The Heartless Emperor by KyokoTakanashi at Inkitt

Summary

They called him the Heartless Emperor. At sixteen, Nolan Aurelius murdered his family and seized the throne. For twelve years, he ruled through fear - a monster incapable of mercy. The world trembled at his name. Until he saw her. Clara - the Sunshine of the Village, an angel who believed even the darkest souls could be redeemed. She should have run from him. Instead, she asked him why.