A new generation of wizards and witches could be the main characters. For example, the children of Harry and his friends. They could inherit the legacies of their parents and at the same time, carve out their own identities as they struggle to survive and rebuild in a world that has been turned upside down.
Maybe Neville could be a central figure. He has always been strong and determined. In a post - apocalyptic world, his skills in Herbology could be extremely valuable. He could be in charge of finding or creating new plants that can provide food, medicine, or protection against the new threats in the world.
One great post apocalyptic Harry Potter fanfiction is 'The Shattered World'. It presents a dark and desolate world after a magical cataclysm. The characters have to fight for survival in a way that's very different from the original series. Another one is 'Surviving the Ruins' which focuses on how the Hogwarts students band together against new and terrifying threats.
In post apocalyptic Harry Potter fanfiction, a common theme is the breakdown of the old order. Hogwarts might no longer be the safe haven it once was, and the Ministry of Magic could be in ruins. This forces the characters to create new systems and ways of living. Another theme is the discovery of new powers or abilities. With the world in chaos, some characters may find hidden strengths within themselves that they never knew existed before, which helps them in their fight for survival.
One interesting concept could be the rebuilding of Hogwarts. After an apocalyptic event, the once - great school might be in ruins. The remaining wizards and witches could come together to restore it, using their magic in creative ways. They might have to find new sources of magical energy or deal with dark magic that has been unleashed during the apocalypse.
One idea could be that a dark magic spell has backfired and decimated the wizarding world. Harry and his friends, now much older, have to find a way to restore magic to its former glory. They might search for ancient artifacts that can reverse the damage.
Luna Lovegood could be a main focus. Her unique perspective on magic could be used to discover new magical phenomena that emerged after the battle. She might also be helping the other students deal with their post - battle stress, using her calm and dreamy nature to soothe them.
I'm not sure specifically as I haven't read this novel. But typically in a post - apocalyptic novel, there would be a strong - willed protagonist, perhaps a survivor who has some special skills like hunting or fixing things. There might also be a sidekick character, someone who provides support or a different perspective to the protagonist. And there could be an antagonist, like a group leader who is power - hungry and causes trouble for the good guys.
Perhaps a group of radical wizards who believe that the apocalypse was a sign that the old ways of the wizarding world were wrong. They want to create a new order, even if it means using cruel and unethical magic. They see the more traditional wizards, like those who were friends with Harry Potter, as enemies who are holding back progress.
Albus Severus Potter is quite popular. As Harry's son, he has a lot of potential for new stories. He's in a unique position, being named after two great wizards, and fans like to explore his journey at Hogwarts and how he deals with the legacy of his father.
Luna Lovegood is an interesting choice. She has such a unique perspective on the world, and in the post - war era, she could be involved in exploring the more hidden and strange aspects of the wizarding world that were overlooked during the war. Maybe she discovers new magical creatures or lost spells.