Blood Rights

When the job goes wrong, it doesn't go wrong the way Owlantoo expects. He's a professional. He's been doing this for a long time, across more star systems than most species know exist, and he has never once left a contract unfinished. The target on Bardland - a dim, tidally locked world orbiting the dying ember of Barnard's Star - is no different from a hundred others. Get in. Get it done. Get out.
Except the target gets one last piece of him on the way out. A bite. Small enough to almost miss. Carrying inside it sixty thousand years of evolved biological weaponry. The Skriath don't need soldiers. They never did. Now Owlantoo has days to live unless he can get the one thing the virus has made his body dependent on - humanoid blood, delivered directly into his system, in quantities that no single source is going to hand over willingly.
The cure exists, back on his home planet of Tanrigel. The problem is the math. Twenty-six days to get there. Seven days before his body starts shutting down. One planet close enough to matter. Earth. A pre-contact world that has no idea the universe is watching. A species that has somehow managed to develop refrigerated blood storage, nuclear weapons, and a mythology about creatures of the night that drink blood, all at roughly the same time.
A planet that is, in every way that counts, completely unprepared for what is about to land in one of its cities. Owlantoo has his ship, his technology, his training, and Zorae - the AI who has been with him for a hundred and forty years and has strong opinions about how this ends. The clock is running.