One idea could be that Ben Tennyson's Omnitrix malfunctions while he's in the Avatar world. So, instead of transforming into his usual aliens, he starts taking on the forms of Avatar creatures. For example, he might turn into a flying bison or a waterbender - like spirit. This would create all kinds of chaos and new adventures as he tries to figure out how to control these new forms and also deal with the political and elemental challenges of the Avatar world.
In a crossover fanfiction, the interaction between Ben's powers and the bending in Avatar could also lead to new power - ups or evolutions. Maybe by being exposed to the chi - based bending, some of Ben's alien forms could develop new abilities. For instance, his Swampfire form might gain the ability to control plant - like elements in a more refined way similar to how an earthbender controls plants. And on the other side, benders could learn from Ben's alien forms about different ways of using energy and physical strength, which could lead to new bending techniques.
One idea could be to have the Thundercats arrive in the Avatar world. Maybe they land near a Water Tribe. The Thundercats' advanced technology and unique abilities would be a shock to the Avatar world. Lion - O could form an alliance with Aang. They could learn from each other's leadership styles. The Thundercats could help in the fight against the Fire Nation with their strength and weaponry.
The crossover could start with a strange portal opening between the two worlds. Naruto characters like Sasuke might be intrigued by the bending abilities in the Avatar world. He could try to learn firebending, thinking it could enhance his own fire - based jutsu. And the Avatar characters could be equally fascinated by ninjutsu.
One possible fanfiction could be about Naruto characters finding themselves in the Avatar world. For example, Naruto's determination and never - give - up attitude could be a great addition to the Avatar universe. He might learn bending techniques in a unique way, perhaps by combining his chakra control with the flow of chi in the Avatar world. This could lead to some really interesting battles and character interactions.
First, you need to understand the characters well. Iroh is known for his wisdom, his love for tea, and his complex past. The Avatar, depending on which one you choose to feature, has their own unique set of powers and personalities. Then, think of an interesting premise. It could be something like Iroh getting lost in the Spirit World and meeting the Avatar there. Next, plan your plot. Decide how the characters will interact and what challenges they will face. For example, they might have to work together to defeat a dark spirit.
One idea could be a crossover where Ben 10's Omnitrix malfunctions near Avatar Aang's world. Ben and Aang team up to face a new threat that is causing chaos in both their realms. Maybe some of Ben's alien forms have unexpected interactions with the bending abilities in the Avatar world.
Jon Snow would be an interesting character to be an avatar. Given his complex backstory and his role in the fight against the White Walkers, as an avatar he could gain even more powerful abilities. Maybe he could have the power to control the elements, which would be a huge advantage in battles. He could use this to create blizzards against the White Walkers or to put out fires during the sack of King's Landing.
Well, it could be about a crossover in the Ben 10 universe that involves neglected or overlooked characters or storylines. Maybe it's a fan's attempt to give more spotlight to those parts that the official shows or comics didn't fully explore.
Trudy Chacon can be a really interesting character in Avatar 2009 crossover fanfiction. She's a human who has a certain level of empathy for the Na'vi, and in crossovers, she could play a role in bringing different groups together. Another popular one is Norm Spellman. His scientific knowledge and his own journey in the Avatar world can be explored further in crossovers.