One unique plot idea could be that the OC has a special connection with the owl - dragon hybrid. Maybe it can communicate with it telepathically and they team up to uncover secrets about the Titans that no one else knows. For example, they might find out that the Titans are being controlled by an ancient force related to the owl - dragon's origin.
Perhaps the owl - dragon in the fanfic has the ability to transform the OC into a powerful form that can fight Titans more effectively. However, this transformation comes with a price. Each time the OC transforms, they lose a bit of their humanity. The story could revolve around the OC's struggle to balance using this power to protect their loved ones and the world against the Titans while also trying to retain their humanity.
A cool plot idea would be if the OC in the fanfic was initially feared because of their association with the owl - dragon. But as the story progresses, it's revealed that the owl - dragon is actually a key to saving the world from the Titans. The OC has to convince the other characters of this fact while also facing challenges from those who want to use the owl - dragon for their own evil purposes.
One idea could be an OC who is a Titan Shifter with a unique ability like being able to control the elements while in Titan form. For example, they could create ice storms or fire blasts. Another could be an OC who has to struggle with the morality of being a Titan Shifter in a world where Titans are seen as pure evil. They might try to find a way to coexist with the other humans instead of just fighting Titans.
To develop the OC in the Attack on Titan OC Owl Dragon Fanfic, they could start as an outcast because of their connection to the strange owl - dragon. As they journey with the owl - dragon, they encounter different situations. They might meet other characters who initially reject them but later come to accept them. This would help the OC grow in terms of self - acceptance and understanding of others. They could also develop skills like flying on the owl - dragon's back, which would boost their confidence and change their view of themselves as a capable fighter against the Titans.
The plot could involve a conflict within the group of titan shifters because of the tenth titan. Some might see it as a threat, while others believe it's the solution to end the war. The tenth titan's power could be something that disrupts the balance between the different factions. For example, it could have the ability to nullify the powers of other titans, which would make it a highly sought - after and dangerous power.
Many 'Attack on Titan Godzilla fanfic' are unique in their character interactions. For example, how Eren Jaeger might react to Godzilla. Does he see Godzilla as a tool to defeat the Titans, or is he afraid of this new, uncontrollable force? These fanfics can really expand on the characters' personalities and relationships in unexpected ways.
You can start by mixing the lore of both. For instance, the Titans' origin story could be linked to the Kaiju's in some way. Maybe the same source of power or experiment created both. This would add a new layer of mystery and connection to the plot.
Another plot idea is that there's a secret group within the Naruto universe that has been experimenting with Titan shifting, and Naruto accidentally gets involved. He then has to figure out how to control this new power while also dealing with the group that wants to use it for evil. Maybe he discovers that some of his friends are also unknowingly part of this experiment, and he has to save them.
A great idea for an 'Attack on Titan' permanent titan fanfic would be to focus on the relationship between a permanent titan and a human. It could be a story of an unlikely friendship or a situation where the human is trying to study the titan to gain some sort of advantage in the fight against the other titans. The fanfic could also delve into the emotional and psychological aspects of the titan, if it has any remnants of its former human self, and how it copes with its existence.
A great plot for such a fanfic could be that Mikasa's Titan form is a result of a connection to an ancient Titan power. As she becomes a Titan, she starts to have visions of the past, of how the Titans came to be. She then decides to use this knowledge and her new form to try and end the Titan - human conflict once and for all. Along the way, she has to face her friends who are initially scared of her but eventually come to accept her new form as she proves that she is still the same Mikasa deep down, just in a different body.
One interesting plot idea could be about a group of modern - day people suddenly finding themselves in a world similar to that of Attack on Titan. They have to quickly learn the skills of survival, like using the 3D maneuver gear which they discover in an abandoned military base. Another could be a fanfic where the Titans exist in a parallel modern world, and a secret organization has been fighting them in the shadows all along.
One idea could be exploring an alternate world where the Titans have different abilities. For example, some Titans might be able to fly or control the elements. Another plot could revolve around the characters from the original 'Attack on Titan' being transported to a completely different world with its own set of rules and threats. Maybe in this new world, the Survey Corps has to form alliances with strange new creatures to fight against a common enemy.