Perhaps the fanfiction has a twist where the identity of the 'Boy Who Lived' is questioned or manipulated, and Harry and Ginny have to navigate through the confusion and chaos it creates in their lives.
It could be a story where someone else is mistakenly believed to be the 'Boy Who Lived' instead of Harry, and Harry and Ginny's relationship plays out against that backdrop.
Maybe it's a tale where a character other than Harry takes on the role of the 'Boy Who Lived', and this causes complications for Harry and Ginny's romance. There could be misunderstandings and challenges as a result.