One idea could be that the Titans suddenly appear in modern cities. People have to quickly adapt their defense mechanisms, like using modern military equipment against them. Another could be that the Survey Corps' technology is somehow transferred to our world, and we see how modern scientists study and improve it.
To make your 'AOT in our world' fanfic stand out, focus on character development. Take the AOT characters and put them in situations that force them to change according to our world's values. For example, Levi, who is used to a strict military hierarchy in AOT, could struggle with the more democratic and free - spirited nature of our modern society. You could also introduce new characters from our world who have unique abilities or knowledge that can help or hinder the AOT characters in dealing with the Titan threat.
Animals novel can humanize animals. For example, in 'The Call of the Wild', we see Buck's thoughts and feelings, which makes us view dogs not just as pets but as complex beings with their own desires and instincts.
It's fairly common. Fans often look for more content related to their favorite shows. Since 'Attack on Titan' has a large and passionate fan base, there are a lot of fanfics available. 'Aot' fans might watch (read) these fanfics to explore different scenarios that the official story didn't cover. For example, they might want to see how a certain character would react in a different situation or what would happen if a major plot event had a different outcome.
Some animals might be scared. After all, humans are so different from them. But some brave ones, like the fox, might be curious and want to interact. For instance, a fox might see the human as a potential business opportunity or just be interested in the new things the human has.
In Pokemon world fanfic, animals can be quite different from real - world ones. For example, they might co - exist with Pokemon in unique ways. Some fanfics may show animals having special abilities or a symbiotic relationship with Pokemon. They could also have adapted to the fantastical environments in the Pokemon world, which often feature strange plants and otherworldly landscapes.
Once upon a time, there was a little squirrel. It was a very friendly animal. It made friends with a little boy. The squirrel would often come to the boy's window and wait for him to offer some nuts. They played together in the forest. The boy protected the squirrel from other big animals, and the squirrel in return showed the boy where the most beautiful flowers were in the forest. It was a really wonderful friendship between them.