A Crystal in the Shadows (Boom! Shadow x OC! Reader)

(Edit: 8/4/23) This book will be renamed from Chaotic Love to A Crystal in the Shadows. Don't wanna confuse anyone. A villain and a hero? Quite a cliche couple, you might say. But this duo's relationship is put to the test when the other has a whole kingdom to save from a deadly beast. Will they fight through? Or fall apart?
(Edit 8/4/23: Shadow is so out of character in this book)