Carve the Mark by Veronica Roth

Cyra is the sister of the brutal tyrant who rules the Shotet people. Cyra’s currentgift gives her pain and power—something her brother exploits, using her to torture his enemies. But Cyra is much more than just a blade in her brother’s hand: she is resilient, quick on her feet, and smarter than he knows. Akos is the son of a farmer and an oracle from the frozen nation-planet of Thuvhe. Protected by his unusual currentgift, Akos is generous in spirit, and his loyalty to his family is limitless. Once Akos and his brother are captured by enemy Shotet soldiers, Akos is desperate to get his brother out alive—no matter what the cost. Then Akos is thrust into Cyra's world, and the enmity between their countries and families seems insurmountable. Will they help each other to survive, or will they destroy one another?