If it is AU, in the modern day, would you just want to push the second war up to our current time? What characters were you thinking of using? It could be possible that if the war went south (well technically it did) for the baddies, they could just go into hiding in the modern muggle world and try to figure out how to reclaim their position of power. But again, I'm blanking on a real conflict that can kick start some decent development, it depends if you enjoy slice of life pacing or prefer something else.