Starless. Fated Stars, #2

Evil spreads its wings. Hope withers beneath its shadow. Darien, hunted by the very magicians who trained him and marked for death after breaking his oath, has only one goal: survive long enough to reunite with his beloved Kiri. Yet it is not his pursuers he fears most. A dark power is awakening within him, one he does not understand and cannot control. With every passing moment, it presses closer to the surface, threatening to consume him.
For Kiri, life has become a cage. Bound to her homeland by the magic of her kind, she can only wait and hope while the boy who risked everything for her faces unknown dangers alone. She refuses to believe their story ends this way and searches for a way to cross the boundaries that hold her captive. In a hidden sanctuary, Arrin learns to wield her gift of prophecy. But her visions reveal a world shadowed by ruin, and Darien stands at its center, leaving her torn between the possibility of saving the future and the reality of betraying her friend.
Meanwhile, whispers of an ancient evil stir, and two young royals-one on the land, and one under the sea-must decide what they are willing to risk. and what they are willing to destroy.