"Why didn't Nikki come back with you?"

Jack paused before answering. "She just… she wanted… I don't know."

Thomas frowned. "Because I asked you to bring her home. I expected you to make sure she was safe. What's she playing at now?"

Jack kept his attention on the computer screen. He was just aware at the corner of his vision of the sudden tension in Clarissa's hands. It was this more than anything else that stopped him from snapping at Thomas. How the bloody hell should I know what she's playing at? Why do you expect me to know more about her than you do? Aren't you her manager?

He clenched his fists, breathed deeply through his nose, and lifted his head to face Thomas. "I think she just needed a break."

Thomas snorted. "I would have thought she'd had enough of travelling. Oh well, she's on sick leave until further notice, anyway. Let me know if you hear from her."

Jack leaned back in his chair, glaring at his boss as he walked back into his office.

Clarissa gave a meaningful cough and tapped on the desk to draw his attention back to the evidence she'd been talking him through. When he didn't immediately respond, she let out a gentle sigh and wheeled herself away from the desk.

Jack stared at the screen, biting his lower lip as he remembered those last hours in Mexico.

He was in the hospital foyer, having just got off the phone from rearranging the date of their return flights. Turning around, he saw Nikki walking towards him, clutching a bottle of water.

"They discharged you? Already?"

"Of course." She gave him an odd look. "Why would they keep me in? No serious injuries, and I've been treated for the hydration. I'm fine."

He looked at her strained, white face. Some kind of fine…

"OK… well, I rebooked our flights. We're going home tomorrow. I booked a room at the hotel airport – only one though, since I had assumed you'd be in overnight -."

She broke in. "But I wanted to go back to the centre, to see Luisa…"

In truth, Jack hadn't given their friend much thought during the last few hours. He had been running on adrenaline since Nikki's disappearance – still was. His emotions had run the gamut of black despair to a state of utter, delirious relief when the message had come through. One of Gustavo's friends had received a call from some local fishermen, and they had raced to the beach to find Nikki sitting in the shallows - dazed, wet, dusty, and covered in scratches, but miraculously alive.

Jack hadn't even bothered to argue with her or anyone else about what they should do; he'd rung the British embassy and informed them in no uncertain terms that as they'd been less than bloody helpful in locating a kidnapped British citizen, they could at least step up now. And they had. A helicopter had been sent and Nikki had been admitted to a private hospital for treatment within the hour.

He hadn't really cared who he'd offended at that moment and didn't much care now. It wasn't that he wasn't relieved about Luisa and her friends… but there was only so much his head could take. Keeping busy was the key. If he stopped for a single moment and tried to examine his current emotions, he didn't know whether he'd be able to cope much longer… and he needed to cope. Right now, he needed to be strong for Nikki. It was best not to even go there – not until they were safely home.

"Get her back," Thomas had said. And he would. He might have failed to find her, but he wouldn't fail in this.

At the hospital, once he'd satisfied himself that she was reasonably comfortable and getting good care, he'd got busy. First, he'd contacted Thomas, currently in transit in the USA, and they had both agreed that the pathologist might as well turn straight around instead of travelling onwards, since Jack and Nikki wouldn't be that far behind him. He'd then gone back to the centre to collect his and Nikki's belongings. There was a mood of muted celebration there – tears and laughter as families were reunited. He'd seen Luisa briefly, but she was occupied with her father and he had no time to wait. A few people had congratulated him on finding Nikki; he'd brushed them off as politely as possible before leaving again.

"Can't you ring her instead? I don't think there's time to go back."

She paused, seeming a little confused. Her appearance frightened him. She looked…blank. Absent. Actually worse than she had looked when they'd found her on the beach. There had been a few precious moments of elation, of shed tears, of shared relief to be back together. She'd even laughed and made some weak joke when he'd swept her up in his arms to carry her to the car. But now… it was as if shock had set in. Understandable, of course, but he was no psychiatrist, and he needed to get her safely home. His wish was almost a compulsion, not least because he knew he wouldn't be able to relax until they touched down at Heathrow.

He sighed. "Nikki, I'm not so sure it's a good idea to go back there. You know they probably want us to leave as quietly as possible. We're drawing too much attention. It's…" he paused, eyeing her nervously. "You know it's not over – not for them. Maybe it'll never be over, but there's nothing either of us can do about that. Please - let's just go home. We can go straight to the hotel and you can get some sleep. I've already picked up your bags."

He expected a flash of the old Nikki spirit – an insistence that she would be alright, that she wanted to see Luisa again, that he shouldn't fuss. That would have been normal, not this strange coldness.

She looked at him without quite meeting his eyes. "You're probably right."

And that was off too. Not even an attempt to argue, and she followed him almost meekly out of the hospital and into a taxi. She remained silently composed throughout an uncomfortable night at the hotel (where he took the sofa, having not had the foresight to book a second room).

He didn't get much sleep, and he didn't think she did either – the room was over-hot, the air thick with unspoken emotions, and his heart was still beating as hard as it had been just a few hours ago when she was lost to him, potentially forever. Why was it that he found it easier to talk to her over a phone during an extreme life-or-death situation than while face-to-face in safety and relative comfort? Was that always to be the nature of his friendship with Nikki – could they only ever truly connect during times of danger?

It was at Houston in transit that she had rebelled by announcing, abruptly but with the same odd detachment, that she would be flying to New York instead of continuing to London with him.

"But why? That's crazy! C'mon, be reasonable!" He grabbed her wrist, trying almost desperately to shake her out of her mood. "You need to get back home! We both do. After what you've been through… you need a proper rest."

She pulled her arm out of his grasp, but gently, as if to avoid hurting him. "I do – I do need rest… That's why I'm going to New York."

"But what -?" He stopped. It had been on the tip of his tongue to ask what there was for her in New York, but then he realised. Not what, but who.

She looked up at him, again not quite meeting his eyes. "I can't explain it – not right now. You just need to – to tell Thomas I… I'll be back when I can."

She leaned towards him and tilted her head up to kiss his cheek, as she had done so many times before, but her lips missed their target, partly because he had jerked his face away almost on instinct. He didn't know why he'd done that. She paused, and something akin to physical pain passed over her face for the briefest of moments before she turned away.

He stood and watched her go, not bothering to argue any further. What business was it of his to stop her anyway?

Jack jumped as a mug of coffee was dumped a little clumsily onto the desk in front of him. Clarissa was propped next to him, looking at the computer screen.

"I was just wondering what was so fascinating about a comparison of nicotine levels in vaping mixtures," she murmured, apparently engrossed by the spreadsheet data.

"Oh, ha ha." He locked the screen and swivelled to face her. "If you've got something to say, don't let any consideration for my feelings stop you."

"I never do. By the way, you could say thank you for the coffee, Jack."

"Thank you for the coffee Jack," he parroted, picking up the mug. In truth, he was a little touched; he knew how much she would have struggled making it. However hard she tried to minimize her disability in the workplace, there were simple tasks that could tax her strength.

She sat back in her wheelchair, eyeing him with something approaching sympathy. "I won't ask what happened. I know it hasn't been great… But where did she go? I mean, New York obviously, but specifically?"

"I don't know. That's the truth." He sighed. "She didn't say, and what business is it of mine?"

Clarissa narrowed her eyes at him and then shook her head. "And the sad thing is that you really believe that, don't you?"

"What are you on about? She's a colleague – she has a right to privacy -."

"Oh, come on, Jack!" She leaned forward a little; he stared at his boots to avoid her all-seeing eyes. "I think you're a little more than a colleague to Nikki. Or you should be. What you've been through, what we've all been through together, but particularly the two of you… She owes you a little more explanation, I think."

His head shot up at that, almost offended on Nikki's behalf. "She doesn't owe me anything!"

"Look - I'm as fond of Nikki as you – actually no, scrap that, because clearly I'm not." She smirked briefly and leaned back in her chair. "I am fond of Nikki – she's a brilliant pathologist, a supportive colleague and a good friend. I am not, however, blind to her faults. On this occasion, I can't help feeling that she's – maybe slightly - taken you for granted."

He sighed, letting his shoulders slump. "You weren't there, you don't know… What she went through – I don't think any of us could ever fully understand. Don't you see? She was in the dark, buried, completely alone…"

"Not completely alone. She had you."

He laughed, rubbing his face. "Yeah, sure, she had me. On the end of a phone, lying to her because I couldn't bear to tell her that we weren't coming. Some help I was."

Clarissa paused. "You don't actually know how much help you were. You haven't talked to her about it – have you?"

He shook his head. "No chance. I was too busy trying to get her home." And I couldn't even do that.

"Yeah…see, I know you, Jack. When you get stressed, you have to be doing something. You were probably so busy organising things that you didn't notice what was happening to Nikki."

"Well, what else was I supposed to do!"

She sighed. "I can't answer that. No outsider could." At his look of confusion, she clarified, "I mean, this is between you and Nikki, no one else. I've got my own relationship with her and so has Thomas. If one of us had been there, we might have approached her differently, but neither of us can tell you what your instinct should have been." She shrugged. "Maybe she just needed a hug."

He laughed slightly; a small, bitter huff. "I think this one goes beyond a hug, to be honest with you."

"You sure? Because I've been on the receiving end of a Jack Hodgson hug from time to time, and it's done wonders for my mood. Now, don't get cocky."

He grinned at her, feeling better despite himself. "I never do."

"But anyway… I'm concerned about you. And don't get cocky about that, either. She…it pains me to say it because she is a friend, but I don't always like what she does to you."

He frowned. "How so?"

Clarissa paused, seeming to choose her words with care. "You've changed since you met her – in many ways for the better, but… Look, all I'm saying is that the relationship you have with her – if I didn't know either of you, or I was observing you together for the first time, I would be absolutely stunned if I found out you weren't a couple."

"We're not – we've never -."

"Oh, for God's sake, I know that! You think I wouldn't be able to work it out? I know you too well! I'm only saying that if I didn't know better…. I've never seen you look at anyone the way you look at her. And, frankly, there have been times when I've felt it might be mutual, going by the way she looks at you."

"Does she?" was all he could think of to say in reply to this.

She gave him an old-fashioned look. "Come on, Jack. You're not that blind, so don't pretend you haven't noticed something. You've both been tiptoeing around this for years."

"And I suppose you think I should do something about it." He tried to keep his tone light.

She shrugged. "I can't tell you that. If you did start a relationship, part of me would be genuinely happy for you. You're very different as people, but you do seem to gel in some odd way. Part of me would be worried. There's a reason why Max and I try to avoid working together – we'd be arguing all the time. And what if it all went wrong? Could you carry on working together? But that's by the by. My real concern is that what you have now – this maybe, maybe not thing – it isn't doing you any good."

He rubbed his head again. "Ok, call me dense if you like, but you're going to have to work with me here. What exactly are you trying to say?"

She paused for a moment before saying abruptly, "How many times have you dropped something and gone running just because Nikki rang you?"

He was confused, this hadn't been what he'd expected at all. "I don't understand…"

"No really, how many times? I know how frequently you've skipped the gym, and then there was that time you bailed on dinner with us because you needed to take a pizza over to 'cheer her up' after a tough case."

"You sound almost jealous." It was a mild taunt, but he half meant it. There was something a little dark in her voice…

She paused, clearly thinking about it, and then laughed. "Yes, that's fair enough. Maybe I am jealous, just a little. Not like that, of course. But after all, I was your best friend first."

"And I hope you still know that I'd always come running if you ever needed me."

She smiled at him. "I know you would… but maybe not for quite the same reason… But how many times have you put your life on hold for her? And when? At weekends? In the middle of the night? Have you ever broken a date – not that there have been many of those lately – just because Nikki Alexander 'needed' you?"

He opened his mouth to form an indignant response, then stopped, frowning.

It was true that over the years, he and Nikki had grown closer, particularly so after Leo's death. After-work drinks had become a matter of course, unless one of them had a prior engagement. His phone was always on, day or night, and if her name flashed up on the screen, he'd answer it without a moment's hesitation. On more than one occasion, he'd switched off a pan of boiling pasta or turned off a TV programme he was enjoying, to grab his keys and wallet and head out of the door, no matter what time – and he never resented her for it.

It went both ways, though – she quite often popped over to his flat, clutching a takeaway and a bottle of wine simply because she knew he'd had an unusually tough day. It was a little unfair of Clarissa to suggest otherwise.

"When you put it like that…"

She nodded. "It doesn't sound healthy, does it? Not for either of you. Not for a colleague."

"And a friend," he pointed out, quickly.

She shook her head. "Even for a friend. That's what I meant before, when I said that you and Nikki were more than just colleagues - or friends. Ok, maybe that's how it works for the two of you, but does it make you happy? You're putting your life on hold here, Jack. You're not getting any younger."

"Well, thanks for that," he quipped.

She shook her head, wearily. "You know what I mean. Much as I hate to inflate your ego any further, I feel obliged to point out that you're not actually that bad to look at. You're solvent, you've got your own flat in central London, you're a reasonably charming person. So, where's the wife and two-point-four kids? Where's the happy home life?"

"I'm not unhappy."

"Maybe not actively so, but you're not happy either. Actually, that's not quite true – you're happy sometimes. Definitely happy - whenever you're with Nikki. But, in general, you're not – what's the word I'm thinking of? Content – that's it. You're not content."

He frowned at her. "You've really thought about this, haven't you? How long have you felt like this?"

"I don't really know… it's crept up in a way. Things around here haven't been the same since Leo, of course. It's not Thomas' fault, but you and Nikki – neither of you have really got over Leo. You worry about her, naturally." Her expression softened. "Look, you know I care about you – Max does too. And the look on your face since you came back from Mexico… You have some idea about where she's gone, don't you? Some suspicion?"

He heaved a shaky sigh before admitting quietly, "I think she's gone to see Harry Cunningham. I don't know for sure."

Clarissa was silent for so long that he looked up. Her gaze was distant, and she was nodding slightly. "Yes…that could be."

"I wish I knew what he was to her," he whispered, almost to himself.

"I'm not so sure you'd really want to know," was the wry response, but her eyes were kind.

They both jumped slightly, as Thomas came back into the room. "Panic over! She's on her way back. That was her on the phone just now." He paused, his eyes taking them in. "You OK?"

Clarissa answered for them both. "Yes, just double-checking something."

He nodded, brisk again. "Sure. Well, anyway, I've told her she's not to come back on any account, not until we have clearance from occupational health that she's fit to work. I can't begin to imagine what she's been through…"

Jack waited until the doors swished closed behind their boss. "What were you going to tell me to do? About Nikki, I mean?"

Clarissa turned her wheelchair away, business-like again. "I think you need to settle it. One way or another. I think you need to be sure of exactly what you want. If Nikki is the one – then get on with it. As soon as she's back – tell her how you really feel."

He swallowed nervously. Easier said than done. "Not sure I can do that, to be honest."

That earned him a glare. "Then maybe it's time you grew some." She relented at the look on his face. "Look, even if it hurts, surely it's better to know, one way or the other? In the highly unlikely event that she doesn't feel the same way…well, in that case, for your own sanity, you need to keep just a little more distance. I mean it, Jack. You need to look after yourself too."

It was on the tip of his tongue to say that it'd be impossible to keep his distance from Nikki, but she wheeled away quickly, with the air of someone who'd drawn a line under the subject.

His initial instinct was to ignore Clarissa's advice. She'd said it herself – this was between Nikki and himself. Neither she nor Thomas could really understand what was going on, and it wasn't their business anyway. He was used to being there whenever Nikki needed him. He didn't mind…did he?

Clarissa had made it sound as if he was some kind of adoring slave that Nikki selfishly called on whenever she had no one else to turn to…but she was wrong. She had fundamentally misunderstood the nature of their relationship - the natural give-and-take of late-night phone calls and takeaways, of anticipated needs for cups of coffee, of meaningful smiles that said so much without words, of casual touches that said I've got your back. It was different with Clarissa – their friendship had always been utterly honest and straightforward. With Nikki, so much more was left unsaid – and other people, even Clarissa, couldn't fully understand that.

And yet…

Why had she rung Thomas to say she was on the way home? He was her boss, of course, but Jack couldn't help feeling a little hurt that she hadn't at least messaged him as well.

In fact, it had to be the longest period since he'd known her with no contact between them whatsoever. Now he thought about it, how many days had passed since she'd walked away from him at the airport? Not even an "I'm in New York and I'm fine" text, just to put his mind at rest. What if she hadn't been fine, what if something had happened to her and he hadn't known? Didn't she know what it would have done to him, especially after Mexico? Didn't she care how he felt?

Was Harry Cunningham so important, so time-consuming, that she had forgotten Jack?

Perhaps Clarissa was right. He had two choices.

Either he should have it out with her - finally confess that he'd been horribly, stupidly, desperately in love with her almost since the day they met, and throw himself on her mercy. And it would be mercy too, and probably pity, because why would someone as perfect as Nikki Alexander even look at him as anything other than a friend? He couldn't kid himself – it was obvious. Harry might have left the Lyell, but when she was at her most vulnerable, it had been him that she'd gone running to.

Or he should withdraw to protect himself. He should try to move on and make a life for himself.

When his phone rang late that night and her name flashed up, he looked at the screen and found himself doing something that would have been utterly unthinkable just a few hours before.

The phone rang plaintively a few times more. He lay back on his bed and stared at the ceiling until it stopped.