One idea could be to focus on the role of artificial intelligence in the war. Maybe AI systems start making decisions independently, leading to unforeseen and dangerous military actions. For example, an AI - controlled drone fleet goes rogue and attacks both sides' military bases, which then escalates the conflict between nations.
The novel could start with diplomatic breakdowns. Show the failed peace treaties, the misunderstandings in international conferences. For instance, misinterpreted statements by diplomats that lead to increased tensions between major powers.
One main idea is the global scale of the zombie apocalypse. It shows how different countries respond to the sudden and overwhelming threat. Another is the survival instinct of humanity. People have to adapt quickly, whether it's finding food, shelter, or a way to fight the zombies. Also, it explores the breakdown and re - formation of society. Laws and social norms change as people struggle to stay alive.
One idea could be a story where the Navy is tasked with transporting survivors during the World War Z apocalypse. They have to deal with zombie attacks on their ships and at ports.
The main ideas involve the chaos caused by the zombie outbreak on a global level. Countries are in disarray, and people are forced to fend for themselves. It's about survival against the undead.
Perhaps in the fanfiction, North Korea has developed some sort of special technology or antidote that could potentially stop the spread of the zombie virus in the World War Z scenario. This would make them a key player in the global fight against the zombie apocalypse. They might share this technology with other countries in exchange for resources or alliances.
One idea could be a story where the inklings and octolings have to put aside their differences during a world war - like situation. They could form an alliance to fight against a common enemy that threatens both of their species. Maybe this enemy is a new type of sea creature that has been mutated by some sort of toxic waste and has a powerful army.
One idea could be the discovery of a holy relic during the war that both sides believe can give them victory, leading to a race to obtain it. Another could be the emergence of a holy figure who tries to bring peace in the midst of the chaos of the world war.
One interesting plot could be a group of civilians forming a resistance against an occupying force during World War 3. They might use guerilla tactics and their knowledge of the local terrain to fight back.
Another good one for World War 2 is 'Slaughterhouse - Five' by Kurt Vonnegut. It's a semi - autobiographical novel that jumps around in time and space. It shows the absurdity of war through the experiences of Billy Pilgrim, a soldier who becomes 'unstuck in time'.