One possible plot could be that the characters face a new, more powerful type of Grimm that has abilities they've never seen before. They have to quickly adapt and find new ways to fight. Maybe Ruby discovers a new form of her scythe's power to combat this threat.
It could be that Ruby has to deal with the consequences of a major decision she made in the past. This causes her to question her leadership skills and she embarks on a journey of self - discovery to become a better leader for her team.
Well, it could involve the characters seeing different versions of their future selves. Maybe they see themselves achieving great power or facing great tragedies. They might then try to change the course of events based on what they've seen.
Well, it could involve the RWBY characters seeing future versions of themselves. Maybe they see how their relationships have evolved or how their combat skills have improved. They might also witness future threats to Remnant and start preparing for them in the present.
A powerful sorcerer could be the main villain. This sorcerer has the ability to control minds and is using it to turn some of the Huntsmen and Huntresses against their comrades. He aims to take over Remnant and rule with an iron fist.
Well, it could be about a world where technology has advanced to the point that humans can teleport at will. The main character, a young scientist, discovers a flaw in this system that could lead to the destruction of the universe. So, he embarks on a journey to fix it.
In 'naruto in the future fanfiction', perhaps Naruto has passed on his ninja way to a new generation. His son or disciple could be facing a new threat that combines old and new jutsu. Maybe they have to deal with a group that has found a way to use ancient, dark jutsu in a modern, technological world.
The 'Relic of the Future' in RWBY fanfiction is likely a plot device. It could be something that ties into the existing lore of RWBY, like the other relics in the official story. Maybe it has a connection to time, allowing characters to glimpse or even influence the future. It could also be a relic that is prophesied to play a major role in a future conflict or the salvation of Remnant, the world in RWBY.
It could develop with the RWBY characters slowly accepting or rejecting the future they see. Maybe they try to change it if it's a bad future.
Maybe it could be about Cardin trying to hide his Faunus identity at first. He might struggle with the discrimination that Faunus face in the RWBY world while also dealing with his own personal growth and relationships within the team or at school.
Maybe it's about Ren preparing a special meal for his friends in RWBY. He could be using his skills to cook something that gives them strength for their battles, like a dish made with Dust - infused ingredients.