Disclaimer: I don't own ER or any of these characters. You'll notice that I've borrowed some of the storylines from ER (I don't own these either!) – but I've adapted them to fit in with where I want the story to go.

The next chapter is based on Series 7, although Elizabeth isn't pregnant and Mark hasn't proposed to her.

Thank you to those that have already reviewed. Please keep telling me what you think!

Chapter Four – Life or Death

Set after Mark discovers his brain tumour in Series 7

Mark was sat at the kitchen table, staring at the telephone.

'Call her', he told himself. 'Just pick up the phone and call'.

"Mark? Are you ok?" Elizabeth asked from behind him.

"Hmmm?"

"You were talking to yourself," Elizabeth said, concerned.

"First sign of madness," Mark said, finally taking his eyes off the telephone. "Or a sign that I've got a tumour invading my brain."

"Mark!"

"Sorry," Mark said, sheepishly. "Are you off to work?"

"Yes. Will you be alright?" Elizabeth asked.

Mark nodded.

"Ok, I'll call you later," Elizabeth said, kissing his head before leaving. Mark watched her go.

"Nothing that experimental surgery won't fix," he said to the closed door.

A few weeks ago, Mark had discovered he had a brain tumour. His only chance of survival was an experimental type of surgery in New York, which was scheduled to take place in a few days. Now, he was trying to pluck up the courage to call Susan. It was Christmas, and six months had passed since the christening. They had kept in touch, as promised, their closeness growing, and Mark was finding it difficult to tell Susan his bad news. They had spoken recently, to wish each other a happy Christmas, but Mark had decided that was not a good time to tell her that he was dying.

Mark went to reach for the telephone, when suddenly it rang.

"Hello?"

"Hi, Mark? It's Susan."

Mark couldn't help but laugh.

"What's so funny?" Susan asked.

"I was just about to call you," Mark answered.

"Yeah? Must be my sixth sense," Susan laughed. "So, how was your Christmas?"

"Oh, um, good. Yours?" Mark stuttered, put off by her happy tone.

"Very good. I…" Susan started.

"Susan, wait!" Mark interrupted, then paused not knowing the words to say.

"Mark? Is everything ok?"

"No, it's not. I, uh, I've got something to tell you, and you're not going to like it," Mark said, quietly.

"Mark, you're scaring me," Susan said, worried.

"I haven't been well. Headaches and dizziness, and I was having some problems with my speech so I had an MRI done," Mark said.

"And?" Susan asked, nervously.

"I've got a glioblastoma multiforme in my frontal cortex."

"Oh my god," Mark heard Susan say.

"It's not all bad," Mark said, reassuringly. "There's a doctor in New York who's willing to carry out a new type of surgery. I'm having it done in a couple of days."

Susan was silent.

"Susan? Are you ok?"

"Aren't I the one who should be asking that?" Susan replied, sniffing. "How long have you known?"

"A couple of weeks," Mark replied.

"A couple of weeks? Why didn't you say anything sooner?" Susan exclaimed. "We only spoke last week!"

"I know, I'm sorry. It's not an easy thing to tell someone," Mark answered.

"No, I'm sorry," Susan apologised. "It's a lot to take in. God Mark, I'm so sorry."

"Hey, at least I get some time off work," Mark said, trying to be cheerful. "People are always trying to persuade me I need a holiday."

On the other end of the phone, Susan shook her head. It was so typical of Mark to make a joke at a time like this.

"I'm glad to hear it hasn't affected your sense of humour," Susan said. "Are they optimistic?" She almost didn't want to hear the answer.

"As much as they can be. This surgery hasn't been done much."

Susan paused. "Mark…"

"Oh no," Mark interrupted. "Let's not have this conversation."

"What conversation?"

"The one where we list all our regrets," Mark replied. "The past is the past, remember? Besides, I'm going to come out of this just fine."

"You'd better," Susan said.

"So, have you got any news for me?" Mark asked, trying to change the subject.

"Oh, I, uh…no, nothing important," Susan said, dismissively.

There was a sudden silence between them. It was difficult for either of them to know what to say next.

"Listen, I'd better go. I've got some stuff to sort before I go to New York," Mark said.

"Oh, yeah, of course," Susan said, wishing she had something more positive to say. "Take care, ok? I'll be thinking of you."

"Thanks. Bye Susan."

"Bye Mark."

As they each hung up their telephone, they both prayed to God that this was not their last conversation.

A few days later, Mark and Elizabeth travelled to New York, where a Dr Burke was waiting to carry out the surgery. They were both very nervous and their relationship felt strained. Whatever either of them said seemed to hit a nerve with the other.

On 31st December, Mark and Elizabeth made their way to the hospital. They were taken to a side room, where they waited to be collected to be taken to surgery.

"Elizabeth?" Mark said, quietly. "If something happens in there, if something goes wrong…"

"Mark, I don't want to think about that," Elizabeth interrupted.

"Please, Elizabeth, let me say this. No machines, ok? No tubes and no machines keeping my body alive. Please?"

Elizabeth nodded. She didn't dare open her mouth to try to speak, knowing that she would simply choke up and start to cry. Just then, a nurse came into the room.

"Are you ready, Dr Greene?" he asked.

"Ready as I'll ever be," Mark replied, reaching for Elizabeth's hand. She took it.

"I'll be right here, ok? I'll be with you the whole time, I promise," she said, before Mark was wheeled off.

The surgery lasted nearly six hours. Mark was kept conscious throughout the operation, so that the surgeons could keep track of the parts of the brain they were removing. Elizabeth was allowed into the theatre to sit with Mark. By the end of it, they were both exhausted.

Later on, as Mark slept, Elizabeth sat by his side, her head dropping as she struggled to stay awake. The sound of the door aroused her.

"Dr Burke?"

"Elizabeth, I just wanted you to know that the operation was a success. Mark is expected to make a full recovery," Dr Burke said.

"Oh, thank God," she cried, before the tears started to flow.

"Elizabeth?" came a voice from the bed. Mark had stirred.

"You're going to be alright, Mark," Elizabeth cried. "You're going to be just fine."

She leant across his chest and cried. Mark wept too. They had both been too scared to show how frightened they had been, and now it was over they felt relieved.

"You should go to the hotel and get some rest," Mark said later to Elizabeth. "I know you didn't sleep well last night."

"No, I don't want to leave you here alone," Elizabeth said.

"I'll be alright. All I'm going to do is sleep anyway," Mark said. "Go on, go."

"Ok, but I'll be back in a few hours, ok?" Elizabeth said, bending down and kissing him.

Once she had gone, Mark cried again. There had been so many thoughts going through his head since he had found out about the brain tumour; thoughts he had not been able to share with Elizabeth. Sometimes he thought that he and Elizabeth wouldn't still be together if he hadn't got sick. But other times he would look at her and wonder if he'd have been able to cope with the past month if she hadn't been around. He had worried about Rachel, and how she would cope if he wasn't around anymore. It was bad enough that he had missed out on watching her grow up, but to not be there at all would be so much worse, it caused his heart to ache.

Finally, he drifted off to sleep again. When he woke up, he saw a blurry figure sat by his bed. It didn't look like Elizabeth. The figure was smaller, with short blonde hair.

"Hey," the figure said. Mark recognised the voice and smiled.

"Susan! What are you doing here?" he said with a smile.

"Just checking up on you," she replied.

"And how am I doing?" he asked.

"Pretty good," Susan said.

Mark started to pull himself upwards, and Susan instinctively put her arms around him to help him.

"Thanks," Mark said, gratefully.

"How are you feeling?" Susan asked.

"Like I just had brain surgery," Mark said. "My head aches a bit."

"You want me to call the doctor?" Susan asked, concerned.

"No, it'll pass," Mark said. "You're looking really well."

Susan smiled. "I wish I could say the same. You look awful!" she joked.

"I'm glad to see you've been working on your bedside manner," Mark laughed. "How long are you in New York for?"

"This is just a passing visit. I couldn't get much time off work," Susan replied.

"You know, you could have just picked up the phone," Mark said.

"I wanted to come. I wanted to be here before you went in, but my flight was delayed. I got here just after you'd gone into surgery."

"You didn't have to," Mark said.

"I wanted to," Susan repeated. "I'm sorry I was so useless on the phone last week."

"Susan, you didn't have to come all the way to New York just because you felt bad about being upset," Mark said, although he was secretly glad that she was here.

"Hey, I got a plane for you. You could at least be a bit more pleased to see me!" Susan laughed.

"I am," Mark said. "Anyway, I thought flying didn't bother you now, after seeing the hypnotist?"

"It doesn't," Susan said, unconvincingly. Mark looked at her, raising his eyebrows.

"Ok, ok. I maybe still get a bit freaked. It's not easy concentrating on breathing as well as thinking happy thoughts when you're thousands of feet in the air!" Susan exclaimed.

Mark laughed. "Happy thoughts?"

"Yeah, you know. Babies, pretty flowers, beautiful landscapes…"

"Raindrops on roses, whiskers on kittens…" Mark interrupted.

Susan smiled. "Thoracotomies, internal cardiac massage…" she continued.

"The Bulls winning this year…"

"That's a good one," Susan laughed. Mark was laughing too.

"Hey, listen, with everything that's been going on, I haven't told you my good news," Susan said. "I'm…"

"Susan?"

Elizabeth was stood at the door, surprised to see Susan sat at Mark's bedside. Mark hadn't mentioned that she was coming.

"Hi, Elizabeth," Susan said. "How are you?"

"Oh, well, I'm ok now," Elizabeth said, coming in and sitting on the other side of the bed and leaning across to kiss Mark.

"I bet," said Susan.

"How are you feeling?" Elizabeth asked Mark.

"I'm ok. Bit tired," Mark replied.

"Oh, well, maybe we should let you get some rest," Elizabeth said, looking at Susan.

Susan took the hint. "I'd better get going. My flight's in a couple of hours and I promised Susie I'd buy her a souvenir."

"Are you sure you can't stay a bit longer?" Mark asked, disappointed that they had been interrupted.

"I should go, let you get some rest," Susan said, placing her hand on his arm. "Just take it easy, ok? I don't need a shock like this again."

Mark smiled. "Thanks for coming."

"Anytime," Susan said. She bent down and kissed him on the forehead, forgetting that Elizabeth was sat right in front of them. As she stood up, she saw Elizabeth glaring at her. Trying to ease the situation, Susan said goodbye and made a quick exit.

The next couple of months continued to be rough for Mark. He and Elizabeth were arguing over petty things, and Elizabeth constantly accused Mark of being selfish. Mark felt that after everything he had been through recently, he was entitled to put himself first, while Elizabeth argued that that was not the right attitude to have in a relationship.

Mark could not escape the nagging at work either. His colleagues had noted a change in his personality and Kerry had taken it as far as forcing him into taking competency tests. He had taken great pleasure in waving his results in her face when he had passed, although this did nothing to alter people's opinions that he had changed since the surgery.

The only person Mark felt understood how he was feeling was Susan. She would listen quietly on the phone as he listed his complaints, agreeing and disagreeing with him when he sought her opinion.

Mark was now stood in his kitchen, calling Susan to tell her his results, but he could only get through to the answer phone.

"Hi, I'm not here at the moment. Or I'm screening my calls to avoid you. Whatever, just leave a message after the tone."

Mark put down the phone, preferring to speak to her so that he could hear her reaction. Instead, he tried Doug and Carol. They had been equally supportive over the past few months.

"Hello?"

"Hey, Doug, it's Mark," he said.

"Hey buddy, how's it going?" Doug asked.

"Good. I got my competency results today," Mark said.

"And?"

"I passed, of course!" Mark answered.

"Good for you," Doug said, sounding slightly distracted.

"Is everything ok your end?" Mark asked. "Carol? And the girls?"

"Yeah, mate, they're fine," Doug said. "Listen, I can't really talk, I'm just on my way to work."

"No problem, I just wanted to let you know my results," Mark said. "And I wanted to say thanks, you know, for being such a good friend recently. You and Carol."

"Hey, what are friends for?" Doug said.

"Speaking of friends, have you heard from Susan recently? I've been trying to call her these past couple of days and all I ever do is get her answer phone."

"Oh, um, Susan? I, uh…"

Mark could hear voices in the background.

"Susan's actually here," Doug eventually said. "She came to stay for a couple of days. She wants to talk to you."

Mark waited as Doug passed across the phone to Susan. He was sure he heard Doug ask if she was sure, but the next voice he heard was Susan's.

"Hey, Mark, congratulations!" she said, somewhat half-heartedly. "You must be really happy."

"I am," Mark said. "Are you ok, you sound funny?"

"Oh, um, I'm fine. Just hungover. You know what me and Carol are like when we're together," Susan replied quickly.

"Yeah, I can imagine," Mark laughed. He paused, expecting Susan to banter with him as they usually did, but she was strangely quiet.

"So, are you staying with Doug and Carol for long?" Mark asked, unsure why it was taking so much effort to make conversation.

"Um, I'm not sure," Susan answered. "I've got some holiday to take. I haven't decided what to do with it yet."

"Well, you can always come and visit Chicago if you want. I'd be happy to put you up for a while," Mark offered.

"Oh, thanks. We'll see," Susan said, in a non-committal voice. "Look, I'd better go. Carol needs some help with the twins."

"Ok, well I'll speak to you soon," Mark said.

"Bye, Mark," Susan said, hanging up the phone before Mark could say goodbye.

It was a couple of weeks later, after this strange conversation, that Mark came home to find a rather rushed message from Susan on his answer phone.

"Hey, Mark, it's Susan. Listen, I've decided to move back to Chicago. Can't stand the heat any more! Um, I don't suppose there are any jobs going at County? I could do with you pulling a few strings for me. Call me when you get this message, I'll be at home."