One idea could be that the Horsemen from DarkSiders end up in the world of RWBY. Maybe War arrives first and is mistaken for a powerful Grimm. He then has to figure out how to interact with the Huntsmen and Huntresses while also trying to find a way back to his own realm. Another idea is that the characters from RWBY somehow stumble into the post - apocalyptic world of DarkSiders and have to adapt to the harsher and more dangerous environment.
Another interesting concept for a Darksiders War crossover fanfiction could be a crossover with the Diablo series. Imagine the dark and gritty world of Diablo mixing with the post - apocalyptic world of Darksiders. The heroes from Darksiders could be lured into the world of Sanctuary in Diablo, where they have to deal with the hordes of demons while also trying to find a way back home.
Another possibility is a crossover with 'God of War'. Death and Kratos could meet. Given their both powerful and somewhat vengeful natures, they could either become bitter enemies or reluctant allies. The story could explore their different views on death, with Death being an embodiment of it and Kratos having a very personal and violent relationship with death in his own journey.
One interesting idea could be a crossover of different timelines within RWBY. For example, characters from the past meet the current ones and have to deal with the differences in their worlds. Another could be a crossover of different teams in unexpected ways, like Team RWBY having to team up with a rival team to face a common enemy that is more powerful than any they've faced before. And sometimes, there are crossovers that involve alternate versions of the characters, where their personalities or abilities are slightly different, which can lead to very unique and engaging storylines.
One idea could be that Naruto is somehow transported to the Darksiders universe. He might initially be confused by the dark and desolate landscape. But with his ninja skills and determination, he could start to explore and try to find a way back home. He could encounter the Horsemen and at first be seen as an enemy, but later they realize he has no malicious intent.
Another plot could involve a crossover within the Darksiders universe. Maybe the Horsemen have to team up with a previously unknown group of characters to face a new, greater threat. This could introduce new dynamics and relationships.
One idea could be a crossover where the characters from Naruto end up in the Darksiders universe and have to fight the demons there using their ninja skills. For example, Naruto could use his shadow clones to confuse the hordes of demons while Sasuke uses his Sharingan to predict their moves.
One idea could be creating an OC who is a hybrid of different races in the Darksiders universe. For example, a half - angel, half - demon character. This would bring a unique perspective as they struggle with their dual nature, being neither fully accepted by the angels nor the demons.
One interesting idea could be the unique character interactions. For example, how the RWBY characters might interact with the denizens of 'heaven' in this fanfiction. Maybe they learn new skills or gain different perspectives on their own world.
One idea could be that Superman arrives in the RWBY world and has to learn about Dust and its powers. He could team up with Team RWBY to fight a common enemy, like a powerful Grimm that is immune to normal attacks but not to Superman's strength. Another idea is that Ruby discovers she has some Kryptonian-like abilities and Superman helps her understand and control them.
One idea could be to cross RWBY characters with characters from another popular anime, like Naruto. Imagine Ruby with the ability to use Naruto's shadow clone jutsu. Another could be a crossover with the Harry Potter universe, where the RWBY characters attend Hogwarts and have to deal with magic and dark wizards. Or perhaps a crossover with the DC universe, with RWBY characters teaming up with the Justice League to save Remnant from a greater threat.