Astoria of Slytherin: The Complete Series

Astoria Greengrass and Draco Malfoy clash when they meet. (It's not Draco's fault Astoria's best friends with the only Muggle-born in Slytherin, right?) Their habit of keeping things from each other dies hard once the war creeps upon them. It takes some time and several mistakes, but they come to understand what it means to really love another person through thick and thin.