Perhaps a plot twist where the rules of the King's Game are suddenly changed in a way that no one expected. For example, instead of the normal tasks, the 'King' has to perform a task that endangers themselves. This would flip the power dynamic and create a whole new set of challenges for the characters.
Well, a really cool plot twist might be that the villains from the first playthrough are somehow aware of the New Game Plus. They could start devising new plans to counter the protagonist's knowledge. It could also be that a previously minor character becomes a major antagonist in the New Game Plus. In the fanfiction world, the possibilities are endless. You could also have a twist where the Velvet Room attendants have different roles or abilities, which would greatly impact the protagonist's journey.
Perhaps the person who initiates the time travel isn't who they seem. It could be an imposter who has their own motives for changing the past, like a Shadow in disguise. This would add a whole new layer of mystery and danger to the story.
One idea could be exploring the characters' new lives in the real world after the events of the game. For example, how Joker adjusts to normal school life again while still having his Persona powers. Another could be a story where the Phantom Thieves discover a new threat that is related to the remnants of the Metaverse they thought they had defeated. Maybe a new group is trying to use the Metaverse for evil in a different way.
Well, in 'Persona 4 New Game Plus Fanfiction', there might be a plot development where the characters remember more from their previous play - through. This could lead to them making different decisions earlier on. Maybe they could anticipate certain events and try to change the outcome. Also, the Velvet Room might have some new features or interactions for the characters, which would add a whole new layer to the story.
In 'Persona 5 New Game Plus Fanfiction', a great plot development could be the exploration of the consequences of the choices made in the first playthrough. The characters may have to deal with the aftermath of their actions, whether good or bad. For instance, if they made a choice that seemed right at the time but had unforeseen negative impacts on the city or a particular character. This could lead to a whole new set of quests and interactions as they try to rectify the situation. Also, new characters might be introduced who are related to these consequences, adding more depth to the story.
One idea could be the characters from Persona 4 and Persona 5 swapping their worlds. So the Phantom Thieves end up in Inaba and have to deal with the Midnight Channel mystery. And the Investigation Team finds themselves in Tokyo and gets involved in the Metaverse. It would be really cool to see how they interact with the different environments and characters.
Another plot twist could be that one of the main Lion King 2 characters, like Kovu, is actually a reincarnation of a powerful Naruto character. This would change his role completely. He might have memories of his past life as a ninja and use those skills and knowledge to deal with the problems in the Pride Lands. It would also create a really interesting dynamic between him and the other lions, who don't understand his strange new abilities at first.
A possible plot twist could be that the dragons in Game of Thrones are actually the result of some ancient ninja jutsu from Naruto's world. Maybe a long - ago ninja experimented with a powerful jutsu that created these creatures. Another twist could be that Jon Snow has some hidden ninja blood in him, which gives him unexpected powers and abilities that no one in Westeros has ever seen before.
Well, perhaps a plot twist where the White Walkers are not the ultimate villains. Maybe they are being controlled by a more powerful and hidden force within Westeros. This would turn the whole 'fight against the White Walkers' narrative on its head. Also, a character like Tyrion Lannister could discover he has some sort of magical ability that has been dormant all his life, which would add a whole new layer to his character and his role in the story.
One interesting plot twist could be that Aegon has a secret alliance with a powerful magical being that no one in Westeros suspects. This being could help him in unexpected ways during his conquest, like using magic to disable the defenses of a stronghold just before Aegon's forces arrive.