"Arbitrium" is a post-apocalyptic Tor.com Original short story from Anjali Sachdeva, author of All the Names They Used for God. Vashti is a pathogenic diplomat—an ambassador to the world of viruses, whom she communicates with through a machine that can translate their chemical signals into images, tastes, smells, sounds, and memories. She begins a negotiation between the US Government and a diplomatic contingent from Arenavirus, a virus which has just begun spreading a deadly mutation in Florida. If Vashti is successful, she and Arena will reach a diplomatic agreement; if not, the Arenavirus infection will continue to spread, and humans will have to race to try to find a vaccine or treatment. As she navigates the diplomatic discussions, Vashti is also trying to connect with her daughter Alma, who lives on the other side of the country in a technology-averse commune. By the time the negotiation ends, Vashti discovers that Arenavirus have learned some impressive and deadly tricks from their interactions with humans. At the Publisher's request, this title is being sold without Digital Rights Management Software (DRM) applied.