Catherine Doyle and Katherine Webber are both bestselling and award-winning writers of YA and children's books. In addition to cowriting the Twin Crowns series, they are sisters-in-law.

Catherine grew up in Galway in the west of Ireland by the sea. She is the author of the Blood for Blood YA trilogy and the middle grade Storm Keeper trilogy. She currently lives in Ireland with her husband, Jack, and their dog, Cali.