The day passed in a blur. The entire ER staff were somber as they quietly got on with the business of healing patients. In a strange way, the fact that they were short staffed kept everyone busy, helping to keep their minds off Carol, and Doug's stubborn refusal to leave her side.

As Susan's shift ended, however, her stomach churned at the thought of having to go back in there and see Carol – and Doug. It would be the first time they had been alone together since they arrived at the hospital nearly fourteen hours ago. Susan's emotions were all over the place, but thankfully so far everybody had assumed it was a reaction to Carol's accident.

In reality, that was only one factor. She had found her return to work hard. It seemed that every time she went to get something, it had been moved whilst she was off. The charts were different too. She felt disorientated and out of practice, and this had shown in the trauma room; at one point, Kerry had asked her to step out, preferring to teach Carter a new procedure than to let her do it. The ER, previously her second home, where she had felt so comfortable, seemed so strange. She felt like a complete beginner, having to constantly ask people for help.

In the rare moments that she wasn't making herself look incompetent and trying to get her bearings, her mind played over the events of the previous night. How did it happen? Why? Surely, they hadn't had that much to drink. She though back over the last weeks, months, years – had she always been attracted to Doug? They had always been good friends. So had she and Mark, she reminded herself. But this was different. Recalling the look that Doug had given her earlier in the day, as Mark held her in his arms, she wondered if they would ever be friends again. Doug's entire face had changed, contorted by a mixture of sorrow and, well, rage. Yes, she had definitely seen anger in his eyes. If it all wasn't so tragic, Susan knew she would laugh at how in the space of twelve hours Doug had gone from wanting her to hating her.

And then there was Jake. If she had a dollar for every time she wished she could've just taken Jake to the park and kicked a pile of dead leaves, running and laughing, their only worry what to have for dinner, she would've been a very wealthy woman. The thought of spending sixty hours a week away from him like this filled her with dread. Now she knew exactly what Mark had sacrificed to make sure she could have as much maternity leave as she wanted.

Ah, Mark. Possibly the biggest loser in this whole sorry mess. She knew that he must have questions – why were Doug and Susan still together at four am? Why didn't they answer the phone? Why did it take them so long to get here? Why had Carol left in the first place? But the moment he greeted her, she knew that he didn't suspect a thing. He trusted her implicitly. Their entire relationship was based on his revelation at Union Station, after so many months of hidden emotions and lost opportunities to share the truth. Ever since that day, they had vowed that their relationship would be based on truth – no more lies, no more fear of rejection. They would be honest at all times, because they loved each other.

Susan realized that she had been standing at her locker for several minutes, mulling things over, without moving. Thankfully, nobody had entered the lounge. Suddenly snapping out her near-trance, she opened her locker to find an envelope addressed simply 'Susan'. Intrigued, she ripped it open and unfolded the piece of paper inside. She was furious with what she found, and stormed straight out of the lounge. Finding a queue at the elevator, she ran up the stairs, two at a time, heading for the ICU.

Finding Carol's side room, she burst in to find Doug asleep in a chair by her bedside, his head resting on Carol's arm.

'What the hell is this!' she demanded, throwing the paper onto the bed for him to pick up. Doug unfolded the sheet and read one word, scrawled across the page in angry red letters – WHORE. He was immediately confused.

'I know that you're angry at me, but this is way out of line, Doug. Leaving horrible notes in my locker? Don't you think I'm upset about all this too?' Susan stared at him as rubbed his eyes in an effort to fully wake up. 'Well – say something!' she demanded.

After a few moments, Doug quietly spoke.

'I don't know anything about this.' He said wearily. 'Which can only mean one of two things. Firstly, that you've been cheating on Mark with someone else' - a look of disgust crossed Susan's face at this comment - 'or, more likely, that someone knows about us'.

'You've told someone?' she asked, horrified.

'No. Have you?' he asked, equally worried.

'Well someone knows, Doug. They must've worked it out when we came in together this morning. Shit! I can't believe this is happening' Susan collapsed into a chair and sunk her head into her hands.

'Susan, calm down. All we have to do is find out who it is, and make sure that this doesn't get any further'.

'Calm down? Calm DOWN! That's easy for you to say, Doug. It isn't your marriage on the verge of crumbling, is it? I mean, if you cared so much about Carol in the first place, you would've gone after her when she left. But you had to stick around, pouring more drinks, getting me more and more drunk…'

'What! Stop lying to yourself, Susan. You wanted this as much as me. But you're the one who's supposed to be perfect, living in your perfect house with your perfect son and good old Saint Mark…'

'So that's what this whole thing was about. You couldn't stand to see Mark happy, so you thought you'd ruin it for him. Well, congratulations, Doug! You've successfully ruined all our lives. I hope you're happy!'

But Doug had stopped listening, he was looking beyond Susan, over her shoulder, and what he saw was Carol, scared and awake, looking right back at him