Sleep didn't come to Darien that night. Thoughts, plans and schemes whirled through his over-active brain and he couldn't shut them off. Resigning himself to it, he trudged down to the Blink training centre, clad in nothing more than featureless black t-shirt, grey sweatpants and trainers. The empty hallways rang eerily with his footsteps. He knew that tucked away in monitoring offices there were plenty of station staff hard at work – a station like this never truly slept. But in order for the inhabitants to have some semblance of a normal schedule the operators – or perhaps just Smith – imposed a day and night rotation. Human beings simply need that pattern.

The duty guards of the marine garrison barely gave him a second glance as he went. Leading the most highly regarded team on the station had its advantages – pretty much everyone here knew his face. He didn't see any other operatives, though he knew plenty would be out on operations throughout the galaxy. Blink might have worked to an Earth-length day, but the rest of the galaxy didn't.

He started with a trip to the firing range. It was deserted at this time, but he checked out a training carbine from the duty master and trudged into the long, narrow chamber. A row of sectioned off cubicles ran down one long edge, facing out into the expanse where the virtual targets would appear. He selected one at random and stepped inside.

He keyed a custom programme into the system, one that would demand all of his considerable reactions and maybe help wrench his mind away from the phantoms they chased through the galaxy. Taking a deep breath, Darien raised the stock of the carbine to his shoulder and took aim. The training weapon didn't actually fire the superheated ceramic lances of the real thing, but instead was fitted with a low power burst laser. It would simulate the kickback and had a power pack instead of a bandoleer, but wouldn't waste ammunition. More importantly, it meant he couldn't damage the training centre with a wayward shot.

Not that Darien had many wayward shots.

A few seconds later a curtain in the form of a blue grid rose up in front of him, extending back to the far wall of the room. In a gentle motion he slid one foot back and bent his knees slightly. Then the targets started flashing.

A sphere of light shot across the target space, made up of coloured layers starting from yellow on the outside, to orange, to a central red core. Darien tracked it and fired in the blink of an eye. The burst laser lashed out and pierced the red centre; the target disintegrated into coloured pixels. Before the image had died another target was rushing across the space. He shot it too. The light kick of the training carbine dug into his shoulder but he barely noticed, aiming and firing a third time.

More targets whirled into existence far too fast for an average human to follow. Even the best colonial marines of the station's garrison wouldn't have been able to keep up with the deluge, but Darien's whole body was wired just a little bit differently. All Blink operatives displayed heightened reactions, and even by their standards he was quick. He twitched left, right, up and down, his full concentration centred on the targets.

After two minutes the programme ran its course and the blue targeting cube shimmered out of existence. Darien glanced at his score.

Ninety-seven percent centre hits.

Normally the number would have given him a little jolt of pride, but right now he just felt irritated. Even that rigorous test of his marksmanship had barely taken the edge off his whirling mind. The face of the man on the recording still haunted him. He wanted to have the bastard in front of him; to dig out the information about who was responsible for snatching away lives all across colonial space.

He ran the programme three more times before his eyes started to hurt from tracking so many targets for such a long time. With a snort of annoyance he returned the training carbine to its cradle and stomped out of the firing range, his body still blazing with pent up energy. He knew he needed to sleep if he was to be at his best for the coming hunt.

So he made his way through into the gymnasium where, in the day hours, Blink squads would be drilled in hand-to-hand combat, their bodies honed to be in peak physical condition to confront the challenges of their new careers. This too was a deserted space – the monitors powered down and lights dimmed. The twilight didn't bother him though.

Darien made his way over to the far wall where a series of impact barrier generators were lined. In their dormant state they looked like featureless poles of metal sticking out of the floor, but when activated they generated an ovular shield for operatives to practice against...or take out their frustrations on.

Keying in the activation sequence he donned a pair of fingerless padded gloves from one of the equipment lockers, and then cut loose on the unfortunate machine. Leaning back into a slight crouch with his back held straight, he unleashed a torrent of vicious blows into the barrier. Each time his fists were repelled and the readings on the screen behind showed the ferocious forces he was imparting.

Right then left, cross, hook and jab; he continued pounding the machine's defences until sweat was running down his cheeks and his arms ached. Still he didn't let up, focusing his mind on each strike, releasing all the fervent energy that was blazing within him. Eventually, with a final murderous spinning kick that sent the impact tracker spiking, he paused, breathing heavily. He stood there staring at the blue sheen of the barrier, feeling the air rush in and out of his lungs.

Then he heard a familiar voice.

"Couldn't sleep, huh?"

Wiping sweat from his eyes with his forearm, he turned to face the speaker. There stood Niamh, lounging against the doorway of the gymnasium, her arms folded. She was clad in her gym gear – a set of black leggings and a grey tank-top. She too wore a set of padded gloves and elbow guards, and her flame-red hair was tied back in a ponytail. Meeting his gaze, she smiled.

"What makes you think that?" Darien replied.

Her smile broadened. "C'mon, Darien, I know you well enough."

"I guess you do." He shrugged.

"You want to talk about it?"

"There's nothing to talk about. It's just this op – there's just a lot to sort through."

"There's an understatement if I ever heard one," she laughed. Then she nodded to the sparring mats in the centre of the gymnasium. "Fancy cutting loose on something that might hit you back?"

Darien raised a mischievous eyebrow. "Is there a challenge in there?"

"I'll go easy on you," she assured him, walking out onto the mats, her movements languid and almost cat-like in their elegance.

He grinned at that. The trainers only allowed limited full contact sparring – operatives were expected to rely on stealth and clever tactics far more than brute force. Still, that didn't stop a little healthy rivalry amongst those that excelled in the discipline. He knew full well that Niamh was one of the highest rated hand-to-hand specialists in the organisation.

But so was he.

He took up his position opposite her, curling down into a fighting stance, hands held up loosely in front of him. She followed suite. Then without preamble she darted forward, tossing out a sharp right-handed jab at his head. He slid to his right and blocked it, then pivoted back.

"Just checking," Niamh teased, moving back but still poised to spring. "So...want to tell me what's bothering you?" Then she jerked forward again.

Darien twisted and stepped, absorbing the quick hail of blows and lashing out with one of his own. She ducked and hopped away out of arms reach.

"Where do you want to start?" He cast out another questing swipe with his left hand that she slithered away from. "This whole mission, we've never been flying so blind for so long."

"It's more than that," she replied, accenting her statement with a quick one-two that he just barely parried aside.

"Meaning what?"

"We've had tough ops before," Niamh continued as they circled. "And I know they stick with us, but something about this one's got you riled – more than usual."

"How do you figure that?"

"You're a crappy liar, Darien." She shuffled in close, feinted with her left then jerked her right hand around in a swift arc. The blow connected squarely with his cheekbone and he leapt away, the left side of his face smarting from the impact.

"Okay," he grunted. "So maybe there is something."

"Enlighten me."

His jaw tightened. He knew what she was questing for – knew the real reason sleep was evading him. He just couldn't quite bring himself to say it. Grappling with his own thoughts, Darien lunged forward. She managed to block his combination of three quick jabs, but when she swung in retaliation he twisted his body and clamped his hands around her arm. Then he turned, shifting his weight and sending her tumbling head over heels onto the mats.

Niamh let out a gasp of surprise when she hit the ground, but she rolled with the impact, scrambling back to her feet. The smile returned to her face.

"I can do this all night," she told him. "Tell me what's bothering you."

Darien sighed heavily. "Don't give up, do you?"

"You know me better than that."

A surge of annoyance roiled through him, in large part because she was right. There was no way she would let him get out of this room without getting the information she wanted. He didn't really know what to say, but he started talking anyway.

"Fine," he snapped as they began circling each other again. "We've spent a lot of time hitting the fringes because of this mission."

"Uh-huh." She threw a couple of token, testing swipes out to keep him honest. "So what? We've worked the fringes before."

"Not like this."

"What's so different?"

"We're digging through people's homes; through their lives." He advanced, pressing forward with a series of methodical attacks, forcing her to back away. "You know what I've found?"

She slapped away a particularly violent swing, her brows furrowing with concentration. "What?"

"That everything we do, all the missions, all the ops – they haven't made a difference anywhere."

A hurt expression flashed across Niamh's face. "You can't believe that."

"Tell me I'm wrong!" He let out a savage right hook that she just barely ducked, his anger beginning to bubble over. "Nothing we've done has changed how this broken thing works. People still get left hung out to dry. Poor colonies are still getting rinsed for everything they're worth. People who weren't as lucky as you and me are still having their lives tossed down a furnace. We've changed nothing."

He accented his final, furious declaration with a barnstorming swing. Had it connected he would have flattened his second-in-command. But Niamh was ready for it.

She jumped to well inside his reach and clamped her elbow down over his arm as it swung into her, trapping him. Then she grabbed his other arm with her free hand and pulled, simultaneously kicking off from the mats and using her whole bodyweight to haul him off-balance. He teetered forward, and then started to fall. Niamh curled up, hitting the mat first but planting the soles of both her feet against his chest and flipping him head over heels.

Darien felt the breath leave his body as he crashed into the ground and before he could recover Niamh rolled backwards over him until she was sitting straddling him, her hands planted firmly against his shoulders to hold him down. Her chest heaved as she fought to regain her breath, and her biological eye shone as she glared down at him.

"Don't you dare," she said, her voice shaking with anger. "Don't you dare say we never made a difference. After everything we've been through how can you even think that?"

He didn't answer. He just lay there staring up at her, his mind racing. She eased the pressure on his shoulders and brought her voice under control as she continued.

"On Mars, we stopped those people from blowing up the atmospheric scrubbers. How many people would have died if we hadn't been there? On Titan Aquilla we kept that monster – that demon – from escaping out into the galaxy. How many people would have died if we hadn't been there?" Niamh blinked and he realised, with a pang of shock, that the girl who had always been as stable as a mountain was fighting back tears. "And Marianas – we killed the Leviathan before it could destroy everything on that planet. How many people would have died if we hadn't been there? If you hadn't been there?!"

He could feel her trembling; he could almost feel her fury and a wave of utter shame washed over him. What the hell had he been thinking?

"I..." he stuttered, unsure what to say. "I'm sorry."

"Damn right you're sorry," she laughed and a tear spilled out from her eye. "We're human, Darien. We can't fix everything overnight, but we matter. What we do matters."

In his heart he knew she was right. It had taken saying it out loud for him to realise how one-dimensional his thinking had become. No-one was denying the inequalities, the blemishes and injustices of human civilisation, but that was not the only measurement of change.

"Well," he said at last. "You asked."

She laughed, brushing the tear away from her cheek. "I suppose, technically that was my fault."

"Yeah, but thanks for doing it."

Then in a sudden motion he curled up, clamping his legs around her waist and shifting his weight to the right. Taken by surprise, she let out an involuntary yelp as he twisted and threw her onto her back. He landed on top of her, pinning her arms to the matt and trapping her in place as she squirmed. Eventually realising she couldn't get free, Niamh sighed and stopped struggling, blowing a loop of hair out of her face.

"Sneaky," she panted. "Alright, you win."

"You win, 'sir'," he teased, releasing his hold and placing his hands at either side of her head to hold himself up.

Niamh smiled. "Feel better now?"

"Yeah...yeah I do."

"Good."

Although he'd released his hold she didn't make any move away. She just lay there, her breathing slowly returning to normal. Her artificial eye gleamed in the dim light of the sparring centre – her real one looked straight at him. She pressed her lips together, taking a shuddering breath. Then she reached up, cupping the side of his face gently with one hand. He didn't try to stop her, feeling her fingers brush against his skin.

"Darien," she said. "You've always made a difference. I know it's hard to see sometimes – God knows I've felt the same – but you are worth so much more than you admit to yourself. Without you there would be a lot more bad things out there in the galaxy. Without you I wouldn't even be here today."

He felt the blood rushing to his cheeks. "Flatterer."

Taking her hand away from his face, Niamh propped herself up onto her elbows, leaving her face just inches away from his. He stared at her for a few seconds, at her ruffled fiery hair, her flushed cheeks and the thin sheath of gleaming metal that replaced one of her eyes.

Darien didn't really remember deciding to kiss her. One minute they were lying there face to face – the next his lips were touching hers. He closed his eyes; felt her surge against him with a tiny noise of contentment. Then one of her hands was moving through his hair and she pulled herself up. He slid an arm around her supple waist, lifting her off the gymnasium floor as he clung to her, his rock in the storm. Right there, right then, everything made sense again. He felt anchored, secure, able to rationalise his part in the whole mess of the universe.

When they eventually parted she had a smile on her face that could have lit up a black hole. For a minute they just stared at each other. Then she let out a short, high-pitched giggle that was so unlike her that he started laughing too.

"So," Niamh said once she'd controlled herself. "I take it this means we're kissing regulations goodbye?"

He grinned. "Looks that way."

"That's the best news I've heard all year."

"We'll need to be careful – if Smith finds out-,"

She placed a finger over his lips to silence him, her eye twinkling with amusement. "Shut up, sir."