Disclaimer: All creative rights belong to the creators of NCIS:LA and CBS.

Prologue

This was a defining moment.

It was a strange thought to have given the circumstances, given who he was, given he didn't believe in them. The latter was odd in itself, considering he read like a psychoanalytical case-study. He just preferred to focus on the present and ignore the ever-lengthening chain of causal links.

The actions unravelling a short distance away suddenly changed that. Callen was caught up in the whirlwind of the butterfly effect.

All because of one stranger and one action.

One finger on a trigger.

One set of bullets flying through the air.

Each of those bullets disturbing the air around them, causing vibrations, creating sound.

A sound that hit Callen's ear drum.

It took a split second to register the implication, for his brain to send an electric signal along his nerves and force his limbs into movement. It was then, as his sprinted towards the source of the noise, that he realised: this was a defining moment.

3 Months Earlier

'So the thing is...'

It sounded innocent enough. Callen should have known then and there that things were going to snowball.

'So the thing is...,' Kensi had intoned with a nervous cough, seconds after Callen had started the ignition. She tried again as her words died away. 'So I told Deeks that my flight was delayed because I knew that he had his advanced combat skills training now and that, hypothetically, he wouldn't be able to collect me from the airport. So could you maybe bear that in mind if it comes up'? She looked away as the sentence drew to its dubious conclusion. She could still feel the burn of Callen's eyes on the side of her skull.

'Oh-kay,' Callen responded slowly, testing each syllable, his eyebrow raised. For better or for worse, Kensi was like him. He knew that she wouldn't be pushed into divulging if she wasn't that way inclined. And he had a sneaky suspicion that it was that knowledge that had led to him being selected as her personal airport taxi service, rather than Deeks or Sam. He turned his eyes back to the road but was ever aware of the agitated jostling of her feet oh so close to his.

At the next set of traffic lights he chanced a not so subtle glance back over at her, and weighed up his options. Her bottom lip was curled under her teeth, and her fingers were toying insistently with a piece of hair hanging loose from her ponytail. If she was trying to act nonchalant, she was failing miserably. Whatever was going on had to be something serious, Callen was sure. If she was likely to go rogue on them any time soon, he knew that she would do a damn-sight better job of trying to conceal it from him.

That left personal issues, and Callen shuddered − not simply because the first thought that crossed his mind was the fact that Kensi had not wanted to see Deeks. Did that mean that something had happened there? he wondered, not at all happy with the mental image. Although, he admitted mentally, he supposed that it was a better option than any other of the plethora of things that had been unfairly burdening Kensi over the years.

If she had really wanted to keep everything bottled up, Callen reasoned, Kensi would have just taken a cab to work from the airport. She would have hidden her inner battles behind professional walls. She wouldn't have invited Callen into her conspiracy.

Yet she had initiated him into her little intrigue, whatever it was, despite their increasingly tentative friendship. The fact both thrilled and terrified him. Now he really could not afford to carry on with his missteps.

And so Callen decided to break the silence that had been suffocating them for far longer than the car journey.

'So what did Deeks do this time?' Callen asked jokingly. The scratchy note to his voice deprived the comment of all its wit. At least it won him a smile.

'Nothing, I just couldn't cope with his needling this morning'.

'Late night?' Callen attempted this time, giving her a quick once over as she shrugged. 'Early morning?' he tried again, forcing a smirk onto his face.

She harrumphed. 'I wish,' she countered emphatically.

They were sitting in traffic now and Kensi inwardly cursed. Their standstill was giving Callen ample opportunity to measure her every gesture with his eyes. She had always found it hardest to lie to him, out of everyone. He always saw right through her excuses and her bravado. He had always kept an eye on her, without mothering her - and that's what she needed right now. She didn't want conversation, but the comfort of understanding silence.

'You're alright though?' he asked, his words heavy in the tense air. She was about to give a token response but a sharp look from Callen punctured her words before they could be fully formed. 'It's nothing that's gonna make you go rogue on us, or anything, right?' he added verbally, pleading.

Kensi rolled her eyes and could not fight off the snarky response that arose automatically. 'Like you, you mean?' She felt bad when he turned his eyes away from her sheepishly. His tendency to isolate himself had eroded away at their friendship, despite his increasing attempts to make amends. She reached across to squeeze his shoulder, and in the back of her mind she found it vaguely ironic that it was her offering him comfort, despite her situation. 'It's just messy personal stuff, Callen. Nothing dangerous. Just...'. She sighed. 'Just messy'.

Callen nodded slowly, and for the first time since they had gotten in the car, their eyes met.

The car came to a stop outside the OSP.

He reached back to haul Kensi's larger bag over the front seat before climbing out of the car and taking a first stride towards the door of the building. Momentarily he paused to remotely lock the car door once Kensi had retrieved her other belongings. He waited for her to look up and catch his eye. 'I'm pretty good with a mop, you know,' he added softly, a wistful smile on his lips. He had already turned away and started to enter the OSP before Kensi could shout her confused answer after him.

'Huh? Why a mop?'

Hand on the door handle, Callen glanced over his shoulder. 'That's what you use to clean up messes, Kens'. The words had barely left his mouth when he stepped through the door. He didn't catch the grateful smile on Kensi's face. Nor did he see it falter as she closed her eyes and took a deep breath before preparing herself for the days ahead.