The Emperor's Mirror (Dragon & Emperor 1) MM

The monks have good reason to be secretive, given the centuries of religious
persecution after the fall of the Emperor who represented their gods.  That's to say nothing of the cult leader enchanting disciples in the next town over, or of the boy they keep hidden underground while they prepare him to be the new Emperor. Tallis, an orphan himself, feels an instant connection with Brannon, the young boy who can channel the power of the gods but is deeply resentful of the monks who have imprisoned him to keep him safe. Tallis soon finds himself struggling to unravel
not only a theft, but the murder of the last Emperor, which fractured the world a thousand years before.