Nathan paced back and forth, walking a figure of eight around two trees not far from the bushes he'd hidden behind with Ava only a few hours earlier. He started to sweat despite the freezing temperature, shaking his hands at his sides constantly unless pausing to bite his nails.

He never should have let her go to Dursley, not ever. And definitely not alone. Why had he not gone with her? But he knew why. 'I'd have died,' he thought. 'So I let her die instead.' A story that sounded so similar to one from two weeks ago that he'd rewritten to keep himself sane. There was only one trouble with convincing himself it hadn't happened the way it had. He wouldn't be able to learn from it.

He would do it again.

And he did. Didn't he?

His eyes often flicked over to Ava's bag in the snow which kept falling, trying to bury it. He'd trapped it under the outer branches of the leafless bushes to keep it from blowing away, not wanting to keep hold of it himself.

Taking a few deep breaths, he assured himself that he'd be fine to go for a walk and come back later and she'd just be sat there waiting for him, like nothing had happened at all.

So he left, pushing each footstep further into the snow than necessary, hoping they'd remain enough to be followed later. He let his mind wander, fearing where it would settle if not. The biscuit in his hand shrank every few steps, the chocolate melting over his tongue and the dissolving biscuit base. A hooting in the distance caught his attention, redirecting his path. He followed the sound until it had a physical form. High up in a tree sat a small pale brown owl. 'A barn owl,' he noted, his gaze fixed.

Its head swivelled towards him and the small bird flew a little closer, perching on a much nearer branch, just as high up. Trying his luck, he moved closer, and closer still. And the owl flew away. He followed it, over mounds of snow, round bushes, under bent over trees, over tree roots, over logs and bypassing the occasional snake, hedgehog or frog that hadn't had time to go into hibernation before the snow-filled Winter had crash landed on their doorsteps and taken them victim.

Of course, he ignored the dead animals, accepting it wasn't his fault, mourning their death for less than a second and then walking around them, making sure he didn't get anything on his shoes.

Attempting to calm himself down, he whistled a tune Hazel assured him was from the happy part of his childhood. Plastering a smile over his lips, he kicked at the snow, sending the white powder flying up in a puff of flour. He tried to play over in his mind events from home, with Hazel.

He threw himself to the floor, slamming his knees into the ground, and struck his gloved fist deep into the snow, and again, crying out in anguish. The cries echoed among the trees, sending birds flying. His mind had provided him nothing. Nothing! All those memories dancing right in front of him, mocking him, yet completely invisible. He tried to grab at them, feel something. anything, from before the meteor.

He could dream up an image of them both playing cards, her celebrating her win. He could dream up an image of the two of them in the park. There were plenty more images on top of those, as well.

But he hadn't lived them, he'd created them.

And Dursley made sure he knew that.

It was hard, growing up. And harder still when a meteor crashes and flips your whole developing world upside down. And even worse when your city is known for its technological advancements, its scientific breakthroughs, and thought it necessary to send volunteers out to catch The Fist.

They sent twenty people out into the woods to catch the awful virus, trackers implanted in their forearms. Once the signal reported that movement had become erratic, they sent a team of people kitted out in full-body suits with sterilised trucks to collect the twelve surviving victims of the disease and take them to a quarantined laboratory to experiment on them, discovering what the virus attached to, what it looked like, what could be made that could destroy it but allow the host to remain intact. That's all they were. Hosts. Not humans anymore, dangerous test subjects enabling further experimental research into a cure, each separated so they didn't kill each other in the process.

Eventually, it was released that The Fist had to be spread by human contact and only affected humans. He couldn't for the life of him remember what evidence they'd found, but they'd quickly discovered that Nathan was immune.

And then the operations had started.

Nathan's parents had sold him to the scientists, having been promised he'd be the only way to find a cure. It had been torture, almost a constant supply of anaesthetic into his blood stream and needles in his arms all the time, drawing out blood, injecting chemicals in. Nothing that would harm him, they said. Nothing that would change him, just to see how he was unaffected to help the others.

But one injection, his mind went blank. All his past erased. Apart from the faces of his family, which even came with their name and relation attached. Mostly.

One day, his room blasted red, an alarm blaring in the corridor outside. Scrambling out of bed, he threw away the covers and ran to the door that punched him in the face when he got too close. It was Hazel, apologising for having swung the door into him and urging him out of his room, careful not to touch him. She'd brought some of his old clothes and a rather rounded rucksack was on her back, making her look like a turtle, he'd noted. Then they were racing down twisting corridors with pounding headaches from the glaring white then red then white again lights.

They broke out onto the streets not long before they could make out sirens speeding down the roads towards them. Sprinting, Hazel passed her brother gloves to keep him from contaminating her.

She may have only been eight years old but, at least according to her, she'd always been extremely strong, smart and mature for her age.

Finally, when they'd made it out of sight of Dursley, the sirens subdued and the people stopped chasing them. Well, most of the people. A few came charging after them, intent on finding what may have been their only hope at a cure. Not that they had The Fist, but they were scared that they might get it eventually. And it was that worry which caused them to catch it, for it was Nathan they caught it from, when they grabbed him to try to take him back to the City Of Experiments. He and Hazel had managed to escape, but not before witnessing the change in the men's eyes and the way they tore at each other hungrily.

Nathan promised Hazel she'd never have to see anything like that again, for they'd be safe, because he'd protect them. He set up a campsite beside a fallen log resting over a river and listened as Hazel sang a song of love and peace, that apparently their mother had sung to them every weekend, when she was home from work. She taught him the words and tried to teach him the tune too, though they both knew he was completely tone-deaf. She laughed at him for it often, and he loved her for that. Everyone else would have either lied, telling him he sounded amazing, or prodded him with this, that and the other.

Slowly standing, he barely took notice of the burrows he'd made in the snow with his scraped and cut-knuckled fists. His shaking legs carried him a little further before he slouched against a tree. Hazel. He remembered what had happened and he let himself be reminded of all the differences between that and the version he'd told Ava.

There had been no sick man, no wandering old soul that Hazel had tried to save. It was easier to blame everything on someone he didn't know, who didn't even exist. Especially when the truth was that he'd done it.

It had been a while and they'd both forgotten that though he was immune, Nathan was still infected. In one of their moments of forgetfulness, they'd hugged. Nothing too meaningful other than a simple loving hug between siblings and friends. A hug that meant his head had touched hers. And the virus had spread.

Nathan had remembered almost immediately, throwing Hazel back so hard that she was shaken into understanding as well.

And then the sweet shine of her emerald eyes started to fade.

And she screamed, "Run!"

Not for fear of spreading it to Nathan, but for fear of killing him, once The Fist had taken control.

He'd waited for a moment, hoping that the immunity ran through her blood as well, that the virus wouldn't steal her amazing, hopeful, caring mind away from her. But she could see the pain written all over her body in the tense way she held herself, trying with all her might to overcome the effects, to control the virus rather than the other way around. Not just in hope that she would be immune, but to become immune.

The pain rattled through her body, dropping her to the floor as it swiped away all her energy. Once more, her tired eyes found his and, using the last of her strength, she screamed, "Nathan! RUN!"

And she stood up. Refilled with strength, she burned his eyes away with her dead stone stare and she lunged at him, hands out, nails as claws, drawing blood from his forearm, and looking for more. That's when he ran. He ran like he never had before, away from his sister, from the person he'd vowed to keep safe.

He'd given her The Fist and then refused her her final wish: to not hurt him. But he hadn't run away. Not soon enough. And he'd let her hurt him.

From then on, he'd lived on the fence. Never knowing whether or not to go back to Dursley. If he went back, he could become a cure for everyone with The Fist, which most importantly included Hazel. But in going back, he'd be disregarding everything Hazel had fought for, what she had died for, giving him freedom.

To save his sister or to honour her. That was his question.

Every day he tossed the pros and cons for each side back and forth as if playing volleyball with himself, sprinting round the side of the net to suggest something new before sprinting round the other side to counter it before the ball of suggestions could hit the sand, finalising any decision.

One one hand, he couldn't go back to Dursley, because even if he saved her, she'd hate him for it.

But she'd never hate him.

But she'd remember he infected her.

She loved him, wanted him safe.

He wasn't safe at Dursley.

But he could be, after they got a cure.

They might never find a cure.

He had to try.

Was it better to play things safe?

Hazel never went with the safe option.

Everything she'd done was to get him as far away from the City Of Experiments as possible.

And so it went. Back and forth, up and down, rolling over, turning round, until he was certain he'd never come to a conclusion. Perhaps he was going insane.

At least, until he'd found someone to talk to, or rather they'd found him. Ava had helped him find himself again, to forget, however briefly, of what his life had been and come to.

Ava.

She was in Dursley still. How could he leave her to go alone? How could he not have at least run in after her when it had been so long? He had to help her, had to know she was okay. Even if he got caught doing so.

Pushing himself away from the tree behind him, he powered on down the way he'd come, following his deep trail of footprints, planting half as many as he went. Soon he was back at the row of blackberry bushes, taking the bag from the bramble and threading it over one arm as he ran in line with Dursley, eyes searching for her familiar figure. He'd find her. He had to.

The city, fading under the dying sun, began to pack away for the evening. At least they were nice enough to let the people go to sleep, have some time to recover, wash the blood from the whip wounds, and rub cream into the cuts. At least they had a chance of surviving, a chance to escape like he and Hazel had done. Though it was probably so that they could hurt and tear screams from their throats all over again the next day.

Feeling a weight growing on his shoulders again, he tried his best to ignore the suffering bodies between the hills, below him. He couldn't worry about them, not yet anyway. Instead, he shovelled snow behind him with every trainer to the ground.

He forced himself to stop running for fear he'd run straight past her. He stared out across the city that made him shiver, even when he knew it was just an image in his head. Though the image was of course one of blaring blue, red and white lights with a crushing sense of panic and urgent screams.

Seeing the city stretched out before him horrified him. But losing Ava absolutely terrified him.

Not seeing any signs of her, he ran a little further before stopping again and looking. By that point, the sky had turned, the moon kicking the sun from the sky as they changed shifts. He began to think he should wait till the morning, failing to see how anything so far away could be visible to him in the dark.

Just as he was wishing Ava hadn't taken his sleeping bag with him, cursing himself for not taking it out the rucksack earlier, a shadow caught his eye. Human-shaped and very small, the silhouette stole all of his attention immediately.

He watched as the barely visible figure climbed out a window from a house directly below him. And watched still as a lump almost half the size of the rest of them grew on their back, until it stopped, finding a place to rest comfortably, creating a shell. Nathan still couldn't really make out any distinct shape but he knew at once it couldn't be anyone else.

No one else would be brave enough to attempt escape.

Rising to his feet, he put the bag over his arm again and took off, chasing the also-sprinting shadow, not quite quick enough, the chemicals he'd had injected having destroyed his stamina, still slowly breaking down his muscle. He knew being active sped up the process, but he couldn't let anyone die, just to save himself.

Not again.

And not Ava.