A plot twist could be that the family that adopts Billy has a secret connection to the wizard who gave him his powers. Maybe they are descendants of the wizard's helpers, and this connection is slowly revealed as Billy grows up in the family.
It could also be that Billy is adopted by a family in a parallel universe. This family has different versions of the superheroes he knows. Billy has to adapt to this new world and figure out how his powers work differently here, while also dealing with the fact that he's in a strange new family situation.
One great fanfic could be where Billy gets adopted by a kind-hearted single mother. In this story, she discovers his powers gradually and helps him keep his identity a secret while also teaching him about family values. It could be a heartwarming tale of a lost boy finding a true home.
One idea could be that Billy Batson, as Shazam, has to team up with Constantine to fight a demon that is causing chaos in the city. The demon is using magic that is affecting the ley lines, and only by combining Shazam's strength and Constantine's magical knowledge can they stop it.
One idea could be that as Billy turns into a female, she has to deal with different social expectations in Fawcett City. For example, she might find that people treat her differently when she's out as Shazam in her new form.
One idea could be Billy Batson facing a new villain that the Justice League has trouble dealing with on their own. Billy's unique powers as Shazam could be the key to victory. For example, the villain might have the ability to nullify the powers of the Justice League members one by one, but Billy's magic, being different in nature, remains unaffected.
Well, a really interesting plot might be Billy Batson losing his ability to transform into Captain Marvel. He then has to find a way to regain his powers, perhaps by going on a quest that involves traveling to ancient magical places. Along the way, he could learn more about the origin of his powers and the history of the wizard who gave them to him. He might also encounter other young heroes from the Young Justice team who are initially skeptical of his ability to be useful without his powers but then come to see his true worth as Billy, not just as Captain Marvel.
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.
Another storyline might involve Batman and Billy Batson teaming up to take on a common enemy that neither could defeat alone. Maybe a powerful villain who has the ability to manipulate magic and technology at the same time. Their combined skills, Batman's detective work and Billy's superhuman strength, would make for an exciting adventure.
Well, it could be a story where Billy Batson, with his powers as Shazam, looks up to Batman. Maybe he tries to learn from Batman's detective skills. He could see Batman as a role model in the world of crime - fighting, despite having very different powers. Billy might even try to team up with Batman in some undercover mission where his ability to transform into an adult superhero would come in handy.
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.
One interesting plot twist could be that Naruto gets the Rinnegan not through his own power, but as a result of a sacrifice by an unexpected character, like a long - lost Uzumaki relative. This relative could have been secretly protecting Naruto all along and in a moment of great danger, transfers their Rinnegan - like power to him.