Scythe by Neal Shusterman
In a future where humanity has conquered death and the world is governed by an advanced AI, the population must be controlled by Scythes—individuals entrusted with the power to take life. Two teenagers are chosen as apprentice Scythes and must learn the art of killing, but as they delve into their grim responsibilities, they uncover the corruption within the Scythedom. As they grapple with the morality of their roles and the political machinations of their superiors, they must decide what kind of Scythes they will become and how they will shape the future of their utopian society.