I'm not entirely sure specifically as there could be many different takes on it. It might be a fanfiction related to Breath of the Wild (BotW) where the characters are somehow watching the future. Maybe it involves Link or Zelda having visions of what's to come in the game's world.
You can start by looking on popular fanfiction websites such as Archive of Our Own (AO3). They have a large collection of Breath of the Wild fanfictions and you might be able to find this one by using the search function with the exact title or relevant keywords.
In most cases, watching (reading) fanfiction is legal as long as it doesn't violate copyright laws in a major way. Fanfiction is often a derivative work, and as long as it's not being sold commercially without permission from the original copyright holder and is more of a non - profit creative exploration of existing works, it's usually okay.
I think Levi could benefit as well. His combat skills are already top - notch, but seeing the future could help him anticipate enemy attacks even better. He could train his squad more effectively based on the future battles he witnesses, ensuring their survival and making them even more formidable against the Titans.
Some popular platforms for fanfiction in general could be Archive of Our Own (AO3). It has a vast collection of various types of fanfiction, including those with futuristic themes. Another one could be FanFiction.net, which also hosts a large number of stories. Wattpad might also have some future - themed fanfiction, although it has a broader range of content.
I'm not sure specifically as there could be many different interpretations in such a fanfiction. It might be about the members of BTS observing possible future scenarios, perhaps related to their careers, relationships, or the world in general.
Some of them might be shocked. Tony Stark, for instance, might immediately start thinking of ways to use technology to change what he saw. Steve Rogers would probably be more concerned about the moral implications of interfering with the future.
There might be an old sage - like character who has a vast store of memories and uses them to mentor the younger characters in dealing with the future. They could provide wisdom based on past events and how they might repeat or change in the future.
In 'Watching the Future Arrow Fanfiction', a prevalent theme is technology. Since it's set in the future, there are often new and advanced technologies that the characters have to deal with. This could be new weapons or surveillance systems. Also, the theme of family and friendship is common. New relationships are formed, and old ones are tested as the story progresses in this future setting. For example, the children of the original characters might have to deal with the legacy of their parents while also forging their own paths. It adds a lot of depth to the story.
One possible plot could be Naruto seeing a future where his friends are in danger. So, he starts training harder in the present to prevent that future from happening. He might see a powerful enemy that his friends can't defeat alone, and this knowledge gives him the motivation to gain new powers or improve his existing skills.