Well, they might be shocked at how much technology has advanced in the future depicted in the fanfiction. Maybe there are new types of elemental powers or different ways of training ninjas. It could also be that the relationships between characters have changed in unexpected ways, and they would have to come to terms with that.
They might gain a new perspective on their own abilities. If the future fanfiction shows ninjas with enhanced powers, the past characters could start to think about how they could develop their skills further. For example, if in the future they can combine elemental powers in new ways, the past ninjas might start experimenting.
I don't know who xqc is in this context without more details. It could be someone's username, a streamer, or just a name given to a character in a particular situation.
I'm not entirely sure specifically what 'xqc reacts to neuro story' is about without more context. It could be that xqc, perhaps a person or a character, is reacting to a story that has something to do with the neuro (which could potentially refer to neuroscience, neural networks, or something related to the nervous system in a more general sense).
One popular 'Overwatch Reacts' fanfiction could be the ones where the Overwatch characters react to different timelines or alternate universes. For example, they might react to a world where the Omnic Crisis was never resolved. Another could be their reactions to new heroes joining the team. It's all about exploring the characters' personalities through these reaction scenarios.
Some Tumblr blogs are dedicated to sharing and promoting AOT fanfictions, including the reacts ones. You can search for relevant tags like #AOTreactsfanfiction on Tumblr. Also, Reddit has some subreddits dedicated to AOT. You might be able to find links to AOT reacts fanfictions in the posts or comments there.
One interesting story could be about the characters' reactions to different timelines. For example, Sans might react in a unique way when faced with a timeline where everyone is overly aggressive. Another could be the reactions of the monsters to human technology that they've never seen before, like a smartphone. And there could also be stories about how the characters react to fan - made scenarios, such as a 'what if' situation where Asriel didn't turn into Flowey.
Well, they might be really confused at first. The cultures and settings in Earth fanfictions are so different from their own world in RWBY. For example, if the fanfiction involves modern technology like cars or cell phones, which don't exist in their world, they'd be super curious and might have a hard time understanding how these things work. They could also be shocked by different social norms or historical events that are unique to Earth.
Some MHA reacts fanfiction focuses on the characters reacting to fan - made scenarios. For instance, they could react to a 'what if' situation like All Might never losing his power. This can show how the relationships and the overall story dynamics would change in such a scenario, and it's really fascinating to see the characters' responses.