I read it a long time ago. So, I remember only a few things. I think it was a soulmate fic with a Harry/Hermione ("Harmony") pairing.
Harry and Hermione go back in time to their second year, when Harry was in the chamber with Ginny. Harry tells Ginny that he failed to protect as a brother. Ginny doesn't like this. Later in the Weasley's house he apologizes again and other Weasleys hear the conversation.
After that Ginny keeps saying that she looks like Harry's mom and Harry looks like James so they should be together. All Weasleys gets disgusted listening to this (except Molly) and someone ends up slapping her.