Author's Note: This was just spinning round in my head and demanding to be let out. First time writing for this show, bar some unpublished scribblings way back in the day before I even knew fanfiction was a thing. I'd love to know what you think. It was intended as a one-shot, but I'm toying with a follow-up ...

Split Second

The world can turn on its head in less than a blink.

Sometimes the signs are there, but - for a multitude of reasons, vague and unconvincing or precise and justified – sometimes those little bastarding signs just go unseen. Or unheeded.

Oh, sometimes life just hits you a real sucker-punch. That can happen, he'll admit. Either way though, you never see it coming until it's too late.

At least if you can't look back and suddenly, with the stunning and infuriating clarity of hindsight, see those goddamn signs … At least they might not haunt your dreams, or every second of your waking hell.

A split second. That was all it took.

That was all it took to shatter the world into a spiderweb of glass shards twinkling under neon lights. To bring everything grinding to a painful, shrieking halt. To rip his heart out of his fucking chest and crush it into dust.

Because, in a split second, she was gone.

And now, all the split seconds he'd had to make it right stretched out in front of him. So many seconds they could have been days, or weeks, or maybe even years. So many chances.

He should have looked for her sooner. How long … Fuck, he couldn't even bear to think it ... How long had she been alone? Hurting, scared. He'd told her not to be scared. Told her not to be scared, when he was flat-out terrified and trying to bullshit them both into buying his act.

All bravado, that was him. It was usually confidence, but not right then. Not when he could see how bad things were, from the blood all over their ambo to the fear in her tearful eyes. He'd known he was going to bust a gut to save her.

And he'd known, like she had, it was already too late.

He should have realised sooner. Replaying that moment - the intense heat, the wave of pressure that blasted them both off their feet … Had he seen her clutch her side, holding the injury that would slowly but surely sap her strength? He couldn't be sure, not now. Not with his mind hellbent on betraying him, seemingly determined to add to his pain, convincing him he had noticed and ignored the signs and never mind the fact they were running from a fucking fireball. Had he noticed though? In that split second …

In that split second, he could have saved her life.

But he'd hauled her to her feet and pushed on. Just like he'd pushed on at Mia's flat, when Ruby – conscientious, by-the-book Ruby - had urged caution. They'd stood in that bleak little place, the weight of a young woman's hopelessness pressing in on them, and he'd made a decision. Seven times he tried to make a difference and seven times he'd failed. He couldn't stand that helplessness. But, Jesus Christ, if he'd thought that was helplessness …

It was nothing compared to his best friend dying in his arms while all he could do was cry and beg her to stay. Like that ever fucking worked.

But that wasn't right either. It wasn't nothing. Even now, he couldn't bring himself to say that.

Mia wasn't nothing.

He had so badly wanted to be able to help her. But that only made it worse. Why, in that split second, had he turned his back on her then? Because in that split second, he had lost them both.

Why?

Knowing the answer didn't make it any easier to reconcile himself with it.

And he did know why. That call. That familiar address. That dawning realisation. Alicia was his friend and she was hurt. Physically hurt. He could fix that. He could help her. He'd chosen the easy option and now he had to live with that. It was more than Mia or Sam could fucking do. Because of him.

Because of his split second choice.

And, Christ, if he wanted to torture himself, he didn't have to stop there. Oh no, it all came crashing in on him in wave after relentless wave and he knew he'd had so many chances to set another path for any or all of them. He could even take it right back to fucking Afghanistan, when he should have pushed away the married medic and never gotten involved in the first place – or pulled her closer and never let her leave his side again.

How could he have ever let her walk away? Another split second screw-up he would forever regret, even if he'd known it would take a tougher man than him to make Sam Nicholls do anything she didn't want.

But, however much he'd tried to play it like he'd moved on … However much he'd tried to convince himself and everyone else, including her …

He loved her.

He fucking loved her like he'd never loved anyone and that had never changed. Not even for a split second.

She was strong and smart and damn near fearless, and a right gobby cow sometimes, and easily the most beautiful thing he'd ever seen. Even in her desert fatigues, with the dust of warn-torn Helmand still on her face. But especially curled up in his bed, soft skin next to his and her silky hair strewn over the pillows.

That was how she should be. Warm, vibrant, messing with his bloody head even. Just not breaking his heart. Not cold and pale and breaking his fucking heart into irreparable pieces.

Because he would give anything for one more second.

One more chance.

But the only second he had was right now, as all of that threatened to crush him under its weight.

One agonising second to consider all he'd had and stood to lose. One blood-soaked second frozen in the doorway of the emergency department, where he'd somehow staggered with her lifeless body in his arms.

One second that felt like an eternity.

Her name rippling round the room in shocked gasps and strangely hushed cries of horror broke the spell.

"I need some fucking help here," Iain Dean roared desperately at their stricken colleagues. "NOW!"

And then the world seemed to flip from slow motion to fast-forward as their team was spurred into action and moved to race one of their own into resus.

Because a split second might just be enough.