Well, a cool space marine crossover fanfiction idea could involve crossing them with superheroes. Picture a space marine teaming up with Superman to fight an intergalactic threat. Or perhaps a crossover with the Predator universe. The space marines' combat skills and high - tech gear against the Predator's hunting skills would make for an exciting story. Also, a crossover with the Warhammer Fantasy world, bringing the space marines into a world of magic and medieval - like warfare.
Some good ideas for space marine crossover fanfiction are crossovers with time - traveling concepts. For example, space marines getting sent back in time to a pre - industrial era and having to deal with primitive weapons while still using their advanced knowledge. Another idea is a crossover with a Lovecraftian horror universe. The space marines facing off against the eldritch abominations of Lovecraft's world would be intense. And a crossover with a cyberpunk world, where they interact with hackers, augmented humans and mega - corporations.
One idea could be a crossover with the Warhammer 40K Imperium forces where a group of Chaos Space Marines infiltrate an Imperial stronghold. They could face off against Space Marines of the Ultramarines chapter, leading to intense battles and moral dilemmas for both sides. Another idea is a crossover with a fantasy setting like the Elder Scrolls. The Chaos Space Marines could find themselves in Tamriel, causing chaos among the different races and factions there. They might encounter the powerful mages or the warrior guilds.
One interesting concept could be the combination of different power sets. For example, a space marine's combat skills combined with the dreadnought's heavy firepower in unique battle scenarios. Another might be the exploration of the relationship between a space marine who is transferred into a dreadnought and how they adapt to their new form.
One idea could be a crossover with the Alien franchise. Picture Isaac Clarke in a derelict Alien ship, facing both Necromorphs and Xenomorphs. The different types of terrifying creatures could create a really intense and unique horror scenario.
One idea could be a crossover with 'Rick and Morty'. Gary could team up with Rick and they'd have some wild adventures across different dimensions. Maybe they'd encounter some new alien species together that are a combination of the creatures from both shows.
One idea could be a crossover with Star Trek. The Yamato crew could encounter the USS Enterprise and have to work together to face a common enemy, like a powerful alien race that is threatening both their galaxies. They might have to learn from each other's technology and ways of handling situations.
One idea could be that they are forced to team up during a chaos invasion. The Battle Sister's faith and the Space Marine's combat skills complement each other as they fight hordes of daemons. Maybe they start off distrusting each other, but as the battle rages on, they learn to respect and rely on one another.
One interesting idea could be a crossover with "Moana". Elsa's ice powers and Moana's connection to the ocean could create a really cool dynamic. Maybe Elsa accidentally freezes part of Moana's ocean and they have to work together to fix it. Another could be with "Tangled". Rapunzel's long hair and her adventurous spirit combined with Elsa and Anna's journey in Frozen 2 would be exciting. Rapunzel could use her hair to help them climb mountains or cross chasms. A third idea is a crossover with "Beauty and the Beast". Belle's love for books and knowledge could help Elsa understand more about her powers and the history of magic in the Frozen world.
One interesting Space Marine short story could be about a lone Space Marine's battle against a horde of xenos on a desolate planet. He uses his combat skills and strategic thinking to hold his ground until reinforcements arrive.
One idea could be that the Royal Marines are called in to help Hogwarts during a major attack. They use their military tactics along with magic to fend off the dark forces. Maybe they train the students in some non - magical combat skills too.
To start writing a space marine crossover fanfiction, begin with research. Learn about the space marines' lore, their capabilities, and their culture. Then, choose the other element for the crossover, like a magical realm. After that, think about the conflict. It could be a battle for resources or a fight against an evil force that spans both universes. Outline your story, including the beginning, middle and end, and start writing, focusing on making the crossover elements blend well.