"Is it?" Keres pulled down a bandolier of plasma charges and slung it over Helena's shoulder. "Then where are the others?"
When he asked for the others, he meant the lower-tier soldier zergs, the ones this batch of substance was supposed to awaken.
Each injection was meant to open a little door inside a human body, a tidy hatching chamber for the shrunken version of a half-conscious soldier zerg.
Their master managed to seed them into human bodies, finding a loophole in the secondary gland to prevent being caught.
Years, months, Keres couldn't even begin to remember when they were injected in their bodies.
They only knew that they were the chosen ones by their master to fight and end this war.
Once injected with the substance, they could begin slowly taking over the human body, just like an inconspicuous virus spreading into the computer, slowly but surely.
At the end, Zergs could completely take over the human body without damaging their real body.
