Something survived.
A single microorganism. The one thing to have the slightest immunity to the extinction detonators used in the war.
It photosynthesised.
It, slowly but surely, crawled back from the gates of death. And the first thing it did was divide. Splitting over and over, producing more and more of itself and until the gelatinous mass managed to barely scrape itself into some sort of cooperation.
Forming two proto-eyes.
Eight pseudopods, allowing it to crawl around its new environment.
And lastly, an orifice with a single sensory organ.
The creature looked at itself, getting its first glimpse at the world.
And the first thing it saw was the toxic waste canister suspended in its centre. It smiled cutely. The creature was, against all odds in its ravaged environment, absolutely adorable.
And INCREDIBLY radioactive.