Disclaimer: I don't own Thunderbirds.

Characters: John. Rating: T. Warnings: None

Drabble challenge from such-a-random-rambler: "John and lab rat".

John coughed, the action tearing itself from his throat so painfully he half expected to see blood come up with it. There wasn't, and a flash of disappointment filtered through his mind for a split second – maybe if there had been blood, the experiment would have stopped.

He scolded himself for that thought even as his lungs heaved out another series of coughs, each one worse than the last until he was retching air. After all, he was a Tracy. He couldn't quit, couldn't give up. John loathed being connected to his father's name, a rich pretty-boy playing in whatever field he wanted until he got bored of it and slid away to live off of fortune and fame, but in this case it was a different sort of pressure. Jeff Tracy had never given up, so John Tracy couldn't give up, either.

His arms trembled, protesting loudly at being told to support his weight as he pushed himself up, off of the ground and back into a standing position. His knees buckled, legs quivering like leaves in a breeze, and abused fingers grasped the bars to haul himself upright.

"Again!" the voice barked, entirely unsympathetic to his strain.

John had never been a slouch, despite the amount of time he'd spent on computers, but this was entirely beyond anything he'd ever done before. Beyond his limits, in fact, but they didn't care about that.

No, that was a lie. They delighted in seeing him go past his limits, past the point where his body said no and tried to give up. Sometimes, he thought it was their way of getting back at him for being Jeff Tracy's son. Maybe they thought they had a point to prove, a point to drive home.

Maybe they were trying to force him to admit he couldn't do it. That he really was just the pampered son of a billionaire. That he should just go home and leave the real world to the people that worked for it, rather than had it handed to them on a silver platter.

As if John's platter was silver.

Red, maybe. Black. White. Death and decay and blood and ice. Precious metals were reserved for fine instruments, like the telescope he'd saved up for, bit by bit, for an entire decade, refusing any help from his father or his brothers. Not even Mom, although in a crushing irony he'd got money from her anyway.

He hadn't touched it, just like he hadn't touched anything Dad had given him since he'd been old enough to find his own way in the world.

Despite the jeers, the cold gazes, the hissed words behind his back but clearly pitched for him to hear regardless, John was here on his own merit. And he was going to prove it.

"Again!" the commander snapped. John heaved another breath into his protesting lungs and moved, following the routine that had been drilled into him over and over and over again. He'd volunteered for this, gaining some raised eyebrows and some additional jeers. A new, experimental training programme, designed to get astronauts into shape for the dangers of deep space faster, more efficiently.

It wasn't safe. Scott would have an aneurysm if he knew what John had signed up for. It was dangerous; half the volunteers had already dropped out, either unable to handle it or crippled by a manoeuvre gone wrong. It could so, so easily end John's career before it had even begun and do exactly what all those jeering mouths wanted – send him home to live in perceived luxury for the rest of his days.

He was starting to wonder if that was what they were trying to do to him. John knew he was having less rests, less breaks, than the rest of the cohort. They were all staggered, trying to find the optimal pace, but he doubted it was coincidence that he was on the most punishing regime of all.

"Again!"

He slipped as he pulled himself back up off the floor, arms graduated from trembling to spasming, but he couldn't let that stop him, had to keep going anyway.

"Tracy, do you need to drop out?"

No sympathy in the words. NASA wasn't military, but they weren't exactly civilian either. Space wasn't forgiving enough for that.

"No, sir," he grunted, voice straining almost as much as his muscles, as he forced his beyond-exhausted body back up again.

He was going to see this trial through, come hell or high water, and he was going to prove that John Tracy was on the programme because he'd worked to be there, and not because someone had thrown money into the right person's pockets.

There was no other option.

That's certainly a very interesting combination, for sure! I wasn't entirely sure how I was going to handle this, mostly because I don't like making permanent changes to the boys and 'lab rat' very much implies some form of experimentation going on, but my muses have come up with something that's maybe a bit of a twist on the prompt, but I'm very happy with the interpretation. It's a facet of John's backstory that I've not really poked around with before…

This is the last pre-written fic that's going into this collection - all the ones I have yet to archive are 1k+ and therefore will be posted as individual works. I do still have many prompts in my inbox, though, so this won't be the last of this fic... I'll start working through that inbox again probably December-time, after fluffember is over.

Thanks for reading!
Tsari