There could be a story where the nomadic tribes in 'Game of Thrones' are compared to the migratory animals on 'Planet Earth'. The Dothraki, for example, could be paralleled with wildebeests on their great migrations, and their cultures and survival strategies could be explored in relation to each other.
In some fanfiction, the powerful magic in 'Game of Thrones' could be used to protect the endangered species on 'Planet Earth'. For instance, a wizard from Westeros could use spells to safeguard the pandas in China or the polar bears in the Arctic. It would be a unique way to combine the two universes.
A possible crossover could be Ultron taking over the body of a White Walker. This would give him control over the undead army and a terrifying presence in the North of Westeros.
There might be a fanfiction where the dragons in 'Game of Thrones' interact with the unique wildlife on 'Planet Earth' as if they were exploring new territories. It could be a really exciting concept, with the dragons flying over the African savannah or above the rainforests, causing a stir among the animals.
One interesting crossover could be the Avengers having to deal with the political intrigue of Westeros. For example, Iron Man might use his technology to try and outwit the various lords vying for the Iron Throne, much like he does with his corporate rivals. Another could be Thor interacting with the gods in the Game of Thrones universe, perhaps recognizing some similarities between their powers.
One great crossover could be a scenario where the dragons from 'Game of Thrones' are used in the battles of Middle - earth in 'Lotr'. For example, imagine Smaug - like dragons fighting alongside the orcs against the free peoples. Another interesting idea is to have characters from the two universes meet. Maybe Arya Stark could end up in Middle - earth and learn some of the elvish skills in combat and stealth. There could also be a crossover where the magic systems interact, like the wizards in 'Lotr' trying to understand the power of the White Walkers in 'Game of Thrones'.
A great crossover could involve the ninja clans of Naruto in the world of Game of Thrones. The Uchiha clan's Sharingan ability might be compared to the prophetic dreams some characters in Game of Thrones have. Maybe the Uchiha could use their powers to foresee battles or political upheavals. And the Hyuga clan's Byakugan could be used for surveillance in the castles and cities of Westeros, much like how the maesters keep an eye on things. Also, the concept of chakra could be introduced to the world of Game of Thrones, where it might be seen as a new form of magic.
One interesting crossover could be a scenario where the powerful vampires from The Originals find themselves in the political intrigue of Westeros from Game of Thrones. Maybe they get involved in the power struggles between the different houses, using their vampiric abilities to gain an edge. For example, Klaus Mikaelson could try to manipulate Cersei Lannister for his own ends.
One interesting crossover is when Ben's aliens interact with the dragons in Game of Thrones. For instance, Ben's Upgrade form could potentially bond with a dragon, creating a super - powered dragon - like creature. It's a really cool concept.
A really cool fanfiction idea could be that the ancient prophecies in both Eragon and Game of Thrones are somehow related. Characters from both stories start to realize that their fates are intertwined due to these prophecies. This could lead to a grand adventure where they have to work together to fulfill or prevent the prophecies from coming true. For instance, Daenerys Targaryen and Eragon could join forces, with their dragons, to face a great evil that has been foretold in both of their worlds' prophecies.
A great crossover idea in the fanfiction could be the magic systems. Imagine Daenerys Targaryen learning about the Signs that Geralt uses. Her dragons could be intrigued by the magic of The Witcher world, and perhaps they could interact in ways that are both unexpected and exciting. This could lead to new alliances or battles depending on how the story unfolds.
A really interesting crossover could be where the Eva pilots are inserted into the Game of Thrones world as special protectors. They use their piloting skills and combat abilities to protect a particular house or kingdom. For example, Rei could be a mysterious figure protecting the Night's Watch, with her calm and stoic nature fitting well into that cold and desolate place.