Things to know, as this is an extremely AU take - and full disclosure, I've never watched a single episode of Dragon Ball. I just play Dragon Ball Legends and I kinda fell in love with the concept of Saiyans, if not necessarily their execution.
-Caulifla's the youngest kid of Gine and Bardock, was born in Xandar, and hasn't stepped foot in her species' homeworld
-Incidentally, planet Vegeta was never destroyed by Frieza. Things are still kinda shitty for Saiyans, but y'know. No genocide.
-Kale is an orphan, and the younger sister of Broly.
-Bardock is a grumpy old man, confined to a hoverchair, constantly complaining about the soft life they lead in Xandar
-Gine owns a bustling little deli shop in Xandar's capital
-Kakarot trains non-stop to one day beat his nemesis in sports - the undefeated champion of the Tournament of Power, Broly
-Raditz is a bounty hunter, operating out of Knowhere

Lots more changes, but that's your primer! Any questions, let me know!

Caulifla has never really been much for learning Saiyan history.

To be fair, there's really not much of it; her species comes from a planet whose very name is ephemeral, changing to match that of its current ruler – King Vegeta, planet Vegeta – and the Saiyajin of old were, by all accounts, more interested in beating the shit out of each other and everyone around them than in registering the events their violent civilization went through. On top of that, and unlike her parents and brothers, she's never stepped foot on the Saiyan homeworld – as far as she's concerned, she's a citizen of the Nova Empire.

Now, though, as she stares in disbelief at the extra pair of arms of this strange, new form of hers and Kale's, she kinda wishes she'd paid a bit more attention to her father's lectures.

It all starts because of the wreckage they find, nearly a month after Ronan's failed attempt to destroy Xandar. It's a Ravager M-Class Hunter-Killer, crash landed in the outskirts of the city, and thus deemed a low priority salvage and clean-up operation by the Nova Corps. Pieces of the broken ship landed near a long-abandoned factory she and Kale usually hang out at, so they've been following the trail to the main fuselage, which they find half buried into an otherwise idyllic little grassy knoll, and strangely surrounded by a friggin' platoon of dead Sakaaran soldier drones.

Kale nearly books it back to the city on the spot. Caulifla's more focused on what a badass the Ravager pilot must've been.

Soft spot that she has for Kale and all, Caulifla takes all the corpses and tosses them into a nearby lake, and the pair gets to spelunking. The inside is...filthy, as befits a Ravager starship – again, Kale is not a fan – but Caulifla's too enthralled to care. There's bottles of liquor strewn all around, trophies taken from defeated foes – everything from reptilian skulls to a dented Nova soldier's helm – and a broken, yellow-plated android that Caulifla is ninety-five percent sure is one of those infamous Contraxian Love Bots.

That one she ushers Kale away from.

Eventually, she forces the lock of the armory compartment, digging into its mostly intact contents. "Oh, nice!" –Caulifla says, excitedly picking up a pair of Quad Blasters and holding them in what she deems a cool pose. "How do I look?"

Kale giggles. "Like a kid raiding a space pirate's armory, silly."

Caulifla rolls her eyes. "Oh, the guy's not coming back for this shit." –she shrugs. "Far as I'm concerned, this is mine now."

"What would you even do with it, Cauli?" –Kale shakes her head.

"I dunno. Maybe we could start our own Ravager clan." –she suggests. "Sail the starry seas, beat self-righteous pricks up...rob Uncle Turles blind." –she snickers. "Sky's the limit. And not even then, if we can fix this bucket of bolts up, somehow."

Kale tilts her head. "I'm pretty sure your uncle has us beat in the piracy department."

Caulifla primes the blaster, pointing at the ceiling. "Oh, I've picked up a thing or two over the years. Mama doesn't like it, but he's given me a few pointers." –she says. She demonstrates by firing a couple bolts, which go through the slowly rusting metal like it's not even there.

"I thought you wanted to be a bounty hunter, though? Like Raditz?" –Kale says, after a moment of staring at the unnecessary new holes in the hull, raising an eyebrow.

The wild-haired teen blows air out, like she's deflating, falling onto her back. Hitting the frigid metal floor barely fazes the Saiyan. "I don't even know anymore. Raditz's job is cool and all, but...there's so many rules to it. And, like, half the time you're just waiting on a bounty, or stalking a dude because he's hiding on a backwater planet, or he bought out a Kree Warlord or whatever. The more Raditz tells me about the job, the less I wanna do it, y'know?"

Kale hums. She doesn't, not really – she'd probably be perfectly happy with whatever Nova Corps-assigned job she'll get once she turns twenty-one, or Kai forbid, as a housewife – but her fellow Saiyan has always at least tried to, unlike the rest of her family. They might phrase it differently, but they all want her to follow in their respective footsteps; Kakarot explicitly wants her to train at Old Man Gohan's dojo and eventually enter the Tournament, Bardock keeps loudly talking about how Prince Vegeta is looking for a new bodyguard, and her mother none-too-subtly expects her to be the one person in the family not to drop out of school at least until she finishes college.

Only Raditz and Kale avoid putting that kind of pressure on her – and even then, Raditz doesn't because he probably doesn't give a shit.

She sighs, then puts on a cocky smirk. "So, what about it? You in for some space adventures?"

The taller Saiyan lays down next to her. "Hmm. Being whisked away from the comfort of my fancy, state-funded orphanage to live day by day as one of the group of ruffians famously wanted throughout most of the known galaxy, not knowing if I'll live to see tomorrow?" –she pretends to consider.

Caulifla winces. "...with me?" –she reminds her, meekly.

Kale laughs. "Well, duh. I told you, I'd follow you anywhere."

"Yeah, well. We were tiny babies when you said that." –Caulifla defends herself.

"We were eleven, Cauli. Practically teenagers."

"Babies, I said!" –she chuckles, then turns to stare at the green-eyed Saiyan. She's...way too close, and Caulifla is suddenly all too aware of the fact that she was too lazy to wash her teeth after breakfast today. "So, you mean it?" –she asks, tentatively.

Kale raises an eyebrow. "Unless you plan on diving into a black hole or something, yeah."

"Well, who knows? Maybe there's some cool shit at the bottom, you don't know."

"I happen to pay attention in Astrophysics, so I definitely do know." –Kale says, sarcastic. "Nothing down there but infinite gravity and space-time stretching forever and ever, until they cease to have any meaning."

"...well, it definitely sounds like Astrophysics class." –Caulifla jokes, which Kale rewards with a snorting laugh.

The pair locks gazes, not for the first time. They've always been close – Caulifla being something of a chronic vagabond, and Kale trying her best to hide away from the scrutiny that comes with being the sister of the undefeated champion of the Tournament of Power. Recently though, their friendship's gotten...charged, with something not entirely unpleasant. It makes the normally brash Caulifla nervous, and the normally meek Kale daring, and their dynamic has yet to settle into...whatever it's becoming.

Well, Caulifla knows, but she doesn't dare name it. Not yet.

Kale's eyes narrow, and she begins to lean towards her, but something causes her to glance towards the ceiling. Caulifla follows her gaze, and finds herself gasping; the fuselage's main support beam is rapidly bending, damaged beyond repair by her careless shooting, and a large section of the hull is moments away from falling right on top of them. Caulifla curses, frantically trying to remember the ki blasting technique Kakarot taught her years ago, but she only succeeds in making her hand glow. The hull fragment breaks off, and Kale leaps on top of her, trying to shield her with her body.

What happens next is...confusing.

There's a great flash of light and heat, and a thunderous crash as the debris makes contact. But Caulifla doesn't feel herself pop, or her bones crack; instead, she seems to have swapped places with Kale, who's...nowhere to be found. She rises, the massive sheet of metal on top of her sliding off of her body like it's no heavier than her bedsheets.

She stares at the debris, bewildered. Saiyans are strong, certainly – one of the strongest races in the galaxy – but...not that strong.

As the shock passes, the feeling of disorientation grows to nearly unbearable levels; it's like jumping through one too many warp gates without moving at all – and, on top of that, everything seems to be the wrong size. Caulifla's positively tiny, for a Saiyan – even with her signature wild mane, she barely reaches Kale's nose – and now she feels cramped, in a cabin intended for a crew of five humanoids. Her clothes are tearing, too, barely holding together as she moves around, strained by her body's apparent growth.

"What the fuck?" –she wonders aloud, staring at her hands...and then shrieks, as another set of arms comes up underneath them. She follows the new limbs, and realizes they've sprouted from just underneath her regular arms. Stumbling on legs way too long to be hers, she searches for the closest reflective source available – the transparisteel viewport on the cockpit – and gasps as she sees an entirely different person staring back at her.

It's like...well, it's like she and Kale had a baby. A massive, four-armed, apparently twin-tailed baby. Their skin tones are mixed, their hairstyles have merged, and the eyes are mismatched – one black, like hers, and one green, like Kale's – and judging by the fact that one of her hands is reaching out to touch the cracked, crystal-like metal without any input on her part, she's pretty sure that's no coincidence.

"We fused." –she hears herself say. The voice, she now realizes, is twofold; hers and Kale's, the words uttered at exactly the same time, in exactly the same tone. "I-I...how?"

"I don't know." –Caulifla says, the voices hollow. "I didn't...I didn't even know Saiyans could fuse."

The fusion blinks, looking back to the spot where they merged. The heat was, apparently, so intense it melted the metal underneath them, still glowing faintly in the relative darkness of the ship's interior. "I've never heard of this before, either." –Kale says. "...what do we do? Should we unfuse?"

"No shit, we have to unfuse." –she says, hating the fear that colors their voice.

"But...how? We don't even know how we fused in the first place." –Kale reminds her. "We need to ask your parents."

Caulifla winces. "Yeah, that's not happening. Bardock's gonna go apeshit if we show up like this. You know how he is about Saiyans getting body mods. He won't even accept an implant that'd let him walk again; he'll blow a fuse at this." –she says, gesturing at their shared body. She doesn't even want to think about what Gine will say, though for entirely different reasons – her mother is, bar none, the biggest proponent of her and Kale's ongoing...thing.

"What 'thing'?" –Kale asks, making Caulifla blush inside – which quickly reflects on their fused visage. "...Caulifla, why are we blushing?"

"N-nothing, forget about it!" –Caulifla hastily stammers. "We need to find someone else. Some egghead who can zap us apart or whatever."

"Cauli, talk to me." –Kale ignores her, gently prodding. "I'm trying my hardest to push your thoughts away, but you're...thinking too loud. What don't you want me to know?"

"I...later. This isn't the time." –or the way, she thinks. "Please, can you think of anybody who might be able to help?"

Kale sighs. "I...guess we could try going to the xeno-geneticist who studied my brother's anomalies. Doctor Bulma Briefs."

Caulifla tilts their head. "The Capsule Corp heiress?"

"That's the one!" –Kale nods for them both. "How'd you know of her?"

"She married the Prince of all Saiyans." –Caulifla says, sarcastically. "We went to the wedding when I was...five, maybe? Got invited because of Bardock's sacrifice and all."

"Huh." –Kale says. "Well, she studies the Saiyan genome...maybe she knows something about fusing?"

"If not, she could probably figure it out. It's worth a shot."

As always, thank you for your attention! Make sure to comment or message me if you have any questions about this story. Look me up on Twitter as Darthkvzn or Tumblr as darthkvznblogs if you'd like - and on Ko-fi, as Darthkvzn, if you like what I do and have a coffee's worth of money to spare.

This is intended as a 3-5 chapter fic, but knowing me, I make no promises! Hope you enjoyed!