"The First Kill" was published in the anthology Blackguards: Tales of
Assassins, Mercenaries, and Rogues.
About this story, author Django Wexler says, "'The First Kill' is a bit
of backstory for the universe of The Shadow Campaigns. It's always hard
to give a proper spotlight to the villains in a novel where they don't
get a POV, so I wanted to take this chance to explore that a little.
The Shadow Throne implies a connection between Andreas, Duke Orlanko's
brutally efficient go-to killer, and Sothe, the Gray Rose, his best
agent turned bitter enemy. In this story, we get to see these two at an
earlier point in their careers, and take a look at how that relationship
got started."