Well, the races are very different. In Star Trek, you have the Federation races like Humans, Vulcans, and Klingons. They generally have a more diplomatic approach. In Warhammer 40k, races like the Orks are just out for a good fight all the time. So in a crossover, the Orks might see the Klingons as kindred spirits in a way, but the Klingons would probably be put off by the Orks' lack of honor.
One interesting concept could be the clash of different ideologies. In Warhammer 40k, there is a lot of grimdark and a strict hierarchy, while Star Trek is more about exploration and unity. So seeing how characters from both universes react to the other's values can be really engaging.
A lesser - known but very interesting 'Star Trek 2009 Crossover Fanfiction' is 'Star Trek 2009 Meets Firefly'. This one is special because it combines the high - tech future of Star Trek with the scrappy, Western - influenced world of Firefly. The contrast between the two settings makes for a very unique reading experience, and the author does a great job of creating a story that respects both source materials.
In a crossover, the Borg from Star Trek could encounter Skynet. The Borg might see Skynet as a potential source of technology to assimilate. However, Skynet would likely resist assimilation and fight back. This could create a three - way conflict if the humans in the Star Trek universe also see Skynet as a threat and try to take advantage of the Borg - Skynet battle to destroy both.
The cultures in both universes are also ripe for exploration in the crossover. The Federation's values of equality and cooperation in Star Trek contrast with the more hierarchical and often morally ambiguous cultures in Star Wars. A story could focus on how characters from each side learn from or clash with the other's cultural norms.
In a Warhammer Naruto crossover, Naruto's Rasengan would be a very unique ability compared to the magic and melee combat in Warhammer. His ability to quickly form and launch a powerful ball of chakra could be devastating against many Warhammer foes. On the other hand, the Warhammer wizards' large - scale spells would be on a different level than most Naruto jutsus in terms of area - of - effect. For example, a powerful fireball jutsu might be like a small - scale version of a Warhammer fire spell.
The gods in Warhammer 40k are on a whole different level of power. They can warp reality on a galactic scale. In Marvel, the Asgardian gods like Thor have great power, but it's not on the same scale as the Chaos Gods in Warhammer 40k. But if Thor were to face off against a daemon from Warhammer 40k, his lightning and strength might be enough to hold his own, especially if he had the help of some of his Marvel comrades and the technology and weaponry from Warhammer 40k.
A common crossover is the appearance of Starfleet officers in the Warhammer 40k universe. They might be seen as strange and otherworldly beings. Their peaceful exploration ethos would be a sharp contrast to the constant warfare in 40k. For example, they could try to broker peace between warring factions in 40k, which would be a huge challenge given the nature of that universe.
I really like 'TNG and Stargate SG - 1: The Unexpected Encounter'. In this fanfiction, the crew of the Enterprise - D from Star Trek TNG stumbles upon the Stargate. It's a fascinating read as it explores how the two different technologies and cultures would interact. There are some really cool moments where Picard has to negotiate with the Goa'uld, and Data tries to understand the Ancient technology.
One great 'Star Trek DS9 Crossover Fanfiction' is 'DS9 and the Enterprise Crew'. It combines the unique characters from DS9 with the more well - known Enterprise crew in an exciting adventure. The author does a great job of keeping the personalities of all the characters intact while creating a new and engaging story.
Ancient humans in Warhammer 40k fanfic can be very different from modern races. In terms of culture, modern races are often more fragmented and war - like. Ancient humans may have had a more harmonious society. They also might have had different physical capabilities. Maybe they were more resistant to the harshness of space without the need for bulky power armor like the Space Marines.