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 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.
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.
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.
Armin could be another good character for this. He's intelligent and good at strategizing. In a 'Attack on Titan meets FNAF' fanfiction, he could use his wits to try and understand the nature of the FNAF elements and come up with plans to either avoid or combat the threats that come from the combination of the two universes.
Well, they might have a deep conversation about their different views on the world. Eren could try to convince Zeke of his more radical approach to saving the Eldians, while Zeke might push back with his own ideas of euthanasia for the Eldians. It could be a very tense encounter.