Timekeeper by Tara Sim
"Two o’clock was missing.
In an alternate Victorian world controlled by clock towers, a damaged clock can fracture time—and a destroyed one can stop it completely.
It’s a truth that seventeen-year-old clock mechanic Danny Hart knows all too well; his father has been trapped in a Stopped town east of London for three years. Though Danny is a prodigy who can repair not only clockwork, but the very fabric of time, his fixation with staging a rescue is quickly becoming a concern to his superiors.
And so they assign him to Enfield, a town where the tower seems to be forever plagued with problems. Danny’s new apprentice both annoys and intrigues him, and though the boy is eager to work, he maintains a secretive distance. Danny soon discovers why: he is the tower’s clock spirit, a mythical being that oversees Enfield’s time. Though the boys are drawn together by their loneliness, Danny knows falling in love with a clock spirit is forbidden, and means risking everything he’s fought to achieve.
But when a series of bombings at nearby towers threaten to Stop more cities, Danny must race to prevent Enfield from becoming the next target or he’ll not only lose his father, but the boy he loves, forever."
You can read this interview with the author, where she talks about developing the magical systems of Timekeeper's world, and how few fantasy books have gay heroes. Add your review of "Timekeeper" - the first of a planned triology - in comments!