A great way to blend them is through the plot. Have a shared goal or threat that affects both the RWBY universe and the German Empire. This could be a powerful magical or technological artifact that has the potential to disrupt both worlds. Then, have characters from both settings interact in pursuit of this goal. They can learn from each other's skills and knowledge. For instance, the RWBY characters can learn about traditional German combat techniques, while the German Empire soldiers can learn about using Dust. This exchange of ideas and skills will help blend the two settings more organically.
The RWBY and Naruto universes can be blended well in fanfiction by having the characters share their skills. For instance, Yang's strength could be combined with Naruto's Rasengan for a super - powerful attack. Also, the different settings can be merged, like having the Hidden Leaf Village exist in the same world as Vale.
Well, you could start by having a common threat that affects both universes. For example, a powerful entity that can control both the Grimm in RWBY and the Xenomorphs. This would force the RWBY characters and any survivors in the Xenomorph universe to work together.
Well, the architecture and overall feel of the 'Helter Skelter' world could be incorporated into the Hidden Villages. For instance, some parts of a village could have the dark, dilapidated look of 'Helter Skelter' areas, while still maintaining the ninja - style functionality. This would create a really unique and visually interesting setting.
In a crossover fanfiction, the settings can be blended by having a shared resource. Let's say there is a rare mineral. In the Firefly universe, it's needed to upgrade their engines for better speed and efficiency. In the castle world, it's used for some magical spells or to strengthen their defenses. So, both the Firefly crew and the castle's people are in a race to find this mineral. This brings the two settings together as they explore each other's territories in search of it.
The worlds can be blended by introducing Gundam technology into RWBY. For instance, RWBY's Beacon Academy could start a new program to train students in Gundam piloting. Or, the Grimm could be a threat to the Gundam universes as well, leading to a united front between RWBY and Gundam forces.
Well, you can start by having the settings interact. For instance, the forest in 'Into the Woods' could connect to the forested areas around Forks in 'Twilight'. The characters' traits can also be combined. The vampires' elegance and strength in 'Twilight' could be paired with the cunning of some 'Into the Woods' characters like the fox. Also, the magical elements from 'Into the Woods' like spells and wishes could influence the events in the 'Twilight' universe.
One way is through character interactions. For example, Shepard could team up with Ruby and they could share their combat experiences. Shepard's military training from Mass Effect and Ruby's Huntsman skills from RWBY could create interesting battle strategies. Another aspect could be the technology transfer. Maybe the advanced tech in Mass Effect like biotics could be introduced to RWBY's world, causing a stir among the characters there. Also, the cultural differences between the two universes could lead to some great storylines. The more rigid military structure in Mass Effect compared to the more free - flowing world of RWBY could lead to clashes and reconciliations.
One idea could be to have the RWBY characters time - travel to the German Empire era. They could interact with the historical figures and get involved in the political and social situations of that time. For example, Ruby could meet with the military leaders and learn about their strategies, while Weiss might be intrigued by the upper - class society and their etiquettes.
The cultures of the two worlds could be explored in the fanfiction. The hierarchical society in RWBY with the Huntsmen and Huntresses could interact with the monarchy and different social classes in Final Fantasy 15. This could lead to political intrigue and new storylines as characters from both worlds try to understand and adapt to each other's cultures.
By mixing the unique abilities. Naruto's ability to use chakra can be related to the energy sources in Gundam. For instance, chakra could be used to power up a Gundam's special attacks.