This takes place when Raditz was still on the run with Kakarrot – flashback fic! ^U^
Raditz had learned caution over the six years he'd been on the run, but there were still few things he truly feared. Death was one of them, Frieza was another. But the one to came to mind at this instant was his own body and the first step towards adulthood, his first growth spurt.
He had seen other saiyan brats go through their first spurts, seen the hunger, aggression, and pain that accompanied them. Pain he was fairly used to by this point – it was a thing all saiyans became acquainted with at a young age – but the other two? The children he had seen go through their spurts had been wild, even those with mild tempers beforehand often lost coherence by the end of it, such were their rage and hunger. And, unlike them, Raditz had no elders to guide him through this time, to direct his destructive instincts away from improper structures or items and into the desert, to add new craters to the landscape, like those before them had. He didn't even have a planet he could hide on. What he had were a ship and a baby brother to take care of.
He gulped as he looked in the mirror. He'd been hoping he'd be a late grower, that he'd have more time to get space between them and their hunters, but… He could feel the ache growing in his bones already. Barely fourteen, and already he'd grown an inch in the last week.
…Frieza wouldn't be the one to kill the last of the saiyans after all. He wouldn't have the chance, because Raditz would do it for him – one misaimed ki blast or poorly-placed punch during his growth-induced rage, and he'd destroy the ship. This was it. The end of the saiyan race.
He growled.
That didn't mean he had to meet it with open arms. Spinning on his heel, he set off towards the helm. The next months were going to be tough, and they'd need supplies if they wanted a prayer of surviving them.
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As it turned out, his first spurt wasn't as bad as Raditz had feared it would be.
It was much, much worse.
He'd been worried about ensuring he and Kakarrot had enough to eat, and had started laying in supplies the instant he realised his spurt was starting, but his real fear had been the heightened aggression and need to fight. As it turned out, food was the bigger issue.
Saiyans were generally born with the hairstyle they would wear all their lives, the exception being that some were born with bangs that stiffened and rose to join the rest of their hair during their first or second spurt, and their hair grew as they did so that it always remained proportionate. Usually this meant a few inches of growth – most saiyans had hair a bit past their shoulders (or the upward equivalent) at the most.
Raditz's hair was past his knees. He'd never thought about this much beyond basic concerns, like grooming. Now, though, the combined stress of body and hair pushing for more and more height and length left him too tired for anything more than a low-grade frustration and grumpiness. By the end of the first month he'd grown four inches and felt like he was in a state of constant starvation. By the end of the second, he'd grown six more and had difficulty training due to a continuous low-grade exhaustion and the gnawing ache in his bones, different and far more grueling than injuries he'd had in the past simply because it never went away or lessened. He had realized his mistake in preparations by that point and began laying in more food supplies – dried meats, fruits, and other foods that stored well and had a high caloric content.
By the third month, things got dangerous. He was getting more and more tired, and Frieza's men were getting closer again. Training had become a luxury he couldn't afford – it required too much energy, and it was getting harder and harder to ignore the pain. He began to lay in new supplies, components for the regen tank, clothes for when he finished growing, and data discs. If he couldn't use this time to train, he'd learn instead, and maybe find out something useful, something that would help him…
In the fourth month, he was catching himself nodding off at random intervals, and was having a hard time focusing on anything other than his pain, hunger, and exhaustion. He discovered that he could use the temporary life support systems in the helm to keep himself awake, and abused this knowledge as far as he dared. And he began to think that, while Kakarrot and the ship might survive this, he might not. And that was when the worst battle began. He made as many raids as he could, laying in even more food, fuel, medical supplies, using Kakarrot as a psychic scout to help him (it wasn't enough (it could never be enough) but he wasn't physically capable of doing more). He wasn't satisfied with what he accomplished, but supplies were really his secondary priority – his primary goal was to get a bigger lead on Frieza's forces, one big enough to find somewhere for Kakarrot to hide until he was a little older. Raditz would not let the saiyan race die because its last living member had been captured, or starved to death before he could find a home – those were things that would happen over his dead body.
And, halfway through the first week of the fifth month, it looked like they might. His body couldn't take the strain anymore, even with the life support, and he lost consciousness at the helm, too worn out to even regret the fact that he probably wasn't going to wake up again.
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Raditz woke up to find himself in the regen tank on the Frag (he'd used it often enough to recognise it from the inside), the fluid slowly draining.
He was alive.
Also tall. Apparently his body had found another foot of height between his losing consciousness and waking up, and his hair was still past his knees. He activated the internal release of the tank, dried off with a cloth, and then sorted through the small heap of clothes that had been left on the floor outside the tank, looking for something that would fit him in a mild state of shock. Then, clad in some pants that looked like they were intended to be loose but kinda weren't on him, he made his way out of the Frag's medical facilities to find Kakarrot.
The boy was at the helm, hovering over the console since his arms were still too short to reach from the chair, occasionally tapping the slightly-too-large yellow scouter he wore. Probably had a disc in there to help him navigate. Raditz leaned in the doorway and watched him for a few minutes before making his presence known.
"Hey, brat. How long have I been out?"
His throat felt a little rough, and his voice had deepened, but it was apparently still recognisable, because Kakarrot jerked to a halt over the console like he'd run into a mountain, spinning in mid-air.
"Raditz? RADITZ!" The boy zipped across the room, smacking into Raditz's chest headfirst, making his brother grunt but not doing any real damage. "You woke up! And you're all big and your bangs are gone and I've been flying the Fragment and I missed you!" all this was said in the time it took Raditz to raise his arms and return Kakarrot's hug. The small boy beamed up at him as he did. "I didn't know you had a royal's point!"
Raditz laughed and walked over to put the ship on autopilot, because it would be just his luck to survive his first spurt only to crash into a star because no one was at the controls. "I hadn't really noticed my bangs were gone. They must have stiffened up in that last however long." Now that it had been brought to his attention, it was an odd sensation, to have his forehead mostly uncovered, except for the sharp v of hair descending down its center, and he brought a hand up to explore it, feeling the shorter hairs that used to hang in his face now lying stiffly among the longer ones. He'd have to take a look later. "How long was I out for?"
Kakarrot hesitated. "I… think it's been a month. But I'm not sure."
Raditz snorted. "You can pilot the Frag, but you can't tell time?"
Kakarrot scowled. "I've seen you pilot the Fragment lots – I've never seen you tell time! Anyway, you should be grateful – I kept us safe while you were sleeping!"
Raditz gave his younger brother a fond smile. You did a lot more than that, brat. He kept the thought to himself, though, merely saying. "Guess you did. How far behind are the hunters?"
"Um…" Kakarrot frowned and squirmed loose to scamper back over to the console. After staring at it for a moment, he pressed a button, which pulled up a screen. "That far."
"Hn, three days. Not bad, Kakarrot, not bad at all." Walking over, he grabbed his brother around the waist with his tail and lifted him up (and wasn't that the weirdest thing? He was used to being about a foot taller than the boy, but now he towered over him). Kakarrot giggled and wrapped his arms around the furry limb, and Raditz snickered as well. Against all odds, he was alive – again. "I think piloting like that deserves a reward and, anyway, I'm hungry; let's eat."
"FOOD!" Kakarrot cheered, waving his arms over his head.
Raditz grinned at him. "Yeah. I was thinking some pyup berries?"
To his surprise, Kakarrot shook his head adamantly, looking a little green. "No pyup berries."
"Why not?" Pyups weren't actually berries but a nutrient-rich fruit with a tantalizing aroma and flavour, and usually Raditz had to strictly ration them out to his brother.
"I found your store of them while you were asleep," Kakarrot looked decidedly ill now, "I don't think I like pyup berries anymore."
Raditz snickered as he made his way towards the kitchen area, and Kakarrot glowered at him.
"It's not funny!"
"Sure it is – I always told you you'd get sick if you ate too many of those things and that I'd laugh at you if you did." The newly-tall saiyan smirked.
"You're evil!"
"And you're a punk, so I guess we're even." Plunking Kakarrot down on the table, he went over into the cold store that made up most of the room and found a couple packets of dried meat. Walking out again, he tossed one at his brother, who tore into it happily. "Things are looking a little low in there; how's it compare to the hold?"
"Haven't been to the hold much for food since the pyups," Kakarrot paused to swallow, then continued his report. "We're definitely low on supplies for the tank, though."
"Speaking of which, what made you think to put me in there?" Raditz asked curiously, tearing into his own meat. It tasted divine after a month of no food, even if it was a month he'd slept through and the tank had been supplying him with the necessary nutrients the whole time.
Kakarrot tilted his head to the side. "You wouldn't wake up, and your face was all scrunched up like something hurt, like when you've been in a fight and something gets broken." He shrugged. "You usually go in the tank after that, so I put you in there and hit the life support button, like you showed me."
And thank the gods it had occurred to Raditz to teach Kakarrot the basic tank settings when he was thirteen and the brat was a bit past five – it had apparently saved his life. The boy was looking at him curiously now.
"Did I do the right thing?"
"Yeah, exactly the right thi-" at that moment, the ship lurched, throwing them both off-balance and putting praise on the back burner for the moment. "WHAT THE HELL WAS THAT?!"
Kakarrot shrugged, unconcerned. "Dunno. It's been doing that every now and then for a couple weeks."
"What do you mean you don't know?!" Raditz was already running through several scenarios in his head that could have caused the Frag to be doing this, and none of them were good.
"I'm not allowed in the engine room without you, on pain of pain," Kakarrot replied primly, "And if you're going to go deal with an emergency, can I have your meat?"
Cursing, Raditz threw the packet at the boy's head and then dashed to his room to grab his tools before heading to the engine room, managing to only bang his head twice on the way there. He then spent an exciting two hours convincing the engine that it really did want to keep being an engine, as opposed to its new ambition of becoming a lump of molten slag.
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In the following weeks, Raditz caught up on his training, repaired the engine a few more times, adapted to his new height, and got some clothes that fit relatively well, the process of which left one alien telling his buddies how he'd been minding his own business when a half-naked saiyan appeared out of nowhere and stole his armor.
Over the following years, Raditz formally taught Kakarrot how to fly the Frag and found him some discs on piloting and navigation when the boy expressed an interest. He also began increasing Kakarrot's training, because his little brother's power level was growing quickly, far more so than his birth power had indicated possible, and Raditz had no doubt at this point that Kakarrot would surpass him before the boy hit his second spurt. Mostly, though, he was just relieved to have someone else to pilot the ship, and to have some back-up in tight corners.
Raditz began preparing for his second spurt six months before he turned nineteen. The second wasn't as bad as the first, supposedly, but, after nearly dying, he was taking no chances. And it turned out he needn't have worried. After growing almost three feet in five months, growing one in two was nothing. He upped his training regime, spent a night or two a week in the regen tank, ate a ridiculous amount at meals – even for a saiyan – and for the most part was okay, other than a certain amount of tired and achy-ness, a minor spike in aggression, and some sensitivity at the base of his tail. Raditz sauntered out of that period fully grown – seven feet tall, with hair still past his knees and a power level of 1500, which wasn't too shabby for a third class who gained power slower than a Clorphor handing over money.
He also handed full control of the helm over to Kakarrot at that point, switching his own attention to researching star charts. They had a minimum of three years before Kakarrot hit his own first spurt, and Raditz was an adult now. It was time to quit screwing around, shake Frieza's goons for good, and find somewhere they could stand still awhile and catch their breaths. He would find a place, Kakarrot would chart a path, and together they would make sure they got there in one piece.
As it turned out, things didn't go quite as Raditz planned.
They went much, much better.
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It is shit like this that make the Raditzs living in my head question whether I really like them best, or whether I'm just messing with them. (And yes, Raditzs, plural – every fic I write with this guy in it spawns a new variation of him. It's interesting seeing how they compare and contrast in various ways.)
Hair is made of protein fibers, so you need protein to grow more of it, same as muscle mass. And with saiyan hair as thick and sturdy as it is (at least in this universe), this would make simultaneous accelerated hair and body growth extremely taxing on Raditz, moreso than a saiyan with shorter hair, as both systems would be drawing on the same resource in huge quantities. (I am fairly sure this is pretty legit, I did some research on hair. Any inconsistencies with actual science, I accredit to the face that Raditz is of an Alien Race.)
In regards to saiyan puberty, obviously not everyone has it as rough as Raditz did, his luck was just bad (as per usual at this point in his life), nor is it necessarily even as rough as it is described in this fic. Some saiyans have an easier transition to adulthood than others, same as humans, but it's the rougher transitions that stuck in Raditz's mind and which saiyan children were prepped to handle (sort of worst case scenario training). As to why I didn't say this in the fic, it's because it was written in third person limited perspective, and that perspective was Raditz's, so since he didn't really remember the potential for smoother spurts, neither did we.
On how Kakarrot can fly a spaceship at age six: I'm not trying to make Kakarrot a genius in this, or even abnormally intelligent. The way I see it is this: saiyans are born with their brains more developed than human children, so they start learning and remembering things a lot faster, and mentally mature more quickly in some ways, based heavily on how Gohan acts at age four and also on the fact that Broly apparently has coherent memories from when he was nearly a newborn. Kakarrot has spent a lot of time in the helm of the Frag pretty much since the beginning, because Raditz kept him up there while he was flying it so he could keep an eye on both the ship and his brother at once. Kakarrot's young, but his mind's active, so, between chasing his tail, chasing Raditz's tail, and demanding food, he watched his brother fly the ship and got a basic feel for it, like a kid watching their parent drive the car and learning the basics through observation (I imagine non-Earth spaceships like this one are pretty simple to fly, since they are like the cars of the universe). And I do picture Kakarrot as being smarter than Goku, for one simple factor: Kakarrot does not have brain damage. Goku does, it's canon (and it is for this that I forgive him many things, just as I would a normal human with brain damage).
Raditz, start of first spurt: 3'2"
End of first spurt: 6'0" and gangly, like a human teenager
End of second spurt: 7'0" and looks proportionately the way he does when introduced in the manga, possibly slightly less muscle mass