Yes, unfortunately, Hange met their end in the manga. It was a poignant moment for fans. The circumstances leading to their death were quite intense and had a significant impact on the story.
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.
Well, in the fanfic, Bruce would probably become more withdrawn. He'd brood over Jason's death, questioning his methods and his role as a mentor. Dick would be angry at the world, especially at the villains who might have been involved. Tim, on the other hand, would be more determined to prove that he can be a worthy Robin, but also carry the pain of losing Jason. Alfred would be the one constant, trying to comfort everyone with his wisdom and care. It's a really tragic event for the Batfamily and their reactions would be complex and full of emotions.
The guild would be devastated. Natsu would probably be one of the first to be enraged. He'd vow to find whoever or whatever was responsible and make them pay. His fire would burn hotter than ever as he channels his anger.