Well, they could team up to fight a common enemy. Maybe a powerful villain that neither Young Justice nor Billy Batson could handle alone. Billy could transform into Shazam and use his super strength, flight, and lightning powers in combination with the skills and powers of the Young Justice members like Robin's detective skills or Superboy's strength.
Billy Batson's memories in fanfic can add depth to his character. For example, his memories of facing difficulties before getting his powers can make readers understand his growth better. Maybe he had memories of being bullied at school or feeling lonely at home. These memories, when explored in fanfic, can create a more relatable and three - dimensional character.
Their relationship might start off a bit rocky. Batman is used to working alone and Billy is a free - spirited kid. But over time, Batman's strict discipline could help Billy focus his powers better. Billy, on the other hand, could show Batman that there's more to life than just fighting crime in the shadows. They'd gradually develop a deep bond of trust and respect for each other.
I'm not sure if there is a specific, well - known 'Billy Batson is Batman's son' fanfiction, but in the world of fanfiction, anything is possible. Some fanfictions might be part of a larger crossover universe where different superhero properties are mashed up. This particular concept could lead to some really interesting storylines, like how Billy would deal with Batman's strict code, or how Batman would handle having a super - powered son who also has a very different personality compared to his usual sidekicks.
One great Billy Batson fanfic could be 'The Adventures of Billy Batson Beyond'. It explores new powers that Billy might gain. Another is 'Billy Batson: The Lost Years' which delves into his past before becoming Shazam. There's also 'Billy Batson and the New Allies' where he teams up with other heroes.
The theme of redemption can also be found in some billy batson fanfiction. Sometimes there are characters who have made mistakes in the past and Billy helps them find a path to redemption. Additionally, the exploration of the magical world that gives Billy his powers is a common theme. Writers often expand on the magic, its rules, and its history in their fanfictions.
I think Billy Batson and Robin would make an interesting pair. Robin is all about strategy and detective work, while Billy has that child - like wonder and raw power as Shazam. They could learn from each other. Robin could teach Billy how to better analyze a situation before jumping into action, and Billy could show Robin that sometimes it's okay to rely on pure power and instinct.
Another place could be FanFiction.net. There are many fans who post their creative works there. However, the quality and content can vary widely. You might have to dig a bit through different categories related to the DC universe to find the specific fanfics about these two characters.