Six letters ended the world.

We didn’t realize it at the time, swept away in our excitement of advancing technology and endless possibilities. We failed to predict all that would follow. Perhaps they wouldn’t have made the same mistakes. Perhaps they would have been more cautious. Perhaps not. History cares not for your regrets, pays no heed to your guilt. History’s purpose is not the past but the future.

It started with CRISPR: Clustered Regularly Interspaced Short Palindromic Repeats. Segments of prokaryotic DNA from bacteria hiding a remarkable secret. In the early twenty-first century scientists first used CRISPR to edit human genes, fixing nature’s flaws. Early applications focused on combating illness—preventing cancer and immune disorders before they developed—but that was just the beginning. In hindsight, what happened was inevitable; sooner or later, humans were bound to be tempted.

Humanity had to make themselves better.

At first, we didn’t grasp the significance of what they were doing—or how far they had progressed. We were too accustomed to our own superiority. But as humans lived longer, grew taller, became stronger, doubt set in. Every year, they became more like us, until fear finally forced our hand.

We lobbied governments, seeded grassroots scare campaigns, and made exorbitant political donations. Several nations passed our legislation prohibiting the technology, but it was too late; the wealthy had a taste of the future and were hungry for more. They bankrolled institutes in countries we couldn’t control, drove the science ever further with dreams of perfect superhuman heirs. As the black market exploded, military powers embraced the opportunity to design superior soldiers, and human evolution accelerated.

We couldn’t prevent the advance, so we turned the technology on ourselves. A genetic arms race began, albeit one to which humanity remained oblivious.

Initially, our experiments were promising. The virus responsible for our existence already altered us, transforming us over decades into a new species: Homo meliora. With CRISPR, we intended to refine, streamline, and embellish that process. Meliors would transform faster, evolve further, remain ever one step ahead.

Such hubris.

Human media called them blights. Soon we did too. The strain they carried was incredibly virulent, a single bite sufficient to infect a new host. If the victim survived, it took as little as twelve hours for the host to succumb. Driven mad with the urge to feed, they became violently unstable, attacking any living creature they could find. Most frequently, that meant people.

Entire communities were decimated, their populations dead or assimilated into the growing horde.

Human denial prevailed longer than we thought possible. Videos streamed on social media and news networks were declared a hoax, preventing an effective response. Minsk was the first city overrun; an entire population dead or turned within a fortnight. World leaders finally conceded the blights...