Okay, so Raditz/Launch is definitely one of those 'blink and you'll miss it' pairings that somehow sprouted in the wilder corners of the fandom. I stumbled across a few fics years ago, mostly on FFN. The core dynamic always seemed to circle around two people who were, in their respective universes, kinda discarded or reduced to a single joke. Raditz is the disappointment, the weak Saiyan, the guy who shows up to be a threat and then is immediately overshadowed. Launch is the split-personality maid/bank robber who the series just... forgets about.
A lot of the fics I read played with that shared theme of being afterthoughts. One story had them meeting in some neutral city, both trying to live under aliases, both terrified of being recognized for who they used to be—Raditz the alien invader, Launch the wanted criminal. It wasn't about power levels or galactic conquest; it was two people brewing terrible coffee in a tiny apartment, jumping at shadows, and finding a weird, quiet solidarity in being nobodies. The tension came from whether Launch's sneeze would trigger her other self and scare Raditz off, or if Raditz's lingering pride would make him bolt. It was less romance and more a study in shared paranoia.
I remember one author framed Launch's dual nature as something Raditz could actually understand better than any human—Saiyans have their Great Ape transformations, after all, a total loss of control triggered by a celestial body, not a nose tickle, but still. He wasn't freaked out by her; he was cautiously fascinated. That angle made more sense to me than forcing some epic love story. They're both broken toys from the author's box, and the fanfiction is just shaking them together to see what rattles.