One popular one could be a crossover with a science - fiction universe like 'Star Wars'. Picture a US Marine finding themselves in the middle of a galactic battle. They'd bring their combat skills and military discipline to the chaotic world of lightsabers and spaceships.
First, decide on the two universes you want to cross over. If it's the US Marines and, say, a fantasy world of elves and magic. Then, think of a plot device to bring them together, like a magical portal opening up in a Marine base.
Another scenario could be that a Marine has some sort of special ability that is related to the chakra system in Naruto. This Marine could be sent to the Naruto world to study their way of using chakra. Along the way, he meets Naruto and they form an unlikely friendship. Naruto could teach him more about chakra control, and the Marine could introduce Naruto to some modern military strategies.
A possible plot could be a battle. The US Marines might be facing a threat in their world that has some similarities to the powerful enemies in the Naruto universe. So, they seek help from Naruto and his friends. Naruto, with his Rasengan and other jutsu, could join the Marines in the fight against the common enemy.
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.
Yes. There could be a fanfiction where a US Marine accidentally stumbles into the wizarding world through a portal. He meets Harry Potter, who is in the middle of a conflict with a new dark force. The Marine's knowledge of modern warfare and technology helps Harry in devising new strategies to fight the enemy. The unique part could be how the two different worlds' elements, like magic spells and military equipment, are combined in the battle scenes.
During the Korean War, a group of US Marines were surrounded by the enemy. They refused to surrender. Instead, they fought with all their might. They fought through the night, and their fierce resistance made the enemy think twice about attacking them further. In the end, they were rescued, but their story of standing their ground against all odds became a symbol of heroism in the US Marine Corps.
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.
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.
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.