One interesting fanfiction could be where Saitama from OPM ends up in the world of Attack on Titan. He might just casually punch a Titan's head off with one blow, completely changing the dynamic of the fight against the Titans. It would be a hilarious yet action - packed story.
One idea could be that the Overwatch heroes are transported to the Attack on Titan world. Tracer could use her time - traveling abilities to outmaneuver the Titans. Maybe Reinhardt's shield would be crucial in protecting the Survey Corps from Titan attacks.
Saitama is clearly the most powerful. In the Attack on Titan world, the Titans are a huge threat. But for Saitama, they are just like any other weak opponent. He doesn't even break a sweat dealing with the most powerful threats in his own universe, so the Titans would be no match for him. His power is not only physical but also his unshakable will and his simplicity in approaching any fight. He doesn't get distracted or intimidated, which makes him an unstoppable force in any situation, including in a merged OPM and Attack on Titan universe.
One challenge is combining the two very different universes. Overwatch has a more futuristic, technology - based setting, while Attack on Titan is more medieval - ish with its walled cities and limited technology. So, making the two settings blend together in a believable way can be tough.
Perhaps Eren and his friends from Attack on Titan enter the Unordinary universe and are mistaken for having abilities. They then have to navigate the complex social hierarchy of the Unordinary world while also trying to find a way back to their own world. And the Titans might start showing up in the Unordinary world, causing chaos.
One possible plot could be that the Titans from Attack on Titan are somehow connected to the alien threats in Destiny. The Guardians could be sent to the world of Attack on Titan to investigate the sudden appearance of these giant creatures. They might initially struggle to understand the unique nature of the Titans, which are different from the enemies they usually face. Along the way, they could team up with the Survey Corps, sharing their advanced technology and combat skills. This would lead to some epic battles where the combined forces of Guardians and the Survey Corps fight against the Titans, while also trying to figure out the mystery behind their existence.
One interesting storyline could be where the fanfiction explores an alternate universe where the Titans have a different origin. Maybe they are not just mindless giants but are actually the result of a failed scientific experiment gone wrong in a more complex way than in the original series.
Eren Yeager is likely to be one of the most popular. His complex character arc in the original series makes him a prime candidate for fanfiction exploration. In fanfictions, he might be further developed, perhaps showing different sides of his personality or exploring different paths his character could have taken.
Well, perhaps the titans could be like the animatronics in FNAF. The Survey Corps could be trapped in a titan - infested area that has some strange FNAF - like mechanics. For example, the titans are only active at night and there are 'rules' to avoid them similar to the rules in FNAF games.
One great 'Attack on Titan' fanfiction with a Titan reader is 'Titan's Perspective'. It delves into how a reader - turned - Titan experiences the world within the walls. It offers a unique view of the familiar 'Attack on Titan' universe, exploring the inner thoughts and struggles of a Titan, which is something not often explored in the original series.