. I do too." It was difficult for her to admit that she was still in love with George. All this time, and her feelings had not changed. She could remember what their problems were, and why they had broken up in the first place, but - she was able to look past it, with newfound clarity borne of time marching on. There had been something there, and they had let it go by them - she had gone and married Alex, and George died. That was all there was to it.

She walked the short distance from the couch to the easy chair and wrapped her arms around him in a tentative hug; in turn, he wrapped his arms around her and squeezed. The tears he had tried to hold at bay for the duration of their conversation spilled out, and they stained the side of her t-shirt with wet splotches as they held each other. Murmured, half-unintelligible statements poured out from both their mouths.

The flood gates of emotion had been opened, and they could never be properly closed again.

-to be continued-