House of Sky and Breath by Sarah J. Maas

Bryce Quinlan and Hunt Athalar have made a pact. As they process the events of the Spring they will keep things – platonic – until the Solstice. But can they resist when the crackling tension between them is enough to set the whole of Crescent City aflame? And they are not out of danger yet. Dragged into a rebel movement they want no part of, Bryce, Hunt and their friends find themselves pitted against the terrifying Asteri – whose notice they must avoid at all costs. But as they learn more about the rebel cause, they face a choice: stay silent while others are oppressed, or fight. And they’ve never been very good at staying silent.