One idea could be that Ladybug and Chat Noir face a villain who can manipulate time in the future. This would force them to not only fight in the present but also find a way to prevent the villain from causing chaos in the future. Another plot could involve a new Miraculous holder from the future coming back to help them in their present battles, bringing with them new powers and a different perspective on their fight against evil.
One idea could be that Hawk Moth finally manages to get hold of both the Ladybug and Cat Miraculouses and the heroes have to find a new way to fight him, perhaps by teaming up with some of the minor characters who develop new powers. Another could be that Ladybug and Cat Noir have to travel to the future to stop an even greater threat that is related to Hawk Moth's actions in their present time.
One idea could be exploring an alternate ending where the characters find a way to break free from the game's cycle without any deaths. Another could be a story focused on the backstories of the characters that were not fully explored in the original, like how they ended up in the situation of the game in the first place.
A possible plot in the fanfiction could be a time - travel twist. What if a character goes back in time to prevent the events of 'Danganronpa Watch the Future' from ever happening? This would change the entire dynamic of the story and relationships between characters. Or, the fanfic could focus on a romance that was only hinted at in the original. It could develop the relationship between two characters who had a lot of unspoken chemistry.
Maybe in this fanfiction, The Flash watches a future where Central City is in ruins because of a new type of meta - human threat that he has never faced before. So he starts training in the present to develop new powers or techniques to be able to combat this future threat. He could also try to find and recruit other meta - humans who might be able to help him in the future fight.
One plot idea could be that Ladybug and Chat Noir see a future where Paris is in ruins because they failed to stop Hawk Moth. This would give them the motivation to find a new strategy in the present, like seeking out new allies or uncovering a hidden power of their Miraculouses.
Perhaps in the 'Steven Universe Watch the Future fanfiction', there could be a plot where Steven travels to a different dimension within the Gem universe. In this dimension, the rules are different, and he has to adapt quickly. He meets alternate versions of his friends who have different personalities or powers. This could lead to a self - discovery journey for Steven as he sees how different choices could have led to different outcomes. He then has to find a way to bring back something from this dimension that can help save his own world from a brewing disaster.
One idea could be a story where the Peacock Miraculous has a unique malfunction that causes it to create unexpected akumas. For example, instead of creating the usual villains, it creates akumas that have the power to spread positive emotions but in a chaotic way that still disrupts Paris. Another idea is a fanfiction where the holder of the Peacock Miraculous has to team up with Ladybug and Chat Noir to fight against an ancient evil that is specifically drawn to the power of the Peacock. This could involve exploring the history of the Miraculous and its connection to this new threat.
One idea could be a crossover where the Miraculous heroes and Ben 10 team up to fight a common enemy. Maybe an alien villain that is immune to the powers of the Miraculous but Ben's alien forms can counter. Another could be a situation where Ladybug's Lucky Charm combines with one of Ben's alien gadgets to create a super - weapon. And a third could be a story where Ben gets akumatized and the Miraculous heroes have to figure out how to save him without using brute force as his alien forms are very powerful.
One idea could be Multimouse getting lost in an alternate dimension where the rules of the Miraculous are different. She has to figure out how to use her powers in new ways to get back home.
One idea could be that the Miraculous Phoenix has the power to heal not only physical wounds but also emotional traumas. The story could follow a character who is deeply scarred by past events and is chosen by the Phoenix Miraculous. As they learn to use its powers, they gradually heal themselves and those around them.