#41 This Is How You Lose the Time War by Amal El-Mohtar, Max Gladstone (

This is a great epistolary novella set with the two main characters on opposite sides of a war that spans through time and various parallel worlds. What starts as taunts back and forth from both Red and Blue it slowly evolves to friendship and respect and then something more. As each message is written to be read once and then destroyed in so many different ways a mysterious third person has been collecting both sets of notes and reading them. By the end of the story the third party is revealed, and it makes for a great read.