A post HBP book seven substitute started well before DH. It is a HHr book. Ron and Ginny stay likable. I try to stay with the canon as much as possible and will eventually explain all actions and abilities. Please read the intro for more details.

Harry Potter won the Second Blood War and defeated his enemies... and was left with nothing. Decades later, he contributes to the creation of a revolutionary new piece of technology and destroys the future in order to rewrite his own past...