A.N. I've been wanting to write an "Alex returns to the SAS" story for a long time in which he doesn't somehow bypass selection entirely or ace it with his (literally) unbelievable skills. And so, for Spyfest, here's just a taste of that. Sorry it's so short, but I have spent most of this week away, and I didn't want too much padding. Enjoy, review, and vote for your favourite Spyfest story!

Disclaimer: I don't even want to own Alex Rider.

Alex swayed on his feet and the hills appeared to spin around him, the grey peaks blurring into one. He shook his head to clear it and shifted his shoulders in a vain attempt to ease the ache from the 55lb Bergen rucksack he was carrying. After nineteen hours and over thirty miles of the march, everything he was carrying had become a dead weight and he had hit the bottom of his energy reserves. He wasn't sure he was going to make it.

Come on, Al. One more step.

He tried to ignore the fact that he had been telling himself the same thing constantly for the last three hours and reluctantly obeyed the voice in his head. Whilst he was fit and experienced, there was little that could help him now. The Endurance march was the final test of the first phase of SAS selection, and was designed to find only the most elite of Britain's men – and Alex, despite all he had done, was still just a boy. Sixteen years old. Of course, he hadn't told the SAS that.

He had frequently wondered, in his more pessimistic moments over the past few weeks, just why he was back here, in the Brecon Beacons, for another dose of the hell they had put him through two years ago. But whenever he asked himself that question, he was always able to answer it. The truth was, he had felt hollow in America with Sabina and her family, like he no longer fit in with ordinary civilians, even when they knew who he was. He missed the satisfaction he got from saving the world – the challenge and the feeling that he was making a difference. He was better at being a spy than he was at being a schoolboy.

These were all good reasons, and when he reached a decision he had spent a good two months obtaining a false identity that would stand up to the rigorous security checks and bypass his lack of military experience. Then he returned to England. He still didn't want to touch MI6 with a barge pole, blaming them for Jack's death, and had rather liked the idea of being part of a tight-knit unit like he had witnessed K-unit becoming. So here he was, and here he was determined to stay.

There was no unit to have his back yet, though. It was every man for himself and there was a small part of each of them that was secretly hoping that the others would fail so they would have more chance of succeeding. The DS couldn't care less how they did and gave them no encouragement, not so much as yelling at them. Alex was on his own.

His steps blurred into a hypnotic rhythm again and it became a little easier. He scraped the sides of the barrel to find a little more energy. Another hour drifted by without note. Then, quite suddenly, he cracked – hit the wall, whatever they called it – stumbling to a halt. He had walked too far. He was carrying too much. His feet were covered in blisters. All in all, he wanted to quit.

There had been many times during selection, when Alex had thought, this is madness. There were just as many when he had told himself to do it anyway. This wasn't one of those times. He could barely form a coherent thought. He was just driven, by instinct, to give it all up and go home.

It was a strange feeling. Alex was accustomed to depending on his instincts for survival, not used to having them work against him. This time he wasn't running from anything, when continuing to move could save his life. Instead, a vague memory drifted into his mind, of a case from a few years back: a young recruit that died of heatstroke. This time, he was convinced that moving could end his life.

Another man came up from behind to overtake, but paused briefly beside Alex.

"C'mon, Rogers. Never say die, right?"

Alex faintly recognised the man. They had been friendly towards each other but Alex was too exhausted to recall his name. It took him a moment as well to recognise his own alias – John Rogers, twenty years old. He had insisted on joining the army when he was seventeen and although his parents gave him permission, they weren't happy about it and they had gradually lost contact. All the correct records were there but calls to the people who were supposed to know John would be blocked or redirected to the people who had supplied Alex with the false identity. Alex received copies of any emails or post and often dictated the answers himself.

Somewhere, the words managed to stir up a bit of pride. He had done so much already, so surely he should be able to complete selection, especially with that bit of help from the other recruit. With an immense effort, he lifted a foot and moved it in front of the other. Then he did the same on the other side.

Only two miles left. Come on, Al. One more step.

Never say die. How appropriate, the philosophy that had kept him alive for so long – it might as well have been his motto.

Sure, having the luck of the devil helped, but it always seemed to desert him at the most crucial moments. There was more to being a Rider than that. There was skill, curiosity and blind determination. He needed the latter now, and he found it.

Because all the false identities in the world couldn't change that fact. He was Alex Rider, not John Rogers, and that was why he was here.

One more step.