@YenaMuffin  
I’m hoping I can explain this without coming off needlessly complicated, I like to develope world building and background lore relatively interesting and simple to understand. That’s what science fiction is to me, it’s the crutch to hold up the more wonderous or fantastical plot holes of the universe you create. I’m sure you’re familiar with fallout equestria and the post-apocalyptic world it entails. After the megaspells fell across equestria, supposedly cloudsdale was destroyed in the magical fire, but I don’t think the story ever directly goes there or confirms that. So in my head canon there are still ruins post war. Damaged, but still there. One of the few things that survived was the rainbow factory. In the show, the rainbow juice is presented as nontoxic yet volatile, meaning you can eat it, but you shouldn’t. I’m thinking the survivors of the cloudsdale ruins start eating rainbow out of sheer desperation. Think about it, volatile rainbow, a dash of radiation, and a heap of science fiction later you get thte recipe for making some unique mutants over the course of a couple generations. The mutants I’m wanting localized in cloudsdale are essentially these exploding acidic blooded jellyfish that float through the air, have rainbow colored blood under a thin translucent layer of skin, and are about three to five feet in diameter. Relatively small, and slow, but in great numbers, can ruin your day. These little things are called “rainbows”. Why are they so numerous? Why are they so rooted in cloudsdale? Well there’s a creature producing these things. One that’s found a way to do it quickly and efficiently by surviving off of nothing but a diet of rainbow. (It’s not all it eats but I digress )The big bad mother rainbow. It sprouts these things from its back. It’s the size of skyscrapers, and it wanders through fallout equestria’s thick cloud layer and emerges when ready to take prey. It’s bad news because it brings the little rainbow creatures everywhere with it. I have other creatures I’ve made too, mostly lore friendly and for the purposes of deep world building. If you’re interested maybe I could upload some more of my designs.

What is her story?