Well, in a 'sunken wreckage rwby fanfic', it could be that the sunken wreckage is an old airship from a long - forgotten battle. The RWBY team stumbles upon it while on a journey. Inside the wreckage, they discover secrets about the past of Remnant. There could be old recordings or documents that shed light on some long - lost knowledge. They also have to deal with the unstable structure of the wreckage as they search for these secrets.
Ruby could be one of the main characters. Given her adventurous spirit, she would be eager to explore the sunken wreckage. Weiss might also be there, using her glyphs to help the team navigate through the difficult underwater environment. Blake could be important too, her stealth skills helping to detect any hidden dangers within the wreckage.
Well, a really exciting plot might involve Percy getting trapped in a parallel dimension within the Venator world. He could discover new powers there that are unique to that place. And perhaps there's a prophecy in the Venator world that Percy is a key part of, which would lead to him having to go on a dangerous quest to fulfill it. Also, he could meet a group of Venator characters who initially distrust him but later become his friends as they realize they share a common enemy.
A Venator wizard who can manipulate time could be an interesting addition. He could help Percy in his quests by using his time - manipulation powers to gain an advantage. Another could be a half - Venator, half - demigod character who is conflicted about which world to side with.
It could be something like whether justice always prevails or if fate can be changed. Or perhaps it's focused on the internal conflicts of the main character and their growth.
The novel might feature themes such as family bonds, coming of age, or the pursuit of dreams. These themes give depth to the characters and the story as a whole.