Ron and Ginny Weasley
As far back as Ron could remember, he'd thought of Ginny as his . She had belonged to him in the same way that Charlie belonged to Bill, or Fred and George belonged to each other. Of course, all of Ginny's big brothers were protective of their baby sister, but Ron had been the one to be there for her while the others went off to school and later more exotic climes. He had been her protector and her playmate from the day she was born. To Ron, Ginny had been just another brother until he learned...
Incest