Kira felt a wave of despair, thinking that Arwen’s tiny, precious life wouldn’t even matter if she couldn’t find a way to cure everyone completely.

She dove back into her studies, determined to do just that.

RM was a shockingly complex virus that passed through multiple stages over the course of its life cycle. When she’d been studying Samm—well over a year ago, she thought grimly—she’d named these stages the Spore, the Blob, and the Predator. The Spore was the most basic version of the virus, created inside of the Partial respiratory system, where it passed into the air and, eventually, into a human body. As soon as it entered the bloodstream, usually by being absorbed through the lungs, it transformed itself into the Predator—a vicious killer that sought only to reproduce itself and build more of the Spore, attacking the host and practically eating it alive, breaking down every cell and tissue it could find in a mad rush to spread the disease to as many new hosts as possible. Carried to its extreme conclusion, this process could reduce a human body to goo, but obviously the infected person would die long before, as her organs and internal systems broke down. Most hosts actually died from fever, as their bodies fought back so violently they ended up frying themselves from within.

As deadly as the Predator was, human doctors knew very little about it, simply because it killed too efficiently. Anyone who lived long enough to be properly studied was either inherently immune—a staggeringly small percentage of the population—or infected with the third stage of the virus, which Kira had named the Blob. She had thought the Blob was the killer, but the Blob was in fact a combination of two different particles: just as the Spore reacted with human blood to become the Predator, so the Predator reacted with the Lurker, the mysterious Pheromone 47, to become the Blob—a fat, harmless, almost completely inert version of the virus. The Partials breathed out the disease, but they also breathed out the cure, which they could pass along in proximity to a human. Vale and Morgan insisted that the Trust had never intended for RM to destroy the human race, and it was the Predator they were probably referring to—RM was simply too good at its job, far better than anyone had ever expected, and the disease spread too quickly among people far from any Partials. Graeme Chamberlain had designed it, and killed himself soon after, so whether he’d done it on purpose was anyone’s guess. But the key interaction, the most important part of the process, was that third stage. The Blob. It said so much about the Trust, and about their plan, and about the man who’d come up with it.

Armin Dhurvasula. Kira’s father.