The one where both Harry and Draco are married for convenience, and then Ginny and Astoria get together and they get into each other's lives. Harry/Draco, side Ginny/Astoria.

"The problem is exactly that," Dominique said. "Voldemort was destroyed and everybody settled down and enforced some laws so that he could never return. All good and all well, except…" "Except," Mea interrupted, a glint in her eyes, "except everybody just rested on their laurels. Even uncle Harry went to be an Auror and an enforcer of the same system that needed change"

Mr and Mrs Dursley, of number ten, School Street, were proud to say that they were perfectly normal, thank you very much. [Or, Dudley's daughter is definitely a Witch, and Dudley's cousin is there to help her. And maybe him too.][Or, how Dudley definitely changed and Harry discovers that.]