A/N: Sequel to 'Sin', the first in the series is 'Afterdark'. You can probably read this without those two, though.

Looking back on it now, South could clearly pinpoint the exact moment it happened. Oh, there was a build-up –frustrated words, poorly concealed impatience, a much tenser air than what they were used to. Given South's prickly-as-a-porcupine temper and Wash's habit of bringing it out with the most idiotic comments, that said a lot.

But there was one moment where everything just snapped, where nothing would go back to how it was ever again because nothing could take it back.

It had been your average night on the Mother of Invention. Those who picked the short straw with their AI had begun their nightly chorus of mad shrieks and hysterical laughter. Carolina had been gone by then, and in a few days there'd be a few more disappearances; one following a loud, violent breakdown, the other quietly fading away.

South had been in her room, of course. She heard someone jogging past her door (Montana? Massachusetts? The latter had taken on the role of an agony aunt, recently) and knew she was expected to do the same, run out of her room and head to his. But after thinking about it, really thinking about it, she just couldn't find the will to get out of bed. All she wanted to do was sink into the covers and sleep.

And then a scream rose up, overpowering the others (how many were there by now? Four? Five? It sounded like dozens) and she had to get up because it was her Wash, because he had still been her Wash then. Almost every night she would get up, journey to his room and try to keep him grounded, by her, away from Epsilon and the madness he represented.

It was exhausting work. Maine would take over every now and then, offering South some relief. Her pride didn't let him do it often, though. The two had struck up an unlikely, tentative friendship somewhere along the line, right after she'd first sent him on his way outside of Wash's room.

So South stumbled out of bed and into the hallway, feeling drained, hair a rat's nest of blonde spikes. She straightened the purple tank top she slept in and walked out of her cold, Spartan bedroom and into the arguably colder and poorly lit metal halls of the Freelancers' quarters.

The urgent speed of previous nights was gone and she moved at a sleepwalker's pace while her tired mind tried to remember what it was doing.

After an eternity, she arrived outside his room. With a push of a button he was lying there, no doors between them, huddled and trembling, flinching away from the open door. He was tangled in his sheets and his eyes were glazed, but he calmed down a little when he saw her.

"South," he whispered. Too bright blue eyes locked onto her. Just by looking, she could tell he'd had a bad night. It would take time to get him out of whatever nightmare his bastard AI had put him through. Time, energy and patience.

Two of those things she just didn't have.

South turned on her heel and walked away. Left him calling for her. Left him pleading for her. A part of her (the part Wash would later identify as his South, the part that gave him nothing but hatred for the cold, rotten bitch who'd killed her and stolen her face) told her to turn back, it wasn't too late.

But she was drained. She could barely walk. She was numb.

And when she stumbled back into her bedroom, she had to lean against the icy walls for support before she collapsed on her bed.

There was still that part of South that would always hate her for that night. The next morning, Maine had cornered her outside the cafeteria, preparing to snarl into her face before he got a good look at her. The lank hair, dark bruises under dead eyes, a ghostly complexion.

He understood. Maine never really forgave her for that night, all friendly feelings towards each other were lost forever, but he understood. And she understood that he would hate her from now on, that any attempt to approach Wash would be seen as a threat.

Agents Maine and South Dakota, both with the words 'volatile' on their official files, understood each other perfectly.

Wash didn't speak to her after that, not outside of what was required. Occasionally, she would see him cast her a pained, confused glance, trying to figure out why she'd done it or who she was now or what had changed them both so drastically.

Epsilon was the what answer, or at least part of it. He may have forced them to realise how much they meant to each other, but he'd put the weight of the world on a barely-there relationship. Maybe if they'd been together for longer… but maybe not.

South didn't know the who answer.

Thinking back on it, South figured it was just another thing about Project Freelancer. It was a hostile environment to love, or even like. It was almost inevitable that she and Wash would end so badly.

And so, as Wash bled from two hits and shouted orders at her, while the man who had hated her but now probably barely recognised her shot and snarled at them, as Delta whirred and worried in her armour, pulling the trigger was far too easy.