A God of War and Assassin's Creed crossover fanfic could be really cool. Picture Kratos in the world of Assassin's Creed, with his brute strength and combat skills clashing or collaborating with the assassins' stealth and parkour abilities. He might be on a quest that somehow intersects with the Assassin's Creed's fight against the Templars.
Another idea is a crossover with the Legend of Zelda series. Kratos could find himself in Hyrule. He might not understand the magic and creatures there at first. But his determination and combat prowess would make for an interesting dynamic as he interacts with Link, Zelda, and faces off against Ganon. This could be a really unique take on both franchises.
One idea could be a crossover with Norse mythology outside of the God of War series. For example, Kratos could meet Thor from the original Norse tales. Another could be a crossover with Greek and Roman mythology, where Kratos encounters some of the forgotten or lesser - known Roman gods. Maybe a crossover with a popular fantasy world like Middle - earth, and Kratos has to face off against some of the powerful beings there.
A crossover with another popular action - adventure game like 'The Witcher'. Geralt and Kratos could meet in a world that is a blend of their two universes. They might initially be at odds due to their different moral compasses, but then find common ground in fighting a powerful, otherworldly enemy that neither could defeat alone. This would create an interesting dynamic between their combat styles and personalities.
A God of War 4 crossover fanfiction could involve crossing over with the DC universe. Kratos could find himself in Gotham City and have to deal with the likes of the Joker and Batman. His no - nonsense attitude and brute strength would be a contrast to the more morally complex characters in the DC world. Or perhaps a crossover with the Legend of Zelda series, where Kratos and Link could exchange combat techniques and embark on a joint adventure.
One interesting idea could be a crossover with other mythologies. For example, Kratos from God of War meeting Thor from Norse mythology in a different context than the official games. This could lead to epic battles and exchanges of power and wisdom.
Well, for 'god of war atreus crossover fanfiction', you could do a crossover with other video game characters. Say, Atreus meets Link from The Legend of Zelda. Link could teach Atreus some of his unique combat skills, and they could go on a quest together in a merged world of Hyrule and the God of War world. Or, a crossover with Assassin's Creed. Atreus might get involved with the Assassins and Templars' conflict, learning about their different ideologies. And then there's the idea of a crossover with Final Fantasy. He could encounter a group of summoners and learn about their magic system.
One idea could be to have the characters from Gears face the same kind of epic battles as in God of War. For example, the COG soldiers could find themselves in a world full of Greek mythology elements. Maybe they have to fight alongside Kratos against some new, powerful monsters that are a mix of the grotesque creatures from Gears and the mythological beasts from God of War.
One idea could be a crossover with the Halo universe. Imagine the COG soldiers teaming up with Spartans to fight a common enemy that threatens both their worlds. They could share their combat strategies and technologies, like the Lancer's chainsaw bayonet with the Halo's energy weapons.
One idea could be to have the ponies from MLP enter the world of God of War. They could team up with Kratos and use their unique magical abilities to fight the gods. For example, Twilight Sparkle's powerful magic could be used to counter some of the dark magic of the God of War enemies.
One idea could be exploring Kratos' relationship with his son in more depth. Maybe show them facing a new, unexpected threat together and how they grow closer through it.
One idea could be to focus on the backstory of a minor god in the Total War universe. Explore how they came to be and their early struggles. For example, you could write about a god of a small tribe who has to prove their worth against more powerful deities.