One common theme is the idea of justice. Tsuna as a phantom thief often has his own sense of right and wrong, and he might steal from the corrupt. Another theme is secrecy, as he has to keep his identity hidden from most people.
Perhaps in this fanfiction, Danny as a kid would have a different perspective on the ghost world. He might be more curious and less jaded. His appearance as a kid could also change how the ghosts interact with him. Some ghosts might underestimate him, which could be an advantage for Danny. He could use this to his benefit when dealing with them, while also trying to figure out how to turn back to his normal self.
One great 'Danny Phantom new kid' fanfiction is 'The New Arrival'. It has an interesting plot where a new kid arrives in Amity Park with mysterious powers that interact in a unique way with Danny's. Another is 'New Kid on the Ghostly Block' which focuses on how the new kid disrupts the existing dynamic between Danny and his ghost - fighting friends. There's also 'A New Kid's Secret' which is full of suspense as the new kid seems to be hiding something big from everyone.
One common theme is Danny's adventures at school while trying to hide his ghost - fighting identity. It adds an element of secrecy and humor as he has to deal with normal school stuff like tests and bullies while also being a superhero in the ghost world.
Well, in St Denis in RDR2, the story of the kid thief might involve a young character who resorts to stealing. Maybe it's out of desperation, like being poor and having no other way to get food or necessities. He might target the rich folks passing through the busy streets of St Denis. The city being a bustling place with a mix of different people provides both opportunities and risks for a young thief.
One popular phantom thief tsuna fanfiction is 'The Adventures of Phantom Thief Tsuna'. It has an exciting plot where Tsuna uses his unique skills to steal precious items while evading the authorities. The character development in it is quite engaging.
You can start by looking on fanfiction.net. It has a large collection of Danny Phantom fanfictions, and you can easily search for ones related to the 'new kid' theme. Another good place is Archive of Our Own (AO3). It has a well - organized tagging system that will help you find the specific fanfictions you're interested in.
One main event could be his first big theft. He might target a wealthy merchant and steal a valuable piece of jewelry. This could put him on the radar of the local law enforcement. Another event could be when he meets someone who tries to help him, like an old man who sees potential in the kid and offers him an honest job. But the kid has to decide whether to take it or continue his life of crime.
๐I recommend the following novels to you. I hope you will like them:
1. [Ask the Thief]: It was also a thieving theme. After the protagonist was framed by someone empty-handed, he had to find out the truth.
2. [The Stealing Rune Wheel: The protagonist steals the sky with one hand and steals the earth with the other. He is an ordinary student on a daily basis and a famous thief in the underground world at night.]
I hope you like this fairy's recommendation. Muah ~๐